Convert between common length, weight, volume, and data units, including metric and imperial, with instant results as you type.
Your value is first converted to a common base unit (meters for length, kilograms for weight), then converted from that base into your target unit.
Unit conversion translates a measurement from one system or scale to another using a fixed conversion factor between the two units. Some conversions are simple multiplication (like length or weight), while others — like temperature — require an offset in addition to a scaling factor.
For example, converting miles to kilometers: 1 mile = 1.60934 km, so 10 miles = 10 × 1.60934 = 16.0934 km.
| From | To | Multiply by |
|---|---|---|
| Miles | Kilometers | 1.60934 |
| Pounds | Kilograms | 0.453592 |
| Gallons (US) | Liters | 3.78541 |
| Inches | Centimeters | 2.54 |
| Square feet | Square meters | 0.092903 |
The metric system is based on powers of 10 (meters, grams, liters, with prefixes like kilo- and milli-), making conversions within the system simple multiplication or division by 10. The imperial/US customary system uses less consistent ratios (12 inches per foot, 3 feet per yard, 5,280 feet per mile), which is why cross-system conversion factors look less "round."
Example 1 — Length: Converting a 5K race (5 kilometers) to miles: 5 ÷ 1.60934 = 3.107 miles.
Example 2 — Weight: A 75 kg person's weight in pounds: 75 ÷ 0.453592 = 165.3 lbs.
Example 3 — Temperature: A 20°C day in Fahrenheit: (20 × 9/5) + 32 = 36 + 32 = 68°F.
Example 4 — Compound unit: A speed of 100 km/h in mph: 100 ÷ 1.60934 = 62.14 mph.
| From | To | Multiply by |
|---|---|---|
| Feet | Meters | 0.3048 |
| Ounces | Grams | 28.3495 |
| Liters | US gallons | 0.264172 |
| Square meters | Square feet | 10.7639 |
| Kilometers | Miles | 0.621371 |
| Question | Answer |
|---|---|
| 32 oz to cups | 4 cups |
| 6 tbsp to cups | 0.375 cups |
| 1/8 cup to tbsp | 2 tbsp |
| 750 ml to oz | ≈ 25.36 fl oz |
| 72 inches to feet | 6 ft |
| 80 cm to inches | ≈ 31.50 in |
| 18 cm to inches | ≈ 7.09 in |
| 8 mm to inches | ≈ 0.315 in |
| 80 kg to lbs | ≈ 176.37 lb |
| 1 oz to grams | ≈ 28.35 g |
| 160 kg to lbs | ≈ 352.74 lb |
| 12 cm to inches | ≈ 4.72 in |
Select the matching category above (Length, Weight, or Volume) and pick the same "from" and "to" units to reproduce any of these — or enter your own value for an exact result.
Keiser machines (like the M3i bike or Air300 series) use pneumatic resistance rather than a fixed weight stack, so the resistance level shown on the console isn't measured in pounds and doesn't convert to pounds using a single fixed multiplier the way length or weight units do. Pneumatic resistance changes with pedal or movement speed, not just the resistance setting, so the same level can feel like a different effective load depending on how fast you're moving. For an accurate pounds-equivalent at a given speed, check the specific conversion chart published by Keiser for your machine model rather than a generic conversion factor.
| Question | Answer |
|---|---|
| How many ounces in a pound? | 16 oz |
| How many pounds in an ounce? | 0.0625 lb (1/16 lb) |
| How many ounces in a liter? | ≈ 33.81 fl oz |
| How many grams in an ounce? | ≈ 28.35 g |
| How many grams in a kilogram? | 1,000 g |
| How many pounds in a kilogram? | ≈ 2.205 lb |
| How many cups in a quart? | 4 cups |
| How many quarts in a gallon? | 4 quarts |
| How many cups in a gallon? | 16 cups |
| How many feet in a mile? | 5,280 ft |
| How many km in a mile? | ≈ 1.609 km |
These are the most commonly searched unit pairs — for anything not listed here, select the matching category above and enter your exact value.
| US (Men's) | UK | EU |
|---|---|---|
| 8 | 7.5 | 41 |
| 9 | 8.5 | 42.5 |
| 10 | 9.5 | 44 |
| 11 | 10.5 | 45 |
| 12 | 11.5 | 46 |
Shoe sizing isn't a fixed mathematical conversion factor like length or weight — it's based on brand- and region-specific last (mold) measurements, so this table gives common approximate equivalents rather than an exact formula. Always check the specific brand's size chart when precision matters.
| Inches | Centimeters |
|---|---|
| 1 in | 2.54 cm |
| 2 in | 5.08 cm |
| 3 in | 7.62 cm |
| 4 in | 10.16 cm |
| 5 in | 12.70 cm |
| 6 in | 15.24 cm |
| 8 in | 20.32 cm |
| 10 in | 25.40 cm |
| 12 in | 30.48 cm |
| Kilograms | Pounds |
|---|---|
| 1 kg | 2.20 lb |
| 5 kg | 11.02 lb |
| 10 kg | 22.05 lb |
| 20 kg | 44.09 lb |
| 50 kg | 110.23 lb |
| 75 kg | 165.35 lb |
| 100 kg | 220.46 lb |
| Celsius | Fahrenheit |
|---|---|
| 0°C | 32°F |
| 10°C | 50°F |
| 20°C | 68°F |
| 25°C | 77°F |
| 30°C | 86°F |
| 37°C | 98.6°F |
| 100°C | 212°F |
Why isn't temperature conversion just a multiplication? Because the zero points of Celsius, Fahrenheit, and Kelvin scales don't align, an additive offset is needed alongside the scaling factor.
Are US and UK gallons the same? No — a US gallon (3.785 L) is smaller than a UK imperial gallon (4.546 L), a common source of conversion errors.
Why do some conversions have so many decimal places? Many cross-system conversion factors (like miles to km) aren't naturally round numbers, since the two systems were defined independently using different base units.
Why did the US never fully switch to the metric system? Historical, economic, and infrastructure reasons made a full switch costly, so the US customary system remains dominant in everyday use even though metric is standard in science and much of world trade.
What's the difference between mass and weight in conversions? Mass (kilograms, pounds as a mass unit) measures the amount of matter and stays constant everywhere; weight is a force that depends on gravity, though in everyday conversions pounds and kilograms are commonly treated as interchangeable mass units.
How do I convert between area units like acres and square meters? Multiply by the fixed conversion factor for that pair (1 acre = 4,046.86 m²); area conversions between systems use the square of the linear conversion factor when derived from base length units.
Why do cooking recipes sometimes use volume and sometimes weight? Different culinary traditions favor different measurement styles — US recipes often use volume (cups, tablespoons) while many other countries favor weight (grams), which don't convert with a single fixed factor for ingredients of different densities.
How many cups is 32 oz? 32 fluid ounces equals 4 cups, since 1 US cup is defined as 8 fluid ounces.
How many tablespoons are in 1/8 cup, or how many cups is 6 tablespoons? 1/8 cup equals 2 tablespoons, and 6 tablespoons equals 0.375 cups, since 1 US cup is 16 tablespoons.
How many ounces is 750 ml? About 25.36 US fluid ounces (750 ÷ 29.5735).
How many feet is 72 inches, and how many inches is 80 cm? 72 inches is exactly 6 feet; 80 cm is about 31.5 inches.
How many pounds is 80 kg? About 176.37 pounds (80 ÷ 0.453592).
How many pounds is 160 kg? About 352.74 pounds (160 ÷ 0.453592).
How many inches is 12 cm? About 4.72 inches (12 ÷ 2.54).
How many cups are in a pint, quart, or gallon? 1 US pint = 2 cups, 1 US quart = 4 cups, and 1 US gallon = 16 cups — each unit doubles the one before it.
How many MB are in a GB? 1 GB = 1,024 MB using the binary convention common in operating systems, or 1,000 MB using the decimal convention some storage manufacturers use. Select the Data category above to convert exactly.
How do I convert mcg to mg? Divide by 1,000 — 1 milligram equals 1,000 micrograms. The Weight category above now includes mcg directly.
What is normal body temperature in Celsius and Fahrenheit? Normal human body temperature is about 37°C, which equals 98.6°F, using the formula °F = (°C × 9/5) + 32.
Converting 5 miles to kilometers: 5 miles × 1.60934 km/mile ≈ 8.05 km — using a base-unit approach, this could also be found by first converting miles to meters, then meters to kilometers, arriving at the same result.
Base unit: A standard reference unit (like meters or kilograms) used as an intermediate step when converting between other units.
Conversion factor: The fixed multiplier used to convert a value from one unit to another.