Unit Conversion Cheat Sheet: The Most Common Conversions You Need
Whether you are following a recipe from another country, shopping for furniture online, or interpreting a weather forecast in Celsius, unit conversions come up constantly. This cheat sheet gathers the most common conversions in one place with exact factors and easy-to-remember approximations.
Length Conversions
The United States uses inches, feet, yards, and miles while most of the world uses the metric system. Here are the exact conversion factors you need.
| From | To | Multiply By | Example |
|---|---|---|---|
| Inches | Centimeters | 2.54 | 12 in = 30.48 cm |
| Centimeters | Inches | 0.3937 | 30 cm = 11.81 in |
| Feet | Meters | 0.3048 | 6 ft = 1.8288 m |
| Meters | Feet | 3.2808 | 2 m = 6.56 ft |
| Yards | Meters | 0.9144 | 100 yd = 91.44 m |
| Miles | Kilometers | 1.6093 | 5 mi = 8.05 km |
| Kilometers | Miles | 0.6214 | 10 km = 6.21 mi |
Quick Tips for Length
- 1 inch is about 2.5 cm. For a rough estimate, multiply inches by 2.5.
- 1 meter is roughly 3 feet 3 inches — just a bit longer than a yard.
- A kilometer is about 0.6 miles. To convert km to miles quickly, multiply by 6 and drop the last digit (10 km × 6 = 60 → 6.0 miles).
- 5 miles is almost exactly 8 km. The Fibonacci trick: consecutive Fibonacci numbers approximate mile-to-km conversions (5 mi ≈ 8 km, 8 mi ≈ 13 km).
Weight Conversions
Weight is one of the most frequent conversion needs, especially for cooking, shipping, and fitness tracking.
| From | To | Multiply By | Example |
|---|---|---|---|
| Pounds | Kilograms | 0.4536 | 150 lb = 68.04 kg |
| Kilograms | Pounds | 2.2046 | 70 kg = 154.32 lb |
| Ounces | Grams | 28.3495 | 8 oz = 226.80 g |
| Grams | Ounces | 0.0353 | 500 g = 17.64 oz |
| Pounds | Ounces | 16 | 3 lb = 48 oz |
Quick Tips for Weight
- 1 kg is about 2.2 pounds. To quickly estimate, double the kilograms and add 10%. (70 kg → 140 + 14 = 154 lb.)
- 1 ounce is about 28 grams. A standard letter weighs roughly 1 oz / 28 g.
- A pound is about 454 grams — just under half a kilogram.
Volume Conversions
Volume conversions are essential in the kitchen and come up frequently when comparing product sizes across countries.
| From | To | Multiply By | Example |
|---|---|---|---|
| Cups (US) | Milliliters | 236.588 | 2 cups = 473 mL |
| Tablespoons | Milliliters | 14.787 | 3 tbsp = 44.36 mL |
| Teaspoons | Milliliters | 4.929 | 2 tsp = 9.86 mL |
| Fluid ounces | Milliliters | 29.574 | 8 fl oz = 236.59 mL |
| Gallons (US) | Liters | 3.7854 | 1 gal = 3.79 L |
| Liters | Gallons (US) | 0.2642 | 2 L = 0.53 gal |
| Quarts | Liters | 0.9464 | 1 qt = 0.95 L |
Quick Tips for Volume
- 1 liter is just a hair more than 1 quart — they are nearly interchangeable for rough estimates.
- 1 US cup is about 237 mL, which is close to 240 mL (a common metric "cup" size in some countries).
- A gallon is roughly 3.8 liters. A 2-liter soda bottle is about half a gallon.
Cooking Measurement Conversions
These conversions within the US customary system come up every time you scale a recipe up or down.
| Measurement | Equivalent |
|---|---|
| 1 tablespoon | 3 teaspoons |
| 1 cup | 16 tablespoons |
| 1 cup | 8 fluid ounces |
| 1 pint | 2 cups |
| 1 quart | 4 cups / 2 pints |
| 1 gallon | 4 quarts / 16 cups |
| 1 stick of butter | 8 tablespoons / ½ cup / 4 oz |
When halving a recipe, the trickiest conversion is half of ¾ cup. The answer is 6 tablespoons (since ¾ cup = 12 tablespoons).
Temperature Conversions
Temperature is the one conversion where you cannot just multiply by a single number — you also have to add or subtract an offset.
Formulas
- Fahrenheit to Celsius: °C = (°F − 32) × 5/9
- Celsius to Fahrenheit: °F = (°C × 9/5) + 32
Common Temperature Benchmarks
| Fahrenheit | Celsius | What It Means |
|---|---|---|
| 32°F | 0°C | Water freezes |
| 50°F | 10°C | Cool day, light jacket |
| 68°F | 20°C | Room temperature |
| 72°F | 22°C | Comfortable indoors |
| 86°F | 30°C | Hot summer day |
| 98.6°F | 37°C | Normal body temperature |
| 212°F | 100°C | Water boils |
| 350°F | 177°C | Common oven baking temp |
| 400°F | 204°C | Higher oven baking temp |
| 450°F | 232°C | Pizza / high-heat roasting |
Quick Mental Math for Temperature
For a rough Fahrenheit-to-Celsius estimate: subtract 30, then divide by 2. Example: 72°F → (72 − 30) / 2 = 21°C. (The exact answer is 22.2°C — close enough for deciding what to wear.)
For Celsius-to-Fahrenheit: double it and add 30. Example: 25°C → (25 × 2) + 30 = 80°F. (Exact: 77°F.)
Quick Conversion Tips and Tricks
- Use anchor points. Memorize a few exact conversions (1 inch = 2.54 cm, 1 kg = 2.2 lb, 1 mile = 1.6 km) and estimate from there.
- Round for speed. In daily life, you rarely need four decimal places. Saying "1 kg is about 2.2 pounds" is precise enough for grocery shopping.
- Watch for US vs. Imperial. A US gallon (3.785 L) is smaller than an Imperial gallon (4.546 L). US and Imperial fluid ounces also differ slightly. If you are following a British recipe, this matters.
- Check the direction. The most common conversion mistake is multiplying when you should divide, or vice versa. Ask yourself: "Should my answer be a bigger or smaller number?" Inches to centimeters should get bigger. Pounds to kilograms should get smaller. If your answer goes the wrong direction, flip the operation.