Calculators, generators and converters
Everything runs right in your browser: no sign-up, no data sent to a server and no “leave your phone number” forms. Enter the numbers and the result appears immediately.
Sections
Wallpaper, tiles and paint: estimate material from room dimensions, with a cutting allowance and without subtracting windows and doors.
3 tools MathPercentages, shares and changes — the everyday arithmetic behind discounts, markups and comparing numbers.
1 tool ConvertersLength, area, mass, volume and temperature, converted between metric and imperial units without memorising factors.
1 tool GeneratorsTools that create data rather than calculate it: passwords and random values, generated in the browser.
1 tool FinanceLoans and interest: monthly payment, overpayment and the total cost of money over time, without banking jargon.
1 tool RandomnessRandom numbers, coin tosses, dice, list draws and lucky ticket checks — no sign-up required.
6 tools IdentifiersGenerate UUID v4 and v7, ULID and NanoID, then validate and decode existing identifiers — all in the browser.
5 tools HealthQuick estimates such as body mass index and WHO categories. A reference point, not a diagnosis.
1 toolAll tools
Open the catalogRolls from the room perimeter, allowing for pattern repeat and trimming waste.
Renovation Tile calculatorTiles and boxes by area, with an allowance for cuts and grout lines.
Renovation Paint calculatorLitres and cans from wall area, coverage per m² and number of coats.
Math Percentage calculatorThree modes: percent of a number, share and percentage change.
Converters Unit converterFive kinds of quantity and dozens of units, temperature included.
Generators Password generatorA random password with character-set options and an entropy estimate.
Health BMI calculatorBody mass index and its WHO category, with the formula.
Finance Mortgage calculatorMonthly payment, interest paid and the total cost of the loan.
Identifiers UUID generatorUUID v4, v7 and v1 in batches of up to 1,000, with formats and encodings.
Identifiers UUID validatorChecks the format, version and variant, and explains any error.
Identifiers UUID decoderShows the version, variant, fields and creation time of v1, v6 and v7.
Identifiers ULID generator26-character sortable IDs: a timestamp plus 80 random bits.
Identifiers NanoID generatorShort URL-safe IDs with a configurable length and alphabet.
Randomness Random number generatorRandom whole numbers in batches, with no repeats, sorting and stats.
Randomness Coin flipHeads or tails: one flip or a series, with the results counted.
Randomness Dice rollerDice from d4 to d20, with the total, breakdown and range, up to 100 at once.
Randomness Random pickerA winner from your list, with or without repeats.
Randomness Lucky ticket checkerChecks a number against the classic equal-halves rule.
Randomness Fortune wheelYour own options, weights, odds and win history on one wheel.
Why this site exists
Everyday calculation rarely needs heavy machinery, but it almost always needs accuracy. One extra roll of wallpaper means another trip to the shop; one missing pack of tiles means a floor opened up a month later. These tools use the formulas installers actually use.
Everything runs on the client side: you type numbers, JavaScript computes the result and never sends it anywhere. That is why the site works offline after the first load, needs no account and keeps no history of your calculations.
Each tool has its own page with the formula explained, answers to common questions and links to related tools. That is better for you and for search: a page answers one specific question instead of trying to be everything at once.