Unit Converter

How the conversions work

Length and weight conversions work by converting your value to a common base unit, then to the target unit:

Temperature uses dedicated formulas instead, since the scales don't share a common zero point:

Reference: common conversion factors

Step-by-step: converting a recipe or travel distance

1. Pick the right category — length for distances, weight for ingredients or body weight, temperature for oven settings or climate.
2. Select the unit you're converting from and the unit you need.
3. Enter the value — the result updates instantly as you type.
4. For oven temperatures specifically, double-check whether a recipe means a fan (convection) or conventional oven, since some recipes adjust the target temperature depending on which — this calculator converts the number itself, not oven-specific adjustments.

Worked example: converting a recipe from a US site

A US recipe calls for 2 cups of flour and an oven temperature of 350°F. Using the weight conversion, 2 cups of all-purpose flour is roughly 240-250 grams (cup-to-gram conversions vary slightly by ingredient density, so flour, sugar, and liquids each convert a little differently). Converting the oven temperature: (350 − 32) × 5/9 = 176.7°C, which most people would round to 175°C or 180°C depending on their oven's increments. This kind of two-step conversion — one for ingredient quantities, one for temperature — comes up constantly when following recipes written for a different unit system.

A note on precision and rounding

Most everyday conversions (cooking, travel distances, casual weight checks) don't need more than 2-3 decimal places of precision, which is what this tool displays. For scientific or engineering work where rounding error compounds across many calculations, use the full unrounded conversion factor directly rather than a rounded intermediate result — for example, 1 mile is exactly 1,609.344 meters, and rounding that to 1,609.34 introduces a tiny error that's irrelevant for a road trip but could matter in a precise engineering calculation repeated many times.

Why the world uses two different systems

Most countries use the metric system, built on units of 10 that make conversion between scales (millimeters to meters to kilometers) a matter of moving a decimal point. The United States remains a notable exception, still using the imperial system (feet, pounds, Fahrenheit) for everyday life, even though metric is standard in US science, medicine, and much of manufacturing. This split is exactly why unit conversion tools stay useful long-term: a recipe, product spec, or travel distance from a US source often needs converting for a reader anywhere else in the world, and vice versa.

Everyday situations where unit mix-ups cause real problems

• Cooking — a recipe's cup and ounce measurements don't translate directly to grams without knowing the ingredient, since a cup of flour and a cup of sugar weigh different amounts.
• Travel — misreading a speed limit or distance sign in the "wrong" unit system is a common and avoidable travel mistake.
• Shopping internationally — clothing and shoe sizing, as well as product weights, often use different regional units that don't map onto each other with a single simple formula.
• Health tracking — body weight, recorded in kilograms in one country's health record and pounds in another, needs an accurate conversion to compare over time.

Frequently asked questions