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.
TL;DR
- 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.
Do you save the numbers I type for area, volume or conversions?
Not at all. Every conversion — kg to lbs, area, fraction math — runs locally. No form data is posted anywhere. You can convert 1,500 kg to lbs on a shared computer and walk away knowing nothing was logged.
Will it work without internet in class?
Yes — that's why students like it. Load once on Wi-Fi, then fraction, base-converter or standard deviation work offline in class or in an exam hall without signal. It's just math in JavaScript, no server round-trip.
How accurate are the math results?
We use standard definitions (e.g. 1 kg = 2.20462 lbs, BIPM SI) and double-check edge cases via automated tests. For homework or site measurements it's more than enough, but for certified engineering or lab work, cross-check with the primary standard.
Can I share a calculation with a classmate?
Tap 'Share Link' — it puts the inputs in the URL. Your classmate opens it and sees the same 3/4 → 0.75 → 75% breakdown instantly, without retyping.
Sources & References
How this calculator is maintained
This calculator is written and maintained by Davide Coronese, independent developer and founder of CalcTracker.
Methodology: every formula is checked against official publications and validated by an automated test suite before release. Health, tax and finance pages cite the exact sources they rely on.
Found an error? Contact us — verified corrections ship within 24 hours.