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Add or subtract a number of working days (Monday to Friday) from a start date, optionally skipping England and Wales bank holidays.

Work out an exact age from a date of birth, as of today or an optional 'as of' date.

Work out UK alcohol units in a drink from its ABV (percentage) and volume (millilitres), using units = ABV x ml / 1000.

Sort the lines of a block of text into alphabetical order.

Convert an angle from one unit to another.

Convert an area from one unit to another.

Aspect ratio helper.

Work out the mean, median, mode, sum, count, minimum and maximum of a list of numbers.

Encode text to RFC 4648 Base32 or decode Base32 back to text.

Encode text to Base64, or decode a Base64 string back to text.

Split a restaurant bill between people.

Generate one or more UK 90-ball bingo cards.

Check whether a Bitcoin address is valid by verifying its checksum and structure.

Work out body mass index (BMI) from height and weight, with the NHS weight category.

Estimate body fat percentage using the US Navy tape method from a few measurements.

Encode or decode text with a Caesar shift cipher.

Work out the compound annual growth rate (CAGR) that takes a starting value to an ending value over a number of years.

Convert food energy between kilocalories (kcal) and kilojoules (kJ) using the exact factor 1 kcal = 4.

Convert text to a different letter case.

Convert a cat's age in years to an approximate human age, using the standard 15, 24, then 4 a year chart.

Convert a temperature between Celsius and Fahrenheit.

Count the characters in a block of text, including a count with spaces removed, the word count, how many SMS messages it would take to send, and the Twitter/X characters remaining out of 280.

Identify what encoding or classical cipher a piece of text probably is (Base64, Base32, hex, binary, octal or decimal ASCII, URL encoding, HTML entities, Morse, Caesar or ROT-N, Atbash, reversed text) or recognise it as a UUID, IPv4 address, Unix timestamp, JWT or hash digest.

Convert a height between centimetres and feet/inches.

Convert print CMYK values (each 0 to 100) to on-screen RGB and hex, or convert RGB (each 0 to 255) the other way to CMYK.

Flip a fair coin one or more times.

Find the named CSS colour that exactly or most closely matches a hex code, using straight-line distance in RGB space across the 148 named CSS colours.

Generate a five-swatch colour palette from a base hex colour using a chosen scheme: analogous, complementary, triadic or mixed.

Given a six-digit hex colour code (with or without a leading #), return its hex, RGB and HSL values.

From a base hex colour, generate five progressively lighter tints (mixed towards white) and five progressively darker shades (mixed towards black), each in five equal steps of one sixth.

List every way to choose r items from a list, ignoring order (combinations).

Project savings growth from a starting deposit plus a regular monthly contribution, compounded monthly with contributions added at the end of each month.

Work out the WCAG contrast ratio between a foreground (text) colour and a background colour, both as hex codes, and report whether it passes AA and AAA for normal and large text.

Translate a standard five-field cron expression (minute, hour, day-of-month, month, day-of-week) into plain English.

Work out profit or loss on a crypto trade from buy price, quantity and an optional per-side fee percentage.

Build a ready-to-use CSS gradient from two colours.

Minify CSS by removing comments and needless whitespace, while preserving quoted strings and the spaces inside calc() expressions.

Convert CSV text into a JSON array, following standard CSV quoting rules for embedded commas, quotes and line breaks.

Convert US cups of a common baking ingredient to grams (approximate).

Convert an amount of money from one currency to another using Hopi's live mid-market exchange rates (updated hourly, 150+ currencies).

Convert a digital storage size between units.

Add or subtract a number of days, weeks, months or years from a date.

Find which day of the week a given date falls on.

Convert between a contractor day rate and an annual salary equivalent using a chosen number of billable working days per year (default 220).

Count the number of days between two dates, with the total also shown in weeks and in weekdays (Monday to Friday).

Count the number of sleeps until the next Christmas Day (25 December).

Work out the average cost basis across a series of pound-cost-averaged buys.

Roll one or more dice with a given number of sides.

Compare two texts line by line using a longest common subsequence diff, and report which lines were added and which were removed.

Work out a discount and sale price.

Convert a dog's age in years to an approximate human age, using the standard veterinary chart.

Estimate how long a download takes.

Estimate a pregnancy due date from the first day of the last menstrual period (LMP) and cycle length.

Generate fake but safe UK test records.

Build a correctly percent-encoded mailto link from to, cc, bcc, subject and body fields, plus a ready to paste HTML anchor snippet.

Remove emoji from a block of text, leaving the words and normal punctuation intact.

Work out the running cost of an electrical appliance from its power in watts, hours used per day and your electricity unit price in pence per kWh.

Convert between a .

Validate an Ethereum address's EIP-55 capitalisation checksum and return the correctly checksummed form.

Convert an amount given in wei, gwei or ETH into all three units, using exact 18-decimal integer maths (no floating point error).

Generate random EuroMillions lines.

Work out how many bottles of red, white and Champagne to buy for an event, from the number of guests and glasses per guest.

Crack open a virtual fortune cookie and receive a random cheerful fortune.

Add, subtract, multiply or divide two fractions, giving the simplified result, a mixed number where relevant, and the decimal value.

Convert between fractions and decimals.

Estimate the fuel cost of a journey from the distance in miles, the car's fuel economy in miles per gallon (UK gallon) and the pump price in pence per litre.

Compute the SHA-256, SHA-1 or SHA-512 hash of a piece of text and return the hex digest.

Identify the most likely algorithms behind a hash string from its length, character set and any prefix.

Estimate maximum heart rate and five training zones (bpm) from age.

Convert a hex colour code (3, 6 or 8 digits, with or without a leading #) to its RGB and HSL values.

Work out UK statutory paid holiday entitlement from the number of days worked per week, using 5.

Convert between an hourly pay rate and an annual salary based on hours worked per week (52 weeks a year).

Work out the hours worked between a start time and an end time, minus an optional unpaid break.

Convert a hex colour code to hue, saturation and lightness (HSL), or convert HSL values to hex and RGB.

Escape the five special HTML characters (& < > " ') into entities so text is safe to place in HTML, or unescape named and numeric HTML entities back into plain characters.

Look up a standard HTTP status code by number and get its name, meaning and class (1xx to 5xx), or search all standard codes by a word in the number, name or description.

Validate an IBAN or generate a test IBAN.

Build a .

Adjust a money amount for UK inflation.

Pretty print, minify or validate JSON.

Convert a JSON array of objects into CSV.

Convert a JSON sample into TypeScript interfaces and types.

Convert data between JSON and YAML in both directions.

Decode a JSON Web Token's header and payload from base64url.

Convert a weight in kilograms to UK stone and pounds.

Check whether a year is a leap year, applying the divisible-by-4, century, and divisible-by-400 rules.

Convert a length from one unit to another.

Convert between litres and pints.

Work out the monthly repayment on a loan from the amount borrowed, the annual interest rate and the term in years, using the standard amortising formula.

Generate lorem ipsum placeholder text.

Generate random lines for a UK lottery game: Lotto (6 numbers from 1 to 59), Thunderball (5 from 1 to 39 plus a Thunderball from 1 to 14) or Set For Life (5 from 1 to 47 plus a Life Ball from 1 to 10).

Ask the Magic 8 Ball a yes or no question and receive one of its twenty classic answers at random.

Work out profit, gross margin and markup from a cost price and a selling price.

Render a small, safe subset of markdown to HTML: headings (# to ###), bold, italic, links (http, https or mailto only), inline code, fenced code blocks, bulleted and numbered lists, and blockquotes.

Calculate a coin's market cap (price times circulating supply) and fully diluted valuation, or work backwards to the price implied by a target market cap.

Build a complete HTML head snippet from page details: title, meta description, canonical link, Open Graph and Twitter card tags.

Convert between miles and kilometres.

Convert between 24-hour (military) time and 12-hour clock time.

Convert a number of minutes into hours and minutes, or convert hours (plus optional extra minutes) into total minutes.

Work out the moon phase for a date, based on the synodic month since a known new moon.

Translate text into international Morse code, or Morse code back into text.

Work out the monthly payment on a repayment mortgage at a constant interest rate, using the standard amortising formula.

See how much time and interest a regular monthly overpayment saves on a repayment mortgage.

Convert fuel economy between UK miles per gallon and litres per 100 km.

Work out UK employee Class 1 National Insurance for the 2026/27 tax year from an annual gross salary.

Spell text out using the NATO phonetic alphabet (Alfa, Bravo, Charlie and so on), or convert a phonetic spelling back into plain text.

Work out the gross salary needed to achieve a desired take-home (net) pay for the 2026/27 tax year in England, Wales and Northern Ireland, using code 1257L income tax bands with personal allowance taper and employee National Insurance.

Convert a whole number from one base to another between binary, octal, decimal and hexadecimal.

Convert a number into written English words.

Convert an oven temperature.

Work out gross overtime pay from a base hourly rate and hours worked at three multipliers: standard (1x), time and a half (1.

Estimate how strong a password is: an entropy estimate in bits, a rough offline crack time (assuming ten billion guesses a second), a 0 to 4 score with a verdict, and warnings about weak patterns such as dictionary words, sequences and repeats.

Work out percentages three ways.

Work out the percentage change from a starting value to an end value, using the starting value as the base.

Decrease a number by a percentage and see the new value and the amount taken off.

Work out the percentage difference between two values using the average-based formula: the absolute gap divided by the average of the two, times 100.

Increase a number by a percentage and see the new value and the amount added.

Work out how large a position to take so that hitting the stop-loss loses only a chosen percentage of the account.

Convert power from one unit to another.

Convert pressure from one unit to another.

Check whether a whole number (2 to 1,000,000,000,000,000) is prime, break it into its prime factors in power form, count its divisors, and list them.

Work out a pro rata salary for part-time hours by scaling a full-time salary by the ratio of your hours to full-time hours.

Turn product rows into a platform-valid product feed: Meta (Facebook and Instagram) RSS 2.

Generate a random colour and return its hex, RGB and HSL values.

Generate random geographic coordinates that are uniform by surface area across the globe (points are not bunched at the poles).

Generate random letters from the alphabet, optionally limited to vowels or consonants.

Generate one or more random whole numbers within a range (inclusive), optionally with no repeats.

Shuffle a list of names and deal them evenly into a set number of teams.

Generate random everyday English nouns, with no repeats.

Work with ratios.

Estimate how long a block of text takes to read.

Work out UK statutory redundancy pay for redundancies on or after 6 April 2026, using the gov.

Remove duplicate lines from a block of text, keeping the first occurrence of each line in its original order.

Tidy up spacing in text: collapse runs of spaces, tabs and non-breaking spaces down to a single space and trim each line.

Remove line breaks from text.

Reverse text in one of three ways.

Convert red, green and blue values (each a whole number from 0 to 255) to an uppercase hex colour code.

Convert a ring size between UK, US and millimetre scales.

Build a robots.

Convert between numbers and Roman numerals, both directions, for whole numbers from 1 to 3999.

Round a number to a chosen number of decimal places or significant figures, with halves always rounded up (away from zero).

Work out running pace, finish time or distance, in kilometres or miles.

Convert satoshis to BTC, mBTC and bits, or convert BTC to satoshis, mBTC and bits.

Plan a savings goal, compounded monthly.

Build valid JSON-LD structured data using schema.

Evaluate a maths expression following the standard order of operations (BODMAS).

Draw Secret Santa gift pairings from a list of names.

Convert a UK shoe size to approximate EU and US sizes.

Suggest sleep times using 90-minute cycles plus 15 minutes to fall asleep.

Spin a slot machine reel of names or options and pick one at random.

Turn any title or text into a clean URL slug: lowercase, accents stripped, and every run of spaces, punctuation and symbols collapsed to a single hyphen, with hyphens trimmed from the ends.

Convert text into decorative Unicode styles.

List special characters and symbols grouped by category: arrows, stars and hearts, maths, currency, punctuation, legal marks and accents.

Convert a speed from one unit to another.

Spin the bottle and pick one player at random from those in the circle.

Format a SQL query: uppercase the keywords, put each clause on its own line and indent conditions, while leaving quoted strings, identifiers, numbers and comments untouched.

Turn a quoted staking rate into a final balance and rewards earned.

Work out Stamp Duty Land Tax (SDLT) on a property purchase in England and Northern Ireland.

Work out the sample and population standard deviation, sample and population variance, mean and count from a list of numbers.

Find the western zodiac star sign for a date of birth.

Work out UK student loan repayments from an annual salary using 2026/27 thresholds.

Work out UK take-home pay from an annual gross salary for the 2026/27 tax year in England, Wales and Northern Ireland, using code 1257L income tax bands (20/40/45%) with personal allowance taper above £100,000, plus employee National Insurance.

Draw a tarot spread from all 78 Rider-Waite-Smith cards, dealt without replacement using cryptographic randomness.

Estimate daily calories (TDEE) and BMR using the Mifflin-St Jeor equation.

Generate Luhn-valid TEST card numbers for QA and development, or validate a card number.

Repeat a piece of text a chosen number of times, joined by an optional separator, with optional line numbering.

Split a long block of text into smaller blocks.

Add or subtract two durations, each given as hours and minutes.

Convert a wall-clock date and time from one time zone to another, using the server's IANA time zone data (so daylight saving is handled).

Work out a tip on a bill and optionally split the total between people.

Solve a right-angle triangle from any two given values, at least one of which must be a side.

Add up UCAS tariff points from A-level grades using the current tariff: A* 56, A 48, B 40, C 32, D 24, E 16.

Inspect text as Unicode.

Compare the unit price of two or more items to find the best value.

Convert between Unix epoch timestamps and readable dates.

Flip text upside down using Unicode look-alike characters and reverse its order, so it reads as if rotated 180 degrees.

Percent-encode or decode text for URLs.

Parse a URL into its parts: protocol, host, port, path, fragment, origin and every decoded query parameter.

Parse a user agent string into its parts: browser and version, rendering engine, operating system and version, device type (mobile, tablet or desktop) and whether it looks like a bot or crawler.

Invent memorable usernames by pairing a random adjective with a random noun, optionally with a two-digit number on the end.

Add UTM campaign parameters (utm_source, utm_medium, utm_campaign, utm_term, utm_content) to a URL without breaking existing query parameters.

Generate 1 to 100 random version 4 UUIDs using a cryptographically secure random source.

Add UK VAT to a net amount, or remove VAT from a gross (VAT-inclusive) amount.

Encode or decode text with the classic Vigenere cipher using a keyword.

Convert a volume from one unit to another.

Estimate a rough daily fluid target from body weight, using 30 to 35 ml per kg, plus an activity add (sedentary 0, light 250, moderate 500, active 750, very_active 1000 ml) and 500 ml more for hot conditions.

Find the ISO 8601 week number for a date.

Convert a weight from one unit to another.

Spin a wheel of names or options and pick one at random.

Analyse a block of text and return the word count, character count (with and without spaces), sentence count, paragraph count and an estimated reading time at 225 words per minute.

Count how often each word appears in a block of text, sorted from most to least frequent.

Count the working days (Monday to Friday) between two dates, inclusive of both ends, optionally excluding England and Wales bank holidays.

Draw original, family-friendly would-you-rather pairs, open icebreaker questions or rapid-fire this-or-that pairs, optionally filtered by category.

Get a random yes or no decision, with an optional maybe.

Hide a secret message inside ordinary text using invisible zero-width Unicode characters, reveal a message hidden that way, or clean zero-width characters out of text.