Universal Unit Converter

Common unit conversions

• 1 inch = 2.54 cm · 1 foot = 30.48 cm · 1 yard = 0.9144 m
• 1 mile = 1.609344 km · 1 li (里) = 500 m
• 1 lb = 453.592 g · 1 oz = 28.3495 g · 1 ton = 1,000 kg
• 1 mu (亩) = 666.67 m² · 1 hectare = 15 mu · 1 acre = 4,046.86 m²
• 1 L = 1,000 mL · 1 US gallon = 3.785 L

How to use this converter

Pick a category tab, type a value in either box — the other side updates instantly. Switch either dropdown to change units at any time; the conversion is always live and two-way.

Why accurate unit conversion matters

In a global economy, unit conversion errors can be costly. In 1999, NASA lost the $125 million Mars Climate Orbiter because one team used imperial units and another used metric. In everyday life, conversion mistakes can cause cooking failures, wrong medication doses, shipping delays or construction errors. Always double-check your conversions, especially for safety-critical tasks.

Metric vs imperial systems

The metric system (SI) is used by almost every country in the world. It is decimal-based (units differ by powers of 10), making conversions simple: 1 km = 1,000 m, 1 kg = 1,000 g. The imperial system is used primarily in the United States and a few other places. Its units are not decimal-based: 1 mile = 1,760 yards = 5,280 feet, 1 pound = 16 ounces.

Temperature conversion formulas

Common reference points: Water freezes at 0 °C = 32 °F, boils at 100 °C = 212 °F. Normal body temperature is about 37 °C = 98.6 °F. Absolute zero is 0 K = −273.15 °C = −459.67 °F.

Chinese traditional units

• 斤 (jīn): 1 斤 = 500 g = 0.5 kg. Used for food and produce in markets. 1 kg = 2 斤.
• 里 (lǐ): 1 里 = 500 m = 0.5 km. Used for road distances. 1 km = 2 里.
• 亩 (mǔ): 1 亩 ≈ 666.67 m². Used for land area. 1 hectare = 15 亩, 1 acre ≈ 6.07 亩.
• 两 (liǎng): 1 两 = 50 g = 0.1 斤. Used for precious metals and traditional Chinese medicine.

Practical examples

• Cooking: A recipe calls for 2 cups of flour. 1 US cup = 236.59 mL, so 2 cups = 473.18 mL.
• Body weight: You weigh 70 kg. In pounds: 70 ÷ 0.453592 ≈ 154.32 lb. In 斤: 70 × 2 = 140 斤.
• Fuel economy: 30 miles per gallon (US) = 30 × 1.609344 ÷ 3.78541 ≈ 12.75 km per liter.
• Room size: A 15 m² room. In 亩: 15 ÷ 666.67 ≈ 0.0225 亩. In square feet: 15 × 10.7639 ≈ 161.46 ft².

Tips for accurate conversions

• Round only the final answer. Keep full precision during intermediate steps to avoid compound rounding errors.
• Know your significant figures. If you measure 1.2 m, don't report a conversion to 1.2192 m with 5 decimal places.
• Double-check temperature. Temperature conversion is not a simple multiplication — it requires addition/subtraction of 32 and multiplication by 5/9 or 9/5.
• Watch US vs UK units. US gallons and UK gallons differ (US = 3.785 L, UK = 4.546 L). Same for fluid ounces and tons.