What is the difference between metric and imperial systems?

The metric system (SI) uses base-10 units like meters, grams, and liters. The imperial system uses feet, pounds, and gallons. Most countries use metric. The United States, Liberia, and Myanmar are the only countries that have not officially adopted the metric system for everyday use.

How do I convert Fahrenheit to Celsius?

Subtract 32 from the Fahrenheit temperature, then multiply by 5/9. The formula is: °C = (°F - 32) × 5/9. For example, 72°F = (72 - 32) × 5/9 = 22.2°C. For a quick mental estimate, subtract 30 and divide by 2.

How many milliliters are in a cup?

One US cup equals 236.59 milliliters (approximately 237 mL). One metric cup equals exactly 250 mL. One UK/Imperial cup equals 284.13 mL. Recipe conversions should specify which cup measurement is being used, as the difference can affect results in baking.

What is a quick way to convert kilometers to miles?

Multiply kilometers by 0.621 for miles, or use the Fibonacci approximation: consecutive Fibonacci numbers approximate km-to-mile conversions (5 km ≈ 3 miles, 8 km ≈ 5 miles, 13 km ≈ 8 miles). For everyday estimation, divide km by 1.6.

How to Convert Measurements: The Complete Guide to Unit Conversions

Whether you are converting a recipe from metric to imperial, calculating construction materials in different units, or translating international science data, measurement conversion is an essential daily skill. This guide covers conversion formulas, quick reference charts, and practical shortcuts for the most common unit conversions across length, weight, temperature, volume, area, and speed.

February 23, 2026 13 min read Utility

Understanding Measurement Systems

Two primary measurement systems dominate global usage: the metric system (International System of Units, SI) used by the vast majority of the world, and the imperial system used primarily in the United States.

Measurement	Metric Unit	Imperial Unit	Conversion Factor
Length	Meter (m)	Foot (ft)	1 m = 3.281 ft
Weight	Kilogram (kg)	Pound (lb)	1 kg = 2.205 lb
Volume	Liter (L)	Gallon (gal)	1 L = 0.264 gal
Temperature	Celsius (°C)	Fahrenheit (°F)	°F = °C × 9/5 + 32
Area	Square meter (m²)	Square foot (ft²)	1 m² = 10.764 ft²
Speed	km/h	mph	1 km/h = 0.621 mph

Use our temperature converter, speed converter, and number converter for instant conversions.

Length and Distance Conversions

Length conversions are among the most common, especially for international shipping, travel, and construction projects.

Quick Reference Chart

From	To	Multiply By	Example
Inches	Centimeters	2.54	12 in = 30.48 cm
Centimeters	Inches	0.3937	100 cm = 39.37 in
Feet	Meters	0.3048	6 ft = 1.83 m
Meters	Feet	3.2808	10 m = 32.81 ft
Miles	Kilometers	1.6093	5 mi = 8.05 km
Kilometers	Miles	0.6214	10 km = 6.21 mi
Yards	Meters	0.9144	100 yd = 91.44 m

Mental Math Shortcuts: For quick feet-to-meters, multiply by 3 and add 10% (10 ft × 3 = 30, + 10% = 33 → actual is 32.8). For miles-to-kilometers, multiply by 8 and divide by 5 (5 miles × 8 ÷ 5 = 8 km → actual is 8.05).

Weight and Mass Conversions

Weight conversions are critical for cooking, shipping, health metrics, and international commerce.

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 = 226.8 g
Grams	Ounces	0.03527	500 g = 17.64 oz
Tons (US)	Metric Tons	0.9072	1 ton = 0.91 t
Stones	Kilograms	6.3503	10 st = 63.5 kg

For health-related weight conversions, use our BMI calculator which automatically handles unit conversion between pounds/feet and kilograms/meters.

Temperature Conversions

Temperature conversion is one of the most commonly needed calculations, whether checking weather forecasts, cooking, or working with scientific data.

Core Temperature Formulas

Celsius to Fahrenheit: °F = (°C × 9/5) + 32
Fahrenheit to Celsius: °C = (°F - 32) × 5/9
Celsius to Kelvin: K = °C + 273.15
Fahrenheit to Kelvin: K = (°F - 32) × 5/9 + 273.15

Key Temperature Reference Points

Description	°C	°F	K
Absolute zero	-273.15	-459.67	0
Water freezes	0	32	273.15
Room temperature	20-22	68-72	293-295
Body temperature	37	98.6	310.15
Water boils	100	212	373.15

Use the temperature converter for instant, accurate temperature conversions.

Volume and Cooking Conversions

Volume conversions are especially important in cooking, where recipes from different countries use different measurement systems.

Measurement	Equivalent
1 US cup	236.59 mL / 8 fl oz
1 tablespoon	14.79 mL / 3 teaspoons
1 US gallon	3.785 L / 128 fl oz
1 liter	0.264 US gallons / 33.81 fl oz
1 US quart	0.946 L / 32 fl oz
1 UK pint	568.26 mL (20% larger than US pint)

Cooking Caution: US and UK fluid measurements differ. A US pint is 473 mL while a UK pint is 568 mL. A US cup is 237 mL while an Australian cup is 250 mL. When following international recipes, verify which measurement standard is being used.

Conversion Tools

Free Online Converters:

Temperature Converter — Celsius, Fahrenheit, Kelvin
Speed Converter — mph, km/h, knots, m/s
Currency Converter — International currencies
Timestamp Converter — Date/time formats
Time Zone Converter — Global time zones
Number Base Converter — Hex, decimal, binary

Frequently Asked Questions

Metric uses base-10 units (meters, grams, liters). Imperial uses feet, pounds, gallons. Most countries use metric. The US, Liberia, and Myanmar have not fully adopted metric for daily use.

°C = (°F - 32) × 5/9. Quick estimate: subtract 30 and divide by 2. Example: 72°F = (72 - 32) × 5/9 = 22.2°C.

US cup = 237 mL, metric cup = 250 mL, UK cup = 284 mL. Specify which standard when converting recipes.

Multiply km by 0.621. Or use the Fibonacci trick: 5 km ≈ 3 miles, 8 km ≈ 5 miles, 13 km ≈ 8 miles. For estimation, divide km by 1.6.

Converters

Temperature Converter
Speed Converter
Currency Converter
Time Zone Converter
Number Converter

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