The exact factors worth keeping handy
Nearly all common US units are defined today in terms of metric ones, so their factors are exact. These are the ones used most.
| Unit | Equals |
|---|---|
| 1 pound (lb) | 0.45359237 kg (453.59237 g); 1 kg ≈ 2.20462 lb |
| 1 ounce (oz, weight) | 28.349523 g, rounded to 28.35 g; 16 oz = 1 lb |
| 1 inch (in) | exactly 2.54 cm |
| 1 foot (ft) | 0.3048 m (12 inches) |
| 1 yard (yd) | 0.9144 m (3 feet) |
| 1 mile (mi) | 1.609344 km (5,280 feet) |
| 1 US gallon | 3.785411784 L |
| 1 imperial (UK) gallon | 4.54609 L |
| 1 US cup | about 236.6 ml (8 fluid ounces) |
| 1 metric cup | 250 ml |
One detail that trips people up: the UK imperial gallon is about 20 percent larger than the US gallon (4.546 L versus 3.785 L). When a source doesn't say which one it means, it is usually the US gallon, which is also what the tool uses unless it says UK.
Weight: pounds, ounces and kilos
To turn pounds into kilos, multiply by 0.45359237; to turn kilos into pounds, multiply by 2.2046226. A worked example: a person who weighs 150 lb weighs 150 × 0.45359237 = 68.04 kg. And 70 kg is 70 × 2.2046226 = 154.32 lb.
| Pounds | Kilos | Kilos | Pounds |
|---|---|---|---|
| 1 lb | 0.454 kg | 1 kg | 2.205 lb |
| 10 lb | 4.54 kg | 5 kg | 11.02 lb |
| 25 lb | 11.34 kg | 20 kg | 44.09 lb |
| 100 lb | 45.36 kg | 50 kg | 110.23 lb |
| 150 lb | 68.04 kg | 70 kg | 154.32 lb |
| 200 lb | 90.72 kg | 100 kg | 220.46 lb |
In the UK, body weight is sometimes given in stones: 1 stone = 14 lb ≈ 6.35 kg. The tool shows that too.
The gym: plates and barbells
US gyms load plates in pounds. The most common plate weighs 45 lb, which is 45 × 0.45359237 = 20.41 kg, not exactly 20 kg. An Olympic barbell is usually either 20 kg or 45 lb (20.4 kg), depending on the gym, so check the markings on the bar.
| Total load | In kilos | How it is built (45 lb bar) |
|---|---|---|
| 95 lb | 43.1 kg | bar + one 25 lb plate per side |
| 135 lb | 61.2 kg | bar + one 45 lb plate per side |
| 185 lb | 83.9 kg | bar + one 45 and one 25 per side |
| 225 lb | 102.1 kg | bar + two 45 lb plates per side |
| 315 lb | 142.9 kg | bar + three 45 lb plates per side |
Check one: 135 lb = 45 for the bar + 2 × 45 for the plates; 135 × 0.45359237 = 61.23 kg.
Cooking: ounces, cups and spoons
In an American recipe, one cup is 236.6 ml, one tablespoon (tbsp) is 14.8 ml and one teaspoon (tsp) is 4.9 ml; 16 tablespoons make a cup. One ounce of weight is 28.35 g.
Careful: cups measure volume and grams measure weight, so turning a cup into grams depends on the ingredient. Approximate values for a US cup: water about 237 g, all-purpose flour about 125 g, granulated sugar about 200 g, butter about 227 g. They vary with how you fill the cup (sifted or packed flour, for example), so treat them as a guide.
| Measure (US) | Milliliters |
|---|---|
| 1/4 cup | 59 ml |
| 1/3 cup | 79 ml |
| 1/2 cup | 118 ml |
| 3/4 cup | 177 ml |
| 1 cup | 237 ml |
| 2 cups | 473 ml |
Weight ounces to grams: 1 oz = 28 g; 4 oz = 113 g; 8 oz = 227 g; 12 oz = 340 g; 16 oz = 454 g. For ingredients, the Unit converter has a Cooking category: choose the "Ingredient" and it converts between cups, spoons and grams using reference values, always approximate. For baking, weighing in grams is more reliable than any cup.
Running: from miles to kilometers
A mile is 1.609 km, so kilometers become miles when multiplied by 0.6214. The best-known race distances work out like this.
| Distance | Kilometers | Miles |
|---|---|---|
| 5K race | 5 km | 3.11 mi |
| 10K race | 10 km | 6.21 mi |
| Half marathon | 21.0975 km | 13.11 mi |
| Marathon | 42.195 km | 26.22 mi |
| 3 miles | 4.83 km | 3 mi |
| 5 miles | 8.05 km | 5 mi |
Pace changes too: 5:00 min per km equals 5 × 1.609344 = 8.05 min per mile, or about 8:03 min/mi. If your watch or app is set to miles and your reference times are in kilometers, convert the pace, not just the distance.
Driving: mph and km/h
One mile per hour is 1.609344 km/h. To estimate, multiply by 1.6; to go from km/h to mph, multiply by 0.62. On the road, these are the values you meet most often.
| mph | km/h | km/h | mph |
|---|---|---|---|
| 25 mph | 40.2 km/h | 50 km/h | 31.1 mph |
| 30 mph | 48.3 km/h | 80 km/h | 49.7 mph |
| 55 mph | 88.5 km/h | 100 km/h | 62.1 mph |
| 60 mph | 96.6 km/h | 120 km/h | 74.6 mph |
| 65 mph | 104.6 km/h | 130 km/h | 80.8 mph |
| 70 mph | 112.7 km/h | 140 km/h | 87.0 mph |
100 km/h is about 62 mph. For speeds, use the Speed category of the Unit converter; Miles to km converts distances.
Fuel: gallons, liters and fuel economy
In the US gas is sold by the gallon: 10 gallons is 37.85 L (10 imperial gallons would be 45.46 L). If a sign says 4.00 per gallon, a liter costs 4.00 ÷ 3.785 = 1.06.
Fuel economy changes even more. Europe and much of the world use liters per 100 km (L/100 km), where lower is better; the US uses miles per gallon (mpg), where higher is better. They convert with one constant: L/100 km × mpg = 235.215 (for the US gallon; with the imperial gallon the constant is 282.48).
| L/100 km | km/L | mpg (US) |
|---|---|---|
| 5 | 20 | 47.0 |
| 6 | 16.7 | 39.2 |
| 8 | 12.5 | 29.4 |
| 10 | 10 | 23.5 |
| 12 | 8.3 | 19.6 |
Example: a 30 mpg car uses 235.215 ÷ 30 = 7.84 L per 100 km. It is an estimate: real consumption depends on how you drive and the road. The Unit converter has a Fuel economy category with US mpg, UK mpg, km/L and L/100 km.
Estimation tricks and typical mistakes
- Kilos to pounds: double it and add 10 percent. 80 kg: 160 + 16 = 176 lb (exact: 176.4).
- Pounds to kilos: take half and subtract 10 percent of that half. 180 lb: 90 − 9 = 81 kg (exact: 81.6).
- Miles to kilometers: multiply by 1.6. 26.2 mi × 1.6 ≈ 41.9 km (exact: 42.2).
- Inches to centimeters: multiply by 2.5. 10 in ≈ 25 cm (exact: 25.4).
- Liters to US gallons: divide by 4 and add 5 percent. 40 L: 10 + 0.5 = 10.5 gal (exact: 10.57).
- A weight ounce and a fluid ounce are not the same thing: 8 fluid ounces of water take up 237 ml and weigh about 237 g, but 8 ounces of weight are 227 g. With very dense or very light foods the gap is even larger.
- US and UK gallons, pints and fluid ounces differ: a US pint is 473 ml and a British pint is 568 ml.
- Short ton versus metric ton: 2,000 lb is 907.2 kg, while a metric ton is 1,000 kg (2,204.6 lb).
- Troy ounce: the ounce used for precious metals is 31.1035 g, not 28.35 g.
How to use the ABC SyG tools
Each conversion has a direct tool: Lbs to kg, Kg to lbs, Miles to km, Ounces to grams and Cups to ml. They all work the same way and calculate in your browser, without uploading what you type.
- Type the amount in the "Value" field.
- See the result highlighted at the top and, below it, the equivalents in other units of the same category.
- Change the number to try other values.
- Tap "Copy result" to take the equivalents with you.
For other quantities, the Unit converter covers length, weight, volume, speed, fuel economy, cooking and more. It rounds to 8 significant digits, and cooking measurements are approximate.
Frequently asked questions
How many kilos is 150 pounds?
150 pounds is 68.04 kg: 150 × 0.45359237. For a mental estimate, half is 75, and subtracting 10 percent gives 67.5.
How many kilometers is 26.2 miles?
26.2 miles is about 42.16 km. The marathon is exactly 42.195 km, which is 26.22 miles.
How many grams are in an ounce?
One weight ounce (avoirdupois) is 28.35 g. Don't confuse it with the troy ounce used for precious metals, which is 31.1 g, or with the fluid ounce, which measures volume.
How many milliliters are in a cup?
The US cup is about 236.6 ml. The metric cooking cup is rounded to 250 ml, and depending on the country or recipe it can be 240 ml.
Is a US gallon the same as a UK gallon?
No. The US gallon is 3.785 L and the imperial gallon is 4.546 L, about 20 percent larger. When converting fuel economy in mpg, you need to know which one the figure uses.