Everyday
Percentages, tips & quick math
Everyday calculators
5 tools for Percentage, Tip split, Fuel cost and more — accurate, instant, and free.
Reckonist’s Everyday calculators turn quick real-life maths into instant answers — percentages and percentage change, splitting a tip or a bill, fuel cost and mileage, unit conversions, and ratios. Each one runs in your browser — simple, free, no sign-up, and your figures never leave your device.
Converters3
Unit Converter
Convert between length, weight, temperature, volume, area and speed units both directions — with the exact SI/NIST conversion factor, a table of nearby values, and a live re-converter. Temperature uses the affine °C/°F/K formula (not a naive multiply), and US and UK volume units (gallon, pint, fluid ounce) are handled distinctly. Computed entirely in your browser.
Roman Numeral Converter
Convert numbers to Roman numerals and back — with the subtractive breakdown (IV = 4, not IIII), a reference chart, and both directions in your browser. Great for date tattoos and anniversaries: 2024 is MMXXIV. Standard notation covers 1–3999; larger values need a vinculum (noted). Decoding validates the numeral and rejects malformed input.
Aspect Ratio Calculator
Resize an image or video keeping its aspect ratio — enter one new dimension and get the other with no distortion — or reduce any width×height to its simplest ratio (1920×1080 → 16:9) via the greatest common divisor. Includes common-ratio presets (16:9, 4:3, 1:1, 9:16, 4:5, 21:9), the decimal ratio, and a fit-vs-crop helper. Computed entirely in your browser.
Codes & alphabets2
Morse Code Translator
Translate text to Morse code and back, and hear it played as audio at an adjustable speed (WPM) and tone — all in your browser. Uses the international ITU-R M.1677 alphabet with PARIS-standard timing (unit = 1200 ÷ WPM ms, dot 1 unit, dash 3 units). Letters are separated by a space and words by a slash; decoding is lenient and unsupported characters are flagged. Includes a full reference chart.
NATO Phonetic Alphabet
Spell any name, code or postcode over the phone with the NATO/ICAO phonetic alphabet — type text and get November-Alfa-Mike-Echo instantly, with a per-letter reference chart. Uses the official ICAO spellings (Alfa, Juliett) and ICAO digit words (3 = Tree, 4 = Fower, 5 = Fife, 9 = Niner), with a toggle for the colloquial Alpha/Juliet forms. Computed entirely in your browser.