All calculators

Every calculator on the site, grouped by category. More are added as they are built. If a category looks empty, it is because we have not finished the first tool in it yet, not because we have forgotten.

AI

Tools for working with AI APIs and large language models.

• LLM Token Usage Calculator

  Estimate the per-call, daily, monthly and annual cost of an LLM workload across Claude, GPT, Gemini and DeepSeek. Side-by-side comparison, baked-in pricing dated for transparency, browser-only.

• AI Image Generation Cost Calculator

  Estimate the per-image, monthly and annual cost of generating AI images. Side-by-side comparison across DALL-E 3, Midjourney, Stable Diffusion XL, Imagen 3 and Flux Pro, with pricing dated for transparency.

• RAG Pipeline Cost Calculator

  Estimate the monthly cost of running a Retrieval-Augmented Generation pipeline. Embedding, vector database, and LLM query costs broken out, with a month-by-month projection and an LLM swap comparison.

• AI vs Human Writer Cost Calculator

  Compare the monthly cost of producing written content via an LLM against a human writer. Per-word or per-hour human rates, side-by-side model table, honest about editorial trade-offs.

• AI Fine-Tuning Cost Calculator

  Estimate the cost of fine-tuning an LLM. Training cost across GPT-4o, GPT-4o-mini, Llama-3 on Together, and Mistral-7B, with the per-1000-call hosted inference cost for the tuned model.

• AI Hallucination Risk Calculator

  Score the relative risk that an LLM output will hallucinate, given the model class, task, grounding and verification you have in place. Heuristic, browser-only, with the maths shown.

• Embedding Cost Calculator

  Estimate the cost of generating embeddings for a corpus across OpenAI, Cohere, Voyage or a custom price. One-off, monthly, weekly or daily refresh, with total over the period and per-1000-docs cost.

• Prompt Token Estimator

  Paste a prompt, pick a model family, see roughly how many tokens it will use across GPT-4o, Claude, Gemini, Llama and Mistral. Optional cost at your $/1K rate.

Broadband

Work out the speed, bandwidth, and plan that actually fits your household or office.

• Broadband Bandwidth Calculator

  Estimate the download and upload speeds your household needs based on streaming, video calls, gaming, smart devices, and remote work.

• Cloud Backup Time Estimator

  Work out how long the first cloud backup will take on Backblaze, iDrive or any other provider, with protocol overhead and overnight-only mode.

• Web Hosting Storage & Bandwidth Estimator

  Work out how much storage and monthly bandwidth your website needs based on your traffic, page weight, media files, and downloadable content. See which hosting tier fits.

• File Download Time Calculator

  How long will a download take at your line speed? Bits and bytes converted properly, decimal multipliers, with a 5% protocol overhead included and the working shown.

• VPN Throughput Calculator

  Estimate effective speed through a VPN given your link speed, protocol (WireGuard, OpenVPN, IPsec), cipher, CPU class and server distance. Identifies whether encryption, link bandwidth or RTT is the bottleneck.

• Latency Impact Calculator

  See how ping, jitter and packet loss affect cloud gaming, FPS, video calls, browsing or SSH. Get a verdict per use case and an effective TCP throughput cap.

• Streaming Quality Calculator

  Tells you what streaming quality your broadband can actually sustain across Netflix, Disney+, Prime Video and YouTube, with concurrent streams and headroom factored in.

• ISP Speed Reality Check

  Compare what your ISP advertises with the realistic speed you actually get. Factors in connection type, distance from cabinet, line quality, router placement, wifi standard and peak hour contention.

Business

Return on investment, tax obligations, marketing performance and web performance.

• ROI Calculator

  Work out return on investment as a percentage, net profit, and multiple of money. Add a time period to see the annualised return (CAGR). Works for any investment or spend.

• SEO ROI Calculator

  Enter your monthly SEO cost, current and projected organic sessions, and conversion data to see ROI, monthly profit, and the minimum traffic needed to break even.

• Email Marketing ROI Calculator

  Enter your list size, send frequency, open and click rates, and conversion data to see ROI, cost per conversion, and the minimum list size needed to cover your costs.

• UK VAT Calculator

  Add VAT to a net price or remove it from a gross price. Covers all three UK rates: standard (20%), reduced (5%) and zero (0%). Net, VAT amount and gross shown with full workings.

• Website Performance Budget Calculator

  Set concrete page-weight and Core Web Vitals targets for your site type and audience. Add your current load time and revenue figures to see what a slow site is costing you in lost conversions.

• Profit Margin Calculator

  Calculate gross and net profit margin from revenue and costs, or find the selling price needed to hit a target margin. Shows the difference between margin and markup.

• Freelance Day Rate Calculator

  Work out the day rate you need to charge as a freelancer. Accounts for non-billable days, expenses, pension, and gaps between clients.

• Break-Even Calculator

  Find the number of sales needed to cover your costs. Set a profit target to see units required to hit it. Includes a scenario table at different volumes.

• IT Support Build vs Buy Calculator

  Compare the annual cost of hiring in-house IT support against a managed service. Shows the verdict at your headcount, break-even users, and full workings.

• Domain Renewal True Cost Calculator

  See the real multi-year cost of a domain once promo pricing ends and add-ons (privacy, email, DNS, SSL) are included. Optional comparison against a cheaper registrar.

Conversions

Metric-imperial converters for everyday units.

• Unit Converter

  Length, mass, volume, temperature, speed and area. Pick a category, enter a value, see every common unit at once. Metric and imperial side by side.

• Cooking Measurements Converter

  Convert cooking measurements across UK, US and metric conventions. Cups, tablespoons, fluid ounces, grams, ounces, gas mark to Celsius, plus cup-to-grams densities for the ingredients that actually matter.

• Time Zone Converter

  Convert a date and time between IANA time zones. Pick a source, add as many target zones as you need, see day-of-week, local time and UTC offset for each. DST handled by your OS, browser-only.

• Roman Numeral Converter

  Convert numbers to Roman numerals and back, in either direction. Range 1 to 3,999. Lowercase normalised, malformed forms like IIII or VV flagged with the canonical form.

• Fuel Economy Converter

  Live four-way conversion across MPG (UK), MPG (US), L/100km and km/L. Edit any one field, the other three update on the spot. Useful for imported cars and European spec sheets.

• Number Base Converter

  Convert between binary, octal, decimal and hexadecimal with live two-way binding. Arbitrary base 2 to 36 panel. BigInt internals so 64-bit values round-trip without precision loss.

Cybersecurity

Browser-only password and security tools. Nothing you type gets sent anywhere.

• Password Strength Calculator

  Test how strong a password really is. Entropy, breach-list check and crack-time estimates at three threat models, all in your browser.

• Password Generator

  Cryptographically secure passwords and passphrases generated in your browser. Uses Web Crypto. Nothing leaves the device. Disconnect your network and it still works.

• Data Breach Risk Score

  Self-assess your breach exposure across passwords, 2FA, software hygiene and phishing awareness. Get a risk score and a prioritised fix list, all in your browser.

• Data Breach Cost Estimator

  Estimate the financial impact of a data breach using IBM/Ponemon 2024 benchmarks. Per-record cost, GDPR and CCPA fine estimates, and a low/high range to plan against.

• Hash Generator

  Generate SHA-256, SHA-384, SHA-512 and SHA-1 hashes from text or files. Uses Web Crypto in your browser. Drag a 100MB file in, the hash never leaves the device.

• Diceware Passphrase Generator

  Generate a memorable passphrase by drawing words from the EFF short wordlist (1,296 words) using crypto.getRandomValues. Pick word count, separator and capitalisation, see honest entropy figures.

• SSL Certificate Expiry Calculator

  Paste an expiry date or a certificate's openssl text dump and see days remaining, an urgency band, and the date to put the renewal reminder on. Browser-only date arithmetic, no network call.

• 2FA / TOTP Window Calculator

  Reason about your TOTP authentication window. Period, digits, drift and clock skew in; effective acceptance window, per-attempt brute-force odds, attempts-per-second to a 50% hit, and a recommended drift setting out.

Finance

Sensible estimates for personal money decisions.

• US Mortgage Calculator

  Work out your monthly US mortgage payment with principal, interest, property tax, home insurance, HOA and PMI broken out separately. Total interest and total cost over the life of the loan.

• UK Mortgage Calculator

  Work out a UK monthly mortgage payment during the fixed-rate period and after it reverts to the lender's Standard Variable Rate, plus stamp duty and all the cash you need on completion day.

• Loan Calculator

  Work out the monthly payment, total interest and total cost of any fixed-rate personal, auto or student loan. See how much you save by paying extra each month. Currency is a toggle.

• Compound Interest Calculator

  See how a starting balance and regular contributions grow with compound interest. Optional inflation adjustment, year-by-year breakdown, currency toggle.

• UK Salary Tax Calculator

  Enter your gross salary to see income tax, National Insurance and student loan deductions broken down, plus take-home by year, month and week. England, Wales and Northern Ireland rates.

• UK Stamp Duty Calculator

  Calculate Stamp Duty Land Tax for a residential purchase in England or Northern Ireland. Covers standard purchases, first-time buyer relief and the additional property surcharge. Full band breakdown.

• Debt Payoff Calculator

  Work out how long it takes to pay off a credit card, loan, or overdraft at a fixed monthly payment. Add an extra monthly payment to see exactly how much time and interest you save.

• Tip Calculator

  Work out the tip, split the bill, and optionally round each person up to a whole number so nobody has to fish out coins. Covers USD, GBP, EUR, CAD and AUD.

• Savings Goal Calculator

  Work out the monthly number you need to hit a savings target by a specific date. Factors in your starting balance and the interest your account pays.

Fun

Calculators that don't pretend to be useful.

• Age in Months Calculator

  Enter a date of birth and find out how many months old you are. As popularised by parents of small children everywhere, who communicate their offspring's age exclusively in this way.

• Date Difference Calculator

  Pick two dates. Get the gap in years, months, days, weeks, hours and weekdays. Useful for deadlines, anniversaries, and any other "how long?" question that comes up on a Monday morning.

• Decision Wheel

  Type a list of options and spin a coloured wheel to pick one. Optional remove-winner mode for tournament-style elimination. Browser-only and cryptographically unbiased.

• Dice and Coin Roller

  Roll any combination of tabletop dice or flip up to 1000 coins. Standard notation: 2d6, 1d20+5, 4d6kh3. Browser-only and cryptographically unbiased, with the working shown so the result is auditable.

• Magic 8-Ball Generator

  Ask any yes/no question. The classic 20-answer oracle, with 10 affirmative, 5 non-committal and 5 negative answers, weighted exactly like the original toy.

• Random Name Picker

  Paste a list of names, choose how many to pick, get a fair random selection. Useful for classroom call-outs, raffle draws, fair team allocations, or settling a decision when nobody can agree. Browser-only and cryptographically unbiased.

Health

Quick health and fitness numbers, with the caveats made plain.

• BMI Calculator

  Work out your body mass index in metric or imperial units, with the WHO category and an honest note on what BMI can and cannot tell you.

• Calorie Calculator

  Calculate your basal metabolic rate and daily calorie target based on your activity level and goal. Includes macro split and a projected timeline for weight change goals.

• Running Pace Calculator

  Work out your running pace, finish time, or distance covered. Enter any two of pace, distance, and time. Metric and imperial, with race time predictions for 5K, 10K, half marathon and marathon.

• UK Marathon Course Difficulty Calculator

  Drop in a GPX file for any UK marathon and a target flat pace. Get a terrain-adjusted finish time, the toughest sections of the course flagged with the time you'll hit them, and a difficulty rating. Strava-style Grade-Adjusted Pace model with late-race fatigue weighting.

• UK Sportive Difficulty Calculator

  Drop in a GPX file for any UK sportive, set your weight and target flat-road speed (or sustained power), get a physics-based finish time, the categorised climbs flagged with arrival times, and your top descent speed. Standard cycling-power equation with rider-type CdA and Crr presets.

• TDEE Calculator

  Work out Total Daily Energy Expenditure and BMR using Mifflin-St Jeor, Harris-Benedict or Katch-McArdle. Includes cut and bulk targets and a starting macro split.

• Macro Split Calculator

  Turn a daily calorie target into grams of protein, carbs and fat. Goal presets or a custom three-slider ratio that always sums to 100. Per-meal breakdown included.

• Pregnancy Due Date Calculator

  Work out your estimated due date from your last period, conception date, or IVF transfer date. Shows current gestational age, trimester, and key milestone dates.

Images

Resize, convert and inspect photos without uploading them anywhere.

• Photo Resizer

  Resize and convert photos in your browser. Pick a width, a height, a format and a quality. Your image never leaves your device.

• WebP to JPG Converter

  Convert WebP images to JPG or PNG in your browser. Drag and drop, bulk conversion, optional resize. Fixes the Chrome WebP problem in Word, Outlook and PowerPoint.

• Image Compressor

  Compress JPG, PNG and WebP photos to a target file size, like 2 MB for an upload form or 500 KB for email. Multiple files at once, browser-only.

• HEIC to JPG Converter

  Convert iPhone HEIC and HEIF photos to JPG, PNG or WebP in your browser. Drop one file or a holiday's worth, get downloads back. Files never leave your device.

• Aspect Ratio Calculator

  Work out the matching width or height that keeps an image or video at the same aspect ratio. Live two-way binding, simplified ratio shown via GCD, preset ratios in one click.

• Image File Size Estimator

  Estimate the file size of a JPEG, PNG, WebP, AVIF or HEIC from its pixel dimensions and quality, before you encode anything. Side-by-side comparison of all five formats.

• Color Depth & Storage Calculator

  Calculate the uncompressed size of an image at any bit depth, the total colours that depth can represent, and how it compares to a typical JPEG or PNG.

• Image DPI / Print Size Calculator

  Convert between pixels, DPI and print size in either direction. Quality verdict tells you whether the print will look sharp or visibly pixelated.

Math

Everyday maths tools for quick, honest answers.

• Percentage Calculator

  Work out a percentage of a number, what percent one number is of another, or the percentage change between two values.

• Discount Calculator

  Sale price calculator covering single discounts, stacked discounts, sales tax or VAT, and Buy X Get Y Free deals. Currency-agnostic, with workings shown.

• Fraction Calculator

  Add, subtract, multiply or divide fractions and mixed numbers. Returns the simplified fraction, the mixed-number form and the decimal, with every step of the working shown.

• Standard Deviation Calculator

  Paste a list of numbers and get count, mean, median, range, variance and standard deviation, sample and population, with the working shown step by step.

• GCD and LCM Calculator

  Find the greatest common divisor (HCF) and lowest common multiple of two or more whole numbers. Shows the Euclidean algorithm, prime factorisations and the combined-prime LCM working.

• Quadratic Equation Solver

  Solve any quadratic ax² + bx + c = 0. Returns the two roots, the discriminant, the vertex, the axis of symmetry and the y-intercept. Handles real and complex roots with full working shown.

• Logarithm Calculator

  Compute log base b of x for any positive base, including base 10, e and 2. Solve for the result, for x, or for the base. Change-of-base working and inverse check shown.

• Combinations & Permutations Calculator

  Work out nCr, nPr, factorials and multinomial coefficients with arbitrary precision. Handles repetition variants and shows the formula and step-by-step working.

Productivity

Browser-based tools for everyday tasks. Nothing uploaded, nothing stored.

• iCal Event Generator

  Create a .ics calendar file for any event. Set the date, time, timezone, location and recurrence, then download and import into Google Calendar, Apple Calendar, Outlook, or any other calendar app.

• Meeting Cost Calculator

  See what a meeting actually costs in money and lost productivity. Per-attendee breakdown, annualised weekly figure, person-hours, plus a live ticker that climbs in real time once you press start.

• Pomodoro Session Planner

  Plan a chunk of focused work into Pomodoro sessions. Work out sessions needed, total focus and break time, finish time today, and how it splits across days when one day is not enough.

• Project Deadline Countdown Calculator

  Count the calendar days, working days and working hours left until a project deadline. Tick the days you actually work, paste in any holidays, see the percentage elapsed and a mini-calendar of the days that count.

• Sprint Capacity Planner

  Plan a sprint by capacity, not gut feel. Per-person availability, holidays, ceremonies and focus factor combine into person-hours, person-days and a story-point forecast with a confidence band.

• Time Card Calculator

  Weekly timesheet calculator. Enter start and end times, plus unpaid breaks, for each day. Returns hours per day, total hours for the week, and total pay if you add an hourly rate. Handles overnight shifts.

Property

Figures for buying, renting, moving, and maintaining a home.

• Rental Yield Calculator

  Gross yield, net yield, monthly cash flow and return on deposit for any rental property. Currency toggle, workings shown.

• UK Rent vs Buy Calculator

  Compare the net cost of buying a UK home against renting over any horizon. Stamp duty, mortgage interest, maintenance, selling costs and the opportunity cost of the deposit all included.

• UK Mortgage Overpayment Calculator

  See how much interest you save and how many years you shave off your UK repayment mortgage by paying extra each month or making a one-off lump sum. Yearly balance comparison and 12-month worked example.

• UK House Move Cost Calculator

  Total cost of moving home in the UK, broken out line by line. Stamp duty (SDLT, LBTT or LTT), conveyancing, mortgage fees, survey, removals, EPC and estate agent, with a best- and worst-case spread.

• UK Section 24 Buy-to-Let Tax Impact Calculator

  Compare your individual landlord tax bill before and after Section 24, with a side-by-side limited company corporation tax comparison and the full step-by-step working. Shows whether Section 24 has pushed you into a higher band.

• UK Leasehold Ground Rent & Service Charge Calculator

  Project annual cost over a chosen period for a UK leasehold flat. Models fixed, doubling and RPI-linked ground rent escalation, service charge inflation, and the post-2022 peppercorn rule.

SEO

Practical SEO tools that run in your browser.

• URL Slug Generator

  Turn any heading into a clean, ASCII-safe, hyphen-separated URL slug. Optional stop-word stripping and length cap.

• Meta Length Checker

  Check SEO title and meta description against Google's display limits in characters and approximate pixel width.

• Keyword Density Calculator

  Paste an article or page and see word counts plus 1-, 2- and 3-gram keyword density tables. Optional stop-word filter, runs in your browser.

• Robots.txt Tester

  Paste a robots.txt and check whether a URL is allowed or blocked for Googlebot, Bingbot or any user-agent. Follows Google's spec, shows the winning rule.

• CTR by SERP Position Estimator

  Estimate clicks from a Google ranking. Pick a position 1 to 20, set monthly volume and SERP features, and see expected click-through rate based on Advanced Web Ranking 2024 data.

• SERP Snippet Preview Tool

  Preview how a page title, meta description and URL render in Google's desktop and mobile search results. Truncation calculated by pixel width, not character count.

Wedding

Planning tools for weddings. Timeline generators, date calculators, and checklists.

• Save the Date Calculator

  Enter your wedding date to get a personalised planning timeline: when to send save-the-dates, book vendors, send formal invitations, set the RSVP deadline, and handle final preparations.

• Wedding Budget Calculator

  Enter your total budget and guest count to get a recommended spend breakdown across venue, catering, photography, music, flowers, attire, stationery, transport, and contingency.

• Wedding Day Timeline Generator

  Enter your ceremony time and reception end time to generate a complete wedding day schedule from bridal preparation through to carriages.

• Wedding Drinks Calculator

  Enter your guest count and event duration to get bottle and quantity estimates for white wine, red wine, prosecco, beer and cider, spirits, and soft drinks.

• Wedding Table Planner Calculator

  Enter your guest count and preferred table size to find out how many tables you need, how many seats will be spare, and how alternative sizes compare.

• Wedding Catering Calculator

  Enter your guest count, meal style, and number of courses to get portion counts and food weight estimates for canapés, wedding breakfast, evening food, and tea and coffee.

• Wedding Anniversary Calculator

  Enter your wedding date to find out which anniversary you are celebrating, the traditional and modern gift themes, and your upcoming milestone anniversaries.

Writing

Tools for writers, editors, and anyone working with words.

• Flesch Reading Ease Score Calculator

  Paste text and see its Flesch Reading Ease score and Flesch-Kincaid Grade Level, with the word, sentence and syllable counts that produced them.

• Read Time Calculator

  Paste any text to see word count, character count, sentence count, and estimated reading time silently and aloud. Useful for blog posts, scripts, speeches, and podcast outlines.

• Word Count Tool

  Live word, character, sentence and paragraph counts, plus fit-checks for tweet, meta description, SMS and SEO title limits.

• Suffolk Lorem Ipsum Generator

  Placeholder text in Suffolk dialect, drawn from Charlie Haylock's work and the East Anglian dialect tradition. Affectionate pastiche, not the real thing.

• English to Suffolk Translator

  Paste any English text and see it transformed into Suffolk dialect, word by word. Shares its vocabulary with the Suffolk Lorem Ipsum generator.

• Headline Power-Word Score

  Score a headline 0 to 100 based on power words, length, sentiment skew, numbers and stop-word ratio. Get suggestions to make it punchier.

Coming soon

Categories with calculators in the pipeline but not yet published.

• Property

  Figures for buying, renting, moving, and maintaining a home.