Conversion
Angle
Angle converts a measurement from one unit to another using exact conversion factors.
What this does
Angle converts a measurement from one unit to another using exact conversion factors.
Angle changes a measurement from one unit to another: miles to kilometers, pounds to kilograms, Fahrenheit to Celsius, gallons to liters. Every conversion in a unit family works the same way: each unit has a fixed factor relating it to one base unit, so converting is a matter of multiplying through the base and out the other side.
The formula, explained plainly
Most units convert by pure multiplication. Since one inch is defined as exactly 2.54 centimeters, converting 10 inches means 10 x 2.54 = 25.4 cm. The metric system is built for this: kilo means a thousand, centi a hundredth, milli a thousandth, so metric-to-metric moves are just decimal shifts.
Temperature is the famous exception because its scales start at different zeros. Converting Celsius to Fahrenheit needs both a scale factor and an offset: F = C x 9/5 + 32. The offset is why you cannot convert temperature differences with the same formula you use for absolute temperatures: a 10-degree Celsius rise is an 18-degree Fahrenheit rise, with no 32 involved.
Same name does not always mean same unit. The US fluid ounce (29.57 ml) and the imperial fluid ounce (28.41 ml) differ; the US gallon (3.785 L) and imperial gallon (4.546 L) differ more. Cooking adds its own chaos: a US tablespoon is 14.79 ml while the metric tablespoon is 15 ml, and a 'cup' changes size between the US, the metric world, and Japan.
Weight versus volume is the other great confusion. A fluid ounce measures volume; a weight ounce measures mass, and they meet only for water-like liquids. An ounce of feathers and a fluid ounce of feathers are different questions, which is why Angle keeps the volume and weight families strictly separate.
How to use it
- Enter value.
- Choose from unit.
- Choose to unit.
- Type or paste .
- Read the instant result and the breakdown below it.
- Adjust any input to compare scenarios.
Worked example
With value = 180, from unit = Degrees, to unit = Radians, the result is 3.141593 rad 180 deg = is 3.141593 rad.. The default conversion is a common one you can check against any reference table.
Common mistakes
- Applying a temperature conversion formula meant for absolute temperatures to temperature differences, or vice versa.
- Mixing unit systems mid-calculation, like length in feet with width in meters, without converting first.
- Using the length factor for area or volume (1 m = 3.28 ft, but 1 sq m = 10.76 sq ft and 1 cu m = 35.31 cu ft).
- Assuming all tablespoons and cups are equal: US, metric, and UK cooking measures differ by enough to matter in baking.
- Confusing the troy ounce (31.10 g, precious metals) with the avoirdupois ounce (28.35 g, everything else).
- Rounding the conversion factor before multiplying, which injects error that grows with the size of the value.
- Treating stone, pounds, and kilograms loosely in health contexts where a few percent changes the advice.
- Mixing US and imperial units with the same name: US vs imperial fluid ounces, gallons, and pints are all different sizes.
Limitations
- Some units have multiple historical definitions (the calorie has several); the tool states which one it uses.
- Clothing, shoe, and ring sizes are lookup conventions, not mathematical conversions, and vary by brand and country.
- Factors are standard definitions; your ruler, scale, or thermometer has its own measurement error on top.
- Traditional units vary by country and trade: US customary is the default here unless a unit is labeled imperial or metric.
- Cooking volume-to-weight conversion depends on the ingredient's density: a cup of flour and a cup of honey weigh very different amounts.
Expected accuracy
Most factors are exact by international definition (1 inch = 2.54 cm exactly, per the 1959 international yard and pound agreement), so conversion introduces no error beyond floating-point rounding at about 15 significant digits. Values are shown rounded for readability with full precision underneath.
Privacy
Everything you type stays on your device. The calculation runs in your browser with JavaScript; no input is sent to a server, stored in an account, or shared with anyone.
Sources and standards
- SI base and derived units per the Bureau International des Poids et Mesures (BIPM); US customary definitions per NIST; the 1959 international yard and pound agreement for inch/pound exact values; imperial units per UK Weights and Measures standards.
Bottom line
Angle converts through exact defined factors, so the math is never the weak link: the unit identification is. Check US vs imperial on any unit with a shared name, keep fluid ounces away from weight ounces, and give temperature its offset. When the source of a measurement is ambiguous, convert with the stated definition and note your assumption.
Key insight
Convert through the base unit and keep the factor direction straight: multiply when going to a smaller unit, divide when going larger. When in doubt, sanity-check with a known pair like 1 inch = 2.54 cm.
Frequently asked questions
How do I convert liters to gallons?
Divide liters by 3.785 for US gallons or by 4.546 for imperial gallons. So 20 liters is about 5.28 US gallons. Angle labels which gallon each tool uses so there is no ambiguity.
Can I convert between shoe sizes this way?
Only approximately. Shoe and clothing sizes are manufacturer lookup tables, not mathematical units: a US 9 is not a fixed number of centimeters across brands. Treat size conversions as starting points and check the brand's own chart.
How does unit conversion actually work?
Each unit has a fixed factor to a common base unit. Angle multiplies your value into the base unit, then divides out to the target unit. For most units it is pure multiplication; temperature additionally shifts by an offset because the scales start at different zeros.
What is the difference between a US gallon and an imperial gallon?
A US gallon is 3.785 liters; an imperial gallon is 4.546 liters, about 20% larger. The imperial pint (568 ml) is likewise bigger than the US pint (473 ml). Always check which gallon a recipe, manual, or fuel-economy figure means.
Why is temperature conversion different?
Because Celsius, Fahrenheit, and Kelvin put zero in different places. The formulas F = C x 9/5 + 32 and C = (F - 32) x 5/9 handle both the scaling and the offset. For temperature differences the offset cancels: a 10 C change is an 18 F change.
How many feet are in a meter?
Exactly 3.28084 feet per meter by international definition (1 inch = 2.54 cm exactly). For area multiply by the square (10.7639 sq ft per sq m); for volume by the cube (35.3147 cu ft per cu m).
What is the difference between fluid ounces and ounces?
A fluid ounce measures volume (29.57 ml in the US); an ounce measures weight (28.35 g). They coincide only for water-like liquids where 1 ml weighs about 1 g. For flour, oil, or honey you must convert through the ingredient's density.
Are conversion factors exact?
Most modern ones are, by definition: the inch, pound, and yard were fixed to exact metric values in 1959. Older or traditional units (the calorie, the horsepower) have multiple definitions, and Angle states which one each tool uses.
Why do cooking measurements confuse people?
Because volume and weight share names, and because cups and spoons differ by country. A US cup is 236.6 ml, a metric cup 250 ml. For baking, weighing ingredients in grams sidesteps the entire problem.
What is a troy ounce?
31.10 grams, used for precious metals, versus the everyday avoirdupois ounce of 28.35 grams. Twelve troy ounces make a troy pound, which is lighter than the 16-ounce avoirdupois pound. Gold prices always mean troy ounces.
How do I convert Celsius to Fahrenheit in my head?
Double the Celsius, subtract 10% of that, and add 32. For 20 C: double to 40, minus 4 is 36, plus 32 is 68 F. For Fahrenheit to Celsius, reverse it: subtract 32, halve, add 10%.
What is the difference between a nautical mile and a regular mile?
A nautical mile is 1,852 meters exactly, defined as one minute of latitude; a statute mile is 1,609.34 meters. Aviation and shipping use nautical miles (and knots, nautical miles per hour) because they tie directly to chart coordinates.
How big is an acre?
43,560 square feet, or about 4,047 square meters: roughly 75% of an American football field without the end zones. A square mile contains exactly 640 acres.