Unit conversion: length, weight, volume and temperature
Need to switch between metric and imperial? Enter a value, pick the units and get the converted result instantly with the factor shown. The tool covers the everyday swaps you meet in recipes, DIY, travel and school: meters to feet, kilograms to pounds, liters to gallons and Celsius to Fahrenheit, all with the exact factor so you can check the math instead of trusting a rounded number.
En bref
- Every unit in one category shares a base (meters for length, grams for weight, milliliters for volume, seconds for time).
- Formulas: Base = Value x FromFactor | Result = Base / ToFactor | C = (F-32)x5/9 | K = C+273.15
- Example 1: 5 km to miles — Value: 5 km, fromFactor 1000, toFactor 1609.344
How it works
Every unit in one category shares a base (meters for length, grams for weight, milliliters for volume, seconds for time). The calculator turns your value into base units by multiplying by the from-factor, then divides by the to-factor to get the target. Temperature is different because 0 C is 32 F, so you first shift to Celsius and then to the target. Choose length, weight, volume, temperature or time, enter the number and the two units; the result, the base value and the formula are shown together so you can reuse the factor without reopening the tool.
The math
For length, weight, volume and time the conversion is a single ratio: result = value x fromFactor / toFactor. For temperature the offset matters: C = (F - 32) x 5/9 and K = C + 273.15, so you must add or subtract before scaling. The factors are exact definitions (1 inch = 2.54 cm, 1 lb = 453.59237 g, 1 gal US = 3785.411784 ml) so the result is reproducible.
FromFactor and ToFactor are the unit sizes in base units. Temperature first normalizes to Celsius, then converts to the target.
Examples
Example 1: 5 km to miles
- Value: 5 km, fromFactor 1000, toFactor 1609.344
- Base = 5 x 1000 = 5000 m
- Result = 5000 / 1609.344 = 3.10686 mi
Example 2: 70 kg to pounds and 20 C to Fahrenheit
- Weight: 70 kg x 1000 / 453.592 = 154.323 lb
- Temperature: 20 C x 9/5 + 32 = 68 F
When to use it
✦ Travel and Navigation
Convert miles to kilometers for road trips and feet to meters for hiking profiles without mental math.
✦ Cooking and Lab Work
Switch grams to ounces and milliliters to cups so a US recipe works with a European scale.
✦ School Equivalences
Check equivalences for homework (meters, liters, grams) and see the factor, not just the answer.
⚠ Common mistakes
- Forgetting temperature offset: 20 C is 68 F, not 20 x 5/9.
- Mixing mass and weight without factor: 1 kg is 2.20462 lb, not 2.
FAQ (6)
How do I convert units?
Multiply by the from-factor to base units, then divide by the to-factor.
Why does temperature need a different formula?
Because 0 C is 32 F, you must shift the zero before scaling.
Gardez-vous mes nombres pour surfaces ou conversions ?
Jamais. Conversions — kg→lbs, surfaces, fractions — en local, aucun envoi. Vous pouvez convertir 1 500 kg sur un PC partagé et partir tranquille.
Sans internet en cours ?
Oui. Chargez une fois en Wi-Fi, puis fractions, bases ou écart-type passent offline en classe sans réseau. C'est juste des maths en JavaScript.
Quelle précision ?
Définitions standard (1 kg = 2,20462 lbs, BIPM) et tests auto. Pour devoirs ou chantier largement assez ; pour expertise certifiée, vérifiez la norme primaire.
Partager avec un camarade ?
Touchez 'Partager le lien' : il met les saisies dans l'URL, votre camarade voit le même 3/4 → 0,75 → 75% sans ressaisir.
Sources et Références
Comment cette calculatrice est maintenue
Cette calculatrice est écrite et maintenue par Davide Coronese, développeur indépendant et fondateur de CalcTracker.
Méthodologie : chaque formule est vérifiée sur des publications officielles et validée par une suite de tests automatisés avant publication. Les pages santé, fiscalité et finance citent les sources exactes utilisées.
Vous avez trouvé une erreur ? Écrivez-nous — les corrections vérifiées sont publiées sous 24 heures.