Conversions & Units

Calculate missing width or height from a target aspect ratio, or simplify any pixel dimensions to their lowest-term ratio (16:9, 4:3, 21:9 and more). Instant visual rectangle preview.

Calculate exactly how long a file will take to download. Handles decimal (MB=10⁶) vs binary (MiB=2²⁰) prefixes and bits-vs-bytes — far more accurate than a simple SERP result.

Convert between mpg (US & UK), L/100km, km/L and mi/L instantly. Understand the inverse relationship between mpg and litres-per-100km with a visual comparison bar. Free and instant.

Convert land area between m², km², hectares, acres, sq ft, sq yd, and South-Asian regional units — bigha, kanal, marla, katha, cent. Includes a to-scale plot visualiser.

Convert any number between binary, octal, decimal, hexadecimal and any base from 2 to 36 — with a step-by-step positional breakdown showing digit × base^place.

Calculate screen PPI (pixel density), print size from pixel dimensions, or pixels needed for a target print size. Understand the difference between PPI and DPI.

Convert ring sizes between EU/ISO, US, UK and Japanese systems instantly. Enter inner circumference, diameter, or a known size — get all four systems plus a to-scale circle diagram. Free.

Convert between Arabic numbers and Roman numerals instantly. See the step-by-step additive breakdown (e.g. 1994 → M+CM+XC+IV). Supports 1–3999. Free and instant.

Convert shoe sizes instantly between US (men/women/kids), UK, EU and Japanese sizing. Enter your foot length or a known size to see all systems at once.

Convert between °C, °F, K and °Rankine all at once, with a visual thermometer marking freezing, body temperature, boiling and oven heat. Free and instant.

Convert any unit instantly: metres, feet, kilograms, pounds, litres, gallons, m², acres, km/h, mph and more — all in one free universal converter.

Calculate video file size from bitrate and duration, or find the bitrate needed to hit a target file size. Compare 720p, 1080p and 4K storage requirements instantly.