# Conversions & Units — YouCalc

> Length, weight, temperature, volume, and unit swaps.

## All Conversions & Units calculators

- [Aspect Ratio Calculator](https://youcalc.com/en/conversions-units/aspect-ratio-calculator/): 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.
- [Download Time Calculator](https://youcalc.com/en/conversions-units/download-time-calculator/): 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.
- [Fuel Economy Converter](https://youcalc.com/en/conversions-units/fuel-economy-converter/): 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.
- [Land Area Converter](https://youcalc.com/en/conversions-units/land-area-converter/): 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.
- [Number Base Converter](https://youcalc.com/en/conversions-units/number-base-converter/): 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.
- [PPI & DPI Calculator](https://youcalc.com/en/conversions-units/ppi-dpi-print-size/): 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.
- [Ring Size Converter](https://youcalc.com/en/conversions-units/ring-size-converter/): 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.
- [Roman Numeral Converter](https://youcalc.com/en/conversions-units/roman-numeral-converter/): 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.
- [Shoe Size Converter](https://youcalc.com/en/conversions-units/shoe-size-converter/): 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.
- [Temperature Converter](https://youcalc.com/en/conversions-units/temperature-converter/): 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.
- [Unit Converter](https://youcalc.com/en/conversions-units/unit-converter/): Convert any unit instantly: metres, feet, kilograms, pounds, litres, gallons, m², acres, km/h, mph and more — all in one free universal converter.
- [Video File Size Calculator](https://youcalc.com/en/conversions-units/video-file-size-calculator/): 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.

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