How Unit Conversion Works
Most unit conversions work by multiplying through a base unit. For length, the meter is the SI base unit. To convert feet to kilometers, the calculator converts feet to meters first (multiply by 0.3048) then meters to kilometers (divide by 1000). Temperature is the exception — it uses an offset formula rather than simple multiplication because the scales have different zero points.
The three key formulas for temperature conversion are:
Fahrenheit → Celsius: °C = (°F − 32) × 5/9
Celsius → Kelvin: K = °C + 273.15
Length Conversion Reference
| From | To Meters | To Feet | To Inches | To Kilometers | To Miles |
|---|---|---|---|---|---|
| 1 meter | 1 | 3.2808 | 39.37 | 0.001 | 0.000621 |
| 1 foot | 0.3048 | 1 | 12 | 0.000305 | 0.000189 |
| 1 kilometer | 1,000 | 3,280.8 | 39,370 | 1 | 0.6214 |
| 1 mile | 1,609.3 | 5,280 | 63,360 | 1.6093 | 1 |
| 1 inch | 0.0254 | 0.0833 | 1 | 0.0000254 | 0.0000158 |
Weight & Mass Conversion Reference
| From | To Kilograms | To Pounds | To Ounces | To Grams |
|---|---|---|---|---|
| 1 kilogram | 1 | 2.2046 | 35.274 | 1,000 |
| 1 pound | 0.4536 | 1 | 16 | 453.59 |
| 1 ounce | 0.02835 | 0.0625 | 1 | 28.35 |
| 1 stone | 6.3503 | 14 | 224 | 6,350 |
Temperature Quick Reference
| Description | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Absolute zero | −273.15°C | −459.67°F | 0 K |
| Water freezes | 0°C | 32°F | 273.15 K |
| Room temperature | 20–22°C | 68–72°F | 293–295 K |
| Body temperature | 37°C | 98.6°F | 310.15 K |
| Water boils | 100°C | 212°F | 373.15 K |
Volume Conversion Reference
| From | To Liters | To Gallons (US) | To Cups | To Fluid Oz |
|---|---|---|---|---|
| 1 liter | 1 | 0.2642 | 4.2268 | 33.814 |
| 1 gallon (US) | 3.7854 | 1 | 16 | 128 |
| 1 cup | 0.2366 | 0.0625 | 1 | 8 |
| 1 fluid oz | 0.02957 | 0.00781 | 0.125 | 1 |
| 1 milliliter | 0.001 | 0.000264 | 0.00423 | 0.03381 |
Metric vs. Imperial: Why Two Systems?
The metric system (SI) was developed in France in the 1790s and is now the global standard for science, medicine, and everyday life in nearly every country. The United States, Liberia, and Myanmar are the only three countries that have not officially adopted the metric system as their primary measurement system, though the US uses metric extensively in science, medicine, and the military.
The imperial system evolved from older English measures and uses relationships that were practical before decimalization: 12 inches in a foot, 3 feet in a yard, 5,280 feet in a mile. These numbers make mental fractions like "half a yard" or "a quarter mile" easy, but make arithmetic between units cumbersome.