🔁 Unit Converter
Convert any measurement — length, weight, temperature, volume, speed, and more.
Our free Unit Converter handles length, weight and mass, temperature, volume, area, speed, pressure, energy, and data storage — all in one tool. Supports both metric (SI) and imperial systems with automatic conversion in both directions.
Most Common Conversions
- Length: 1 inch = 2.54 cm (exact) | 1 mile = 1.60934 km | 1 foot = 30.48 cm
- Weight: 1 kg = 2.20462 lbs | 1 oz = 28.3495 g | 1 stone = 6.35029 kg
- Volume: 1 US gallon = 3.78541 L | 1 fl oz = 29.5735 ml | 1 US cup = 236.588 ml
- Area: 1 acre = 43,560 sq ft = 4,046.86 m² | 1 sq mile = 640 acres = 2.58999 km²
- Speed: 60 mph = 96.56 km/h | 1 knot = 1.852 km/h | 1 m/s = 3.6 km/h
Temperature Conversion
°F to °C: (°F − 32) × 5/9
°C to K: °C + 273.15
Key reference points: 0°C = 32°F (water freezes) | 20°C = 68°F (room temperature) | 37°C = 98.6°F (body temperature) | 100°C = 212°F (water boils)
Quick mental estimate: Double the Celsius and add 30 for a rough Fahrenheit equivalent. 20°C → (20×2)+30 = 70°F (actual 68°F). Close enough for practical purposes.
Metric vs Imperial: Why Both Exist
The United States is one of only three countries worldwide (with Myanmar and Liberia) that has not officially adopted the metric system as the primary measurement standard. This creates constant conversion needs in cooking (US recipes vs European), medicine, science (metric only), engineering, and international commerce.
The metric system is based on powers of 10, making arithmetic straightforward. Imperial units use arbitrary conversion factors (12 inches to a foot, 3 feet to a yard, 1,760 yards to a mile) that require conversion tools rather than mental arithmetic.
Cooking Measurement Conversions
- 1 US cup = 16 tablespoons = 48 teaspoons = 236.6 ml
- 1 tablespoon = 3 teaspoons = 14.79 ml
- 1 UK/Australian tablespoon = 15 ml (UK) or 20 ml (Australia) — different from US!
- 1 UK cup = 284 ml (vs US cup = 237 ml) — significant for old British recipes
For baking, always weigh ingredients in grams rather than measuring by volume. One "cup of flour" can range from 120g to 160g depending on how you scoop it — a 33% variation that causes consistent baking failures.
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Open Unit Converter →Frequently Asked Questions
How do I convert km to miles quickly in my head?
Multiply km by 0.6 for a quick estimate (actual: × 0.6214). So 100 km ≈ 60 miles. Going the other direction, multiply miles by 1.6 for a rough km equivalent. For highway speed limits: 60 mph ≈ 100 km/h, 70 mph ≈ 113 km/h.
What is the difference between mass and weight?
Mass is the amount of matter in an object (measured in kg or lbs). Weight is the gravitational force on that mass (measured in Newtons). On Earth, they're proportional, so we use the terms interchangeably in daily life. On the Moon, your mass is the same but your weight is 1/6th. Our converter handles mass (kg, lbs, g, oz) rather than force.