Unit Converter

About unit conversion

Conversions use standard factors relative to a base unit (meter, kilogram, m/s). Temperature is converted through formulas because the scales do not share a zero point.

How do I convert between units?

To convert between units, multiply the value by its unit's factor relative to a base unit, then divide by the target unit's factor; temperature instead uses a formula since its scales do not share a zero point. Example: 5 kilometers equals 5 x 1000 / 1609.344 = 3.11 miles.

Steps to convert between units

1. Choose a category (length, weight, temperature, or speed) and pick the unit you are converting from and the unit you are converting to.
2. For length, weight, and speed, multiply the input value by the from-unit's factor to convert it into the base unit (meter, kilogram, or meter per second).
3. Divide that base-unit value by the to-unit's factor to get the result in the target unit.
4. For temperature, convert the input to Celsius first using the scale's formula, then convert from Celsius to the target scale.
5. Round the result to a reasonable number of decimal places for the units involved.

Unit conversion formula

• Factor = the unit's fixed ratio to the category's base unit (for example, 1 mile = 1609.344 meters)
• Base unit = meter for length, kilogram for weight, meter per second for speed

Common unit conversions

How many kilometers is 1 mile?

1 mile is 1.609 km (1 mile = 1,609.344 m, this tool's exact length factor).

How many centimeters is 1 inch?

1 inch is 2.54 cm exactly, the internationally defined length of the inch.

How many pounds is 1 kilogram?

1 kg is about 2.205 lb (1 kg ÷ 0.453592 kg per lb = 2.205 lb).

How many centimeters is 1 foot?

1 foot is 30.48 cm exactly (1 ft = 0.3048 m).

How many miles is 5 km?

5 km is about 3.107 mi (5,000 m ÷ 1,609.344 m per mile = 3.107 mi).

How many grams is 1 ounce?

1 oz is about 28.35 g (1 oz = 0.0283495 kg).

How many meters is 1 yard?

1 yard is 0.914 m (1 yd = 0.9144 m exactly).

How many km/h is 1 mph?

1 mph is about 1.609 km/h, using this tool's speed factors (1 mph = 0.44704 m/s, 1 km/h = 0.277778 m/s).

Example unit conversions

Frequently asked questions

Why does temperature use a different method than length or weight?

Length and weight units all start at zero at the same physical point, so a simple multiplication factor works. Temperature scales have different zero points (0C is 32F, not 0F), so conversion requires an addition or subtraction step, not just multiplication.

How many decimal places are the results shown to?

This tool displays up to 6 significant digits after conversion. For most everyday conversions like cooking measurements or travel distances, rounding to 1 or 2 decimal places is precise enough.

What is the exact conversion factor between miles and kilometers?

One mile equals exactly 1,609.344 meters (1.609344 kilometers), an internationally agreed definition. This tool uses that exact factor rather than a rounded approximation.

Can I convert units that are not listed, like volume or area?

This tool currently covers length, weight, temperature, and speed. For other categories, the same base-unit method applies: find each unit's factor relative to a common base and divide accordingly.

This converter uses standard, internationally defined factors; results are exact but display is rounded, and it does not cover specialized or historical units outside the categories listed.

Sources: NIST - The NIST Reference on Constants, Units, and Uncertainty (SI units)

Privacy and safety

• Runs in your browser — Everything you type is calculated on your own device. Your inputs are never sent to a utilduck server.
• Encrypted connection — Pages are served over HTTPS, so nobody on the network can read what you load.
• Not shared with third parties — Your inputs are not passed to analytics or advertising services.
• Nothing is stored — Results are not saved to any server, and there is no account to create.

Last updated: 2026-08-17