“Your oven only shows Fahrenheit but the recipe says 150°C” or “an overseas store lists your height as 5 feet 6 inches” - moments like these call for unit conversion.
In this article, we explain how to convert length, weight and temperature units, focusing on the conversions you actually meet in daily life, with concrete examples.
Converting length
Centimeters and inches
Inches are used mainly in the US and UK. Screen sizes are always given in inches.
1 inch = 2.54 centimeters
1 centimeter = about 0.394 inchesExample: the width of a 15.6-inch laptop screen
- 15.6 × 2.54 = about 39.6 cm
Meters and feet
Feet are used for height and aircraft altitude.
1 foot = 0.3048 meters
1 meter = about 3.28 feetExample: height 180 cm
- 180 ÷ 30.48 = about 5.9 feet (5 ft 11 in)
Kilometers and miles
Miles are the standard distance unit in the US. You will meet them on overseas maps and in aviation.
1 mile = 1.609344 kilometers
1 kilometer = about 0.621 milesTip: Instead of memorizing exact factors, learn rough ones - 1 inch ≈ 2.5 cm, 1 foot ≈ 30 cm, 1 mile ≈ 1.6 km. Good enough for most situations.
Converting weight
Kilograms and pounds
Pounds are used in the US and UK. You will see them on foreign recipes and dumbbells.
1 pound = 0.45359237 kilograms
1 kilogram = about 2.205 poundsExample: a 5 kg dumbbell
- 5 × 2.205 = about 11 lb
Grams and ounces
Ounces appear in cooking and precious metals, especially in American recipes.
1 ounce = 28.3495 grams
1 gram = about 0.0353 ouncesExample: an 8 oz steak
- 8 × 28.35 = about 227 g
Converting temperature
Celsius and Fahrenheit
Fahrenheit is used in the US. Weather and cooking are usually Celsius in Japan, so conversion comes up often.
Fahrenheit = Celsius × 9/5 + 32
Celsius = (Fahrenheit − 32) × 5/9| Celsius | Fahrenheit | Reference |
|---|---|---|
| 0°C | 32°F | Water freezes |
| 20°C | 68°F | Comfortable room |
| 37°C | 98.6°F | Human body |
| 100°C | 212°F | Water boils |
Example: 150°C oven setting
- 150 × 9/5 + 32 = 302°F
Kelvin
Kelvin is the scientific scale, starting at absolute zero (0 K).
Kelvin = Celsius + 273.15Example: a room at 20°C is 293.15 K
Caution: Temperature conversion is not plain multiplication. Remember the offset - ×9/5+32 going up, −32×5/9 going down.
How to convert units in seconds
With the Tools Hub unit converter, just pick a category and length, weight, temperature, volume, area and speed are converted instantly.
Pick a category
Choose length, weight, temperature or another category.
Enter the value and unit
Type the number and pick the unit you are converting from.
Read the result
Pick the target unit and the result appears automatically.
The tool introduced in this article
Unit Converter
Covers length, weight, temperature, volume, area and speed. All in your browser with no uploads.
Handy conversion quick reference
| Conversion | Formula |
|---|---|
| Inches → cm | × 2.54 |
| cm → inches | ÷ 2.54 |
| Feet → meters | × 0.3048 |
| Miles → km | × 1.609 |
| Pounds → kg | × 0.4536 |
| Ounces → grams | × 28.35 |
| Celsius → Fahrenheit | C × 9/5 + 32 |
| Celsius → Kelvin | C + 273.15 |
Summary
- Length: 1 inch = 2.54 cm, 1 mile ≈ 1.6 km are the basics
- Weight: remember 1 lb ≈ 453 g and 1 oz ≈ 28 g
- Temperature needs the offset (+32/−32), never just a factor
- Know when an estimate is enough and when you need precision
- The Tools Hub converter handles it all in your browser
Next time you face a foreign recipe or website, use the formulas above or the Tools Hub unit converter.
FAQ
How do I convert inches to centimeters?
Multiply inches by 2.54. To go the other way, divide centimeters by 2.54.
How do I convert Fahrenheit to Celsius?
Use (F − 32) × 5/9. Example: 68°F → (68 − 32) × 5/9 = 20°C.
Which is heavier, pounds or kilograms?
One kilogram is about 2.2 pounds, so at the same number, kilograms are heavier. 5 kg equals about 11 lb.
Which units does the converter support?
Six categories: length, weight, temperature, volume, area and speed.
