Unit Conversion Cheat Sheet: Length, Weight, Volume, Speed and Data

Guides · Jun 6, 2026 · 2 views

You never need unit conversion until you suddenly do — a recipe in cups, a speed limit in mph, a "500 GB" drive that shows 465. Here are the conversions worth memorizing approximately, with exact tools for when approximately isn't enough.

Length

1 inch = 2.54 cm. 1 foot = 30.48 cm. 1 mile ≈ 1.6 km (so 60 mph ≈ 96 km/h). 1 metre ≈ 3.28 feet. Quick trick: km to miles ≈ multiply by 0.6; miles to km ≈ multiply by 1.6. Exact values: length converter.

Weight

1 kg ≈ 2.2 pounds — so a "150 lb" character in an American novel weighs about 68 kg. 1 ounce ≈ 28 grams (relevant for every imported recipe). 1 tonne = 1,000 kg. Exact: weight converter.

Volume

1 US gallon ≈ 3.79 litres (fuel economy comparisons), 1 US cup ≈ 237 ml (baking — and yes, UK cups differ, which is why grams beat cups). Exact: volume converter.

Temperature

°F to °C: subtract 32, multiply by 5/9. Quick approximation: subtract 30, halve it. So 98°F ≈ 34°C-ish, exactly 36.7°C. The anchors: 0°C = 32°F, body temp 37°C = 98.6°F, oven-hot 180°C = 356°F. Exact: temperature converter.

Speed

1 m/s = 3.6 km/h (physics problems), 100 km/h ≈ 62 mph, 1 knot = 1.852 km/h (flights and ships). Exact: speed converter.

Data storage — the 500 GB mystery

Drive makers count 1 GB = 1,000,000,000 bytes; operating systems count 1 GiB = 1,073,741,824 bytes. That's why a "500 GB" drive shows ~465 GB — nothing is missing, the units differ. Also: internet speed is in megaBITS (Mbps), downloads in megaBYTES (MB/s) — divide by 8. A 100 Mbps connection downloads at 12.5 MB/s. Exact: data storage converter.

For everything else — area, pressure, energy, time — the converters are one click away and free.

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