Metric vs Imperial: Conversion Cheat Sheet for Cooking and Travel
An inch is exactly 2.54 cm, a pound exactly 0.45359237 kg, and °F = °C × 9/5 + 32. The tables below cover oven temperatures, US vs metric cups, travel distances and speeds, and why a 500 GB drive shows as 465 GB.
The conversions worth memorizing
A handful of factors cover most everyday situations. Several of these are exact by definition: an inch is exactly 2.54 cm and a pound exactly 0.45359237 kg.
| Imperial / US | Metric | Rough mental version |
|---|---|---|
| 1 inch | 2.54 cm (exact) | 2.5 cm |
| 1 foot | 30.48 cm (exact) | 30 cm |
| 1 mile | 1.609344 km (exact) | 1.6 km; 5 miles ≈ 8 km |
| 1 pound (lb) | 0.45359237 kg (exact) | Halve it, then subtract 10% |
| 1 ounce (oz, weight) | 28.35 g | 30 g |
| 1 US cup | 236.6 ml | 240 ml |
| 1 US fluid ounce | 29.57 ml | 30 ml |
| 1 US gallon | 3.785 L | 3.8 L |
| 1 UK (imperial) gallon | 4.546 L | 4.5 L |
Temperature
°F = °C × 9/5 + 32, and °C = (°F − 32) × 5/9. A quick estimate from Celsius: double it and add 30. It's close for weather (20 °C → 70 °F, real value 68 °F) but too rough for ovens.
| °C | °F | Reference |
|---|---|---|
| −40 | −40 | The two scales meet |
| 0 | 32 | Water freezes |
| 20 | 68 | Room temperature |
| 37 | 98.6 | Body temperature |
| 100 | 212 | Water boils at sea level |
Oven temperatures
Recipes round oven settings, so a US recipe at 350 °F and a European one at 180 °C mean the same thing.
| Common US setting | Exact °C | Typical metric recipe | Use |
|---|---|---|---|
| 325 °F | 163 °C | 160–170 °C | Slow baking, rich cakes |
| 350 °F | 177 °C | 180 °C | Most cakes and cookies |
| 375 °F | 191 °C | 190 °C | Muffins, pastries |
| 400 °F | 204 °C | 200 °C | Roasting vegetables |
| 425 °F | 218 °C | 220 °C | Bread, crisp roasting |
| 450 °F | 232 °C | 230 °C | Pizza, high-heat roasting |
If a metric recipe says "fan" or "convection", it's usually 20 °C lower than a conventional oven setting.
Cooking: cups aren't the same everywhere
A US cup is 236.6 ml, but nutrition labels in the US round it to 240 ml, and Australia, Canada and many recipe sites use a 250 ml "metric cup". The difference is small for liquids and more noticeable in baking. Pints differ too: a US pint is 473 ml and a UK pint 568 ml, about 20% more.
For dry ingredients, cups measure volume, not weight, so a cup of flour and a cup of sugar weigh very different amounts. Approximate weights for one US cup:
| Ingredient (1 US cup) | Approximate weight |
|---|---|
| All-purpose flour, spooned and leveled | 120–130 g |
| Granulated sugar | 200 g |
| Butter | 227 g (2 US sticks) |
| Water or milk | about 240 g |
Flour varies most, depending on how it's packed. For reliable baking, weigh ingredients when a recipe gives grams.
Travel conversions
| You see | It means |
|---|---|
| Speed limit 100 km/h | 62 mph |
| Speed limit 60 mph | 97 km/h |
| 5 km run | 3.1 miles |
| 10 km run | 6.2 miles |
| Half marathon | 21.1 km / 13.1 miles |
| Marathon | 42.2 km / 26.2 miles |
| Height 180 cm | 5 ft 10.9 in (about 5′11″) |
| Weight 70 kg | 154.3 lb |
| Luggage limit 23 kg | 50.7 lb |
Fuel is sold by the liter in most countries and by the US gallon in the US: 1 US gallon is 3.785 liters.
Digital storage: why a 500 GB drive shows 465 GB
Drive makers use decimal units: 1 GB = 1,000,000,000 bytes. Windows reports sizes in binary units, where 1 "GB" is actually 1,073,741,824 bytes (properly called a gibibyte, GiB). The same 500,000,000,000 bytes therefore appear as about 465.7 GB. No space is missing; the two numbers use different units.
Using the Unit Converter
The Unit Converter covers length, weight, temperature, digital storage, area, volume (including US gallons, quarts and cups) and speed. Choose a category, enter a value, and pick the units to convert between. Keep the full result for measurements you'll build or cut from, and round only at the end.
Frequently asked questions
How do I convert kilograms to pounds quickly?
Multiply by 2.2. For example, 70 kg × 2.2 = 154 lb. The exact factor is 2.20462.
Is a UK pint the same as a US pint?
No. A UK (imperial) pint is 568 ml; a US pint is 473 ml.
How many grams are in a cup?
It depends on the ingredient: about 120–130 g for flour, 200 g for sugar and 240 g for water in a US cup.
Why does my recipe turn out differently after converting?
Cup sizes differ between countries, and dry ingredients vary in how they're packed. Weighing ingredients in grams gives the most consistent results.