TOOLGENIEFree Unit Converter Online
Convert length, weight, temperature, volume, area, speed, time, and data — metric ↔ imperial, instant in your browser
Popular conversions
100 cm = 39.37007874 in
1 cm = 0.39370079 in → 100 × 0.39370079 = 39.37007874 in
Quick table: Centimeter → Inch
| cm | in |
|---|---|
| 1 | 0.39370079 |
| 2 | 0.78740157 |
| 5 | 1.96850394 |
| 10 | 3.93700787 |
| 25 | 9.84251969 |
| 50 | 19.68503937 |
| 100 | 39.37007874 |
How to Use the Free Online Unit Converter
- Pick a category — Length, Weight, Temperature, Volume, Area, Speed, Time, or Data — or tap a popular preset like cm → in, kg → lbs, or °C → °F.
- Enter a value in the From field and choose the source unit. Results update as you type — no submit button required.
- Choose the To unit (or press Swap) to flip direction for bidirectional conversion.
- Read the formula line and the quick reference table for common values of the active pair.
- Copy the result when you need it in a form, recipe, or spreadsheet. Everything runs privately in your browser.
About the Metric & Imperial Unit Converter
ToolGenie's free unit converter helps you switch between metric and imperial measurements for everyday tasks — cooking, fitness tracking, travel distances, shipping dimensions, and file sizes. It targets searches like "unit converter online," "cm to inches," "kg to lbs," and "celsius to fahrenheit" with the category + swap layout people expect from top conversion sites.
Unlike currency converters that need live rates, this page is fully client-side with fixed SI / NIST factors. Pair it with the BMI calculator when you need body metrics, the percentage calculator for percent change, the age calculator for date-based ages, or the loan EMI calculator for finance math.
Need time zones instead of unit math? Use the world time zone converter or the epoch converter. For measuring on screen, try the online ruler.
Common Unit Conversion Formulas
Length: cm to inches & feet to meters
1 inch = 2.54 cm exactly, so inches = cm ÷ 2.54. 1 foot = 0.3048 m, so meters = feet × 0.3048. Miles and kilometers use 1 mi = 1.609344 km.
Weight: kg to lbs & oz to grams
1 pound = 0.45359237 kg, so lbs = kg × 2.2046226218. 1 avoirdupois ounce = 28.349523125 g. Stone (st) equals 14 pounds.
Temperature: Celsius ↔ Fahrenheit ↔ Kelvin
°F = (°C × 9/5) + 32 and °C = (°F − 32) × 5/9. Kelvin = °C + 273.15. Absolute zero is 0 K (−273.15 °C).
Volume, speed & data
1 US gallon = 3.785411784 L. Speed: mph × 1.609344 = km/h. Data sizes here use binary powers of 1024 (1 GB = 1024 MB), matching typical OS file size displays.
Frequently Asked Questions (FAQ)
1. How do I convert centimeters to inches?
Select Length, set From to centimeters (cm) and To to inches (in), then enter your value. The formula is inches = cm ÷ 2.54. For example, 100 cm = 39.370079 in. You can also tap the cm → in preset.
2. How do I convert kg to lbs?
Open the Weight category, choose kilograms (kg) as From and pounds (lb) as To. Multiply kilograms by 2.2046226218 to get pounds. Example: 1 kg ≈ 2.204623 lb. Use Swap to convert lbs to kg.
3. How do I convert Celsius to Fahrenheit?
Select Temperature, From °C and To °F, then enter the temperature. The formula is °F = (°C × 9/5) + 32. Example: 25 °C = 77 °F. Swap units to convert Fahrenheit to Celsius with (°F − 32) × 5/9.
4. How many kilometers are in a mile?
One international mile equals exactly 1.609344 kilometers. In the Length category, convert mi to km (or use the mi → km preset). One kilometer is about 0.621371 miles.
5. How do I convert feet to meters?
Choose Length, From feet (ft) and To meters (m). Multiply feet by 0.3048. Example: 6 ft = 1.8288 m. Swap to convert meters to feet (1 m ≈ 3.28084 ft).
6. How do I convert gallons to liters?
Open Volume, set From to US gallon (gal) and To to liter (L). One US gallon equals 3.785411784 liters. Example: 1 gal ≈ 3.785412 L. Note: this tool uses US liquid gallons, not UK imperial gallons.
7. What is the difference between MB and GB?
In this converter, data sizes use binary units (same as most operating systems): 1 KB = 1024 bytes, 1 MB = 1024 KB, and 1 GB = 1024 MB. So 1024 MB = 1 GB. SI decimal units (1 MB = 1,000,000 bytes) are different and used mainly by storage manufacturers.
8. How do I convert mph to km/h?
Select Speed, From mph and To km/h. Multiply miles per hour by 1.609344. Example: 60 mph = 96.56064 km/h. Swap units to convert km/h to mph.
9. How do I convert ounces to grams?
In Weight, set From to ounces (oz) and To to grams (g). One avoirdupois ounce equals 28.349523125 grams. Example: 8 oz ≈ 226.796185 g.
10. Is this unit converter free, and is my data private?
Yes. ToolGenie's unit converter is free with no signup. All conversions run 100% client-side in your browser — nothing is uploaded to a server, so your numbers stay on your device.
Tips for Accurate Unit Conversion
- Match the unit system to your source — recipes and fitness apps may mix US cups with metric grams; convert each measurement explicitly.
- Watch US vs UK gallons — this tool uses US liquid gallons. UK imperial gallons are larger (~4.546 L).
- Use binary data sizes for OS file sizes — if a drive maker advertises “500 GB,” that is often SI (decimal); your computer may show fewer gibibytes.
- Double-check temperature zero points — Kelvin cannot go below 0; negative Fahrenheit or Celsius is fine for weather and science.
- Combine with related calculators — convert height/weight then open the BMI calculator, or use the percentage calculator after converting currencies or quantities elsewhere.