How to Use the Unit Converter
Four categories, two unit menus, and a live result — no submit button required.
- Choose Length, Weight / Mass, Volume, or Temperature from the category tabs.
- Enter the value you want to convert, then pick From and To units (for example centimeters and inches, or kilograms and pounds).
- Read the large converted value and the one-line formula under it. Use the swap control to reverse the pair instantly.
- On Volume, the “US units” badge means cups, spoons, fluid ounces, and gallons follow US customary sizes — not Imperial UK gallons.
Common Conversions
Frequently searched pairs and their exact factors — a quick reference alongside the interactive converter.
| From | Equals | Category |
|---|---|---|
| 1 cm | 0.393701 in (inches) | Length |
| 1 inch | 2.54 cm (centimeters) | Length |
| 1 m | 3.28084 ft (feet) | Length |
| 1 mile | 1.60934 km (kilometers) | Length |
| 1 km | 0.621371 mi (miles) | Length |
| 1 kg | 2.20462 lb (pounds) | Weight |
| 1 lb | 0.453592 kg (kilograms) | Weight |
| 1 oz | 28.3495 g (grams) | Weight |
| 1 L | 0.264172 gal (US gallons) | Volume |
| 1 US gal | 3.78541 L (liters) | Volume |
| 1 US cup | 236.588 ml (milliliters) | Volume |
| 0 °C | 32 °F (Fahrenheit) | Temperature |
Metric vs. Imperial / US Customary Units
Two everyday measurement families — and why volume labels matter.
The metric system (SI) builds on meters, kilograms, and liters with powers of ten — centimeters, millimeters, grams, and milliliters stay easy to scale. Most of the world uses metric for science, medicine, and daily life.
Imperial and US customary units (inches, feet, miles, pounds, cups, gallons) share history but are not always identical. The US gallon and US cup differ from Imperial (UK) sizes. This metric to imperial converter keeps cooking and liquid measures on US customary defaults so a “cup” or “gallon” matches typical US packaging and recipes.
Temperature sits apart: Celsius and Kelvin are metric-aligned, while Fahrenheit remains common in the United States. Convert between them with the Temperature tab rather than a simple multiply-by factor.
Frequently Asked Questions
Cups vs metric cups, gallons, Celsius to Fahrenheit, and accuracy.
How do I convert length, weight, or volume units?
Pick a category (Length, Weight / Mass, or Volume), enter a value, choose the From and To units, and read the live result. Use the swap button to flip the pair — useful for cm to inches, kg to lbs, miles to km, liters to gallons, and similar everyday conversions.
How do I convert Celsius to Fahrenheit?
Open the Temperature category, set From to °C and To to °F, then enter the temperature. The formula is °F = °C × 9/5 + 32. The converter also supports Fahrenheit to Celsius and Kelvin both ways.
What is the difference between a US cup and a metric cup?
A US customary cup is about 236.6 milliliters. A metric cup (common in some recipes and countries) is 250 milliliters. They are not the same. This converter uses US cups, teaspoons, tablespoons, fluid ounces, and gallons — look for the “US units” label on the Volume tab.
Why are there different gallon sizes?
The US liquid gallon is about 3.785 liters. The Imperial (UK) gallon is larger — about 4.546 liters. Recipes, fuel, and product labels can use either system depending on the country. CalcDaily defaults to the US gallon so US cooking and packaging conversions stay consistent; Imperial gallons are not mixed into the same dropdown.
Is this converter accurate for scientific or engineering use?
Factors follow standard SI and US customary definitions, and results are rounded for readable everyday use (cooking, schoolwork, travel). For lab or engineering work that needs many significant figures or uncertainty analysis, use a dedicated scientific tool and treat these displays as rounded convenience values.
Can I convert metric to imperial units?
Yes. Length, weight, and volume each include metric units (such as cm, m, kg, liters) and common imperial / US customary units (inches, feet, miles, pounds, US cups and gallons). Temperature covers Celsius, Fahrenheit, and Kelvin on the same panel.
Why can’t I enter a negative length or weight?
Physical lengths, masses, and volumes cannot be negative, so the converter shows a short message instead of a fake result. Temperature is different: Celsius and Fahrenheit may be negative, while Kelvin cannot go below absolute zero (0 K).
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