How many cups fit in a gallon, and how fast is 60 mph in kilometers per hour? The Unit Converter answers questions like these in one step. It handles weight, temperature, volume, and speed.
It suits students, cooks, travelers, and anyone reading a label in the wrong units. You pick a category, type a value, and choose the two units to convert between.
Table of Contents
- What the Unit Converter Does
- How to Use It, Step by Step
- Conversion Factors and Formulas
- Worked Examples
- How to Read the Results
- Choosing Units and Avoiding Mistakes
- Limitations and Assumptions
- FAQs About the Unit Converter
What the Unit Converter Does
The tool offers four categories with four units each. Every conversion in a category passes through one base unit.
- Weight / Mass: kilograms, grams, pounds, and ounces.
- Temperature: Celsius, Fahrenheit, and Kelvin.
- Volume: liters, milliliters, US gallons, and US cups.
- Speed: kilometers per hour, miles per hour, meters per second, and knots.
- Convert Unit runs the conversion and fills the result card.
The result updates as you type, when you change a unit, and when you press Enter in the value box. Changing the category refills both unit lists and converts right away.
How to Use It, Step by Step
- Choose a Category: Weight / Mass, Temperature, Volume, or Speed.
- Type a number in Value. The starting value is 100.
- Pick the unit you have in From.
- Pick the unit you want in To. After a category change, From is the first unit and To is the second.
- Read Converted Value, then the card beside it, labeled Relation or Formula.
- Press Convert Unit if you want to run the conversion again by hand.
Conversion Factors and Formulas
For weight, volume, and speed, the tool first converts your value to the base unit. Then it divides by the base-unit size of the target unit. The base units are kilograms, liters, and kilometers per hour.
Value×From Factor÷To Factor=Converted Value
- Weight, in kg: 1 g = 0.001, 1 lb = 0.45359237, 1 oz = 0.028349523125.
- Volume, in L: 1 mL = 0.001, 1 US gal = 3.785411784, 1 US cup = 0.2365882365.
- Speed, in km/h: 1 mph = 1.609344, 1 m/s = 3.6, 1 knot = 1.852.
Every factor is an exact definition. A US gallon is exactly 231 cubic inches. A cup is one sixteenth of a gallon. A mile is exactly 1.609344 km. The only rounding comes from the display.
Temperature goes through Celsius instead. From Fahrenheit, °C = (°F - 32) × 5 ÷ 9. From Kelvin, °C = K - 273.15. Then °F = °C × 9 ÷ 5 + 32 and K = °C + 273.15.
Worked Examples
Each row shows the tool's own output for the inputs listed.
| Input | Calculation | Converted Value | Relation or Formula |
|---|
| 100 kg to g | 100 × 1 ÷ 0.001 | 100,000 g | 1 kg = 1,000 g |
| 150 lb to kg | 150 × 0.45359237 = 68.0388555 | 68.0389 kg | 1 lb = 0.45359237 kg |
| 2 gal to cup | 2 × 3.785411784 ÷ 0.2365882365 | 32 cup | 1 gal = 16 cup |
| 60 mph to km/h | 60 × 1.609344 = 96.56064 | 96.5606 km/h | 1 mph = 1.609344 km/h |
| 25 °C to °F | 25 × 9 ÷ 5 + 32 | 77 °F | °F = °C × 9/5 + 32 |
The first row is the starting state of the page. The speed row rounds 96.56064 to four decimals, so it reads 96.5606.
How to Read the Results
Converted Value shows up to four decimals and drops trailing zeros. It adds commas, so 100,000.0000 shows as 100,000. A unit symbol follows the number, such as kg, lb, °C, gal, km/h, m/s, or kn.
Tiny results keep at least four significant digits, so 0.00001 g reads 0.00000001 kg. The tool never switches to exponent form. If the entry is blank or not a number, a red message appears and both cards read N/A.
Relation shows what one From unit equals, with up to ten significant digits. An example is 1 lb = 0.45359237 kg. For temperature the card is labeled Formula and shows the equation used.
Choosing Units and Avoiding Mistakes
The gallon and cup here are US customary units. A UK gallon holds about 4.55 liters, so do not use this tool for imperial recipes. The ounce is a unit of weight, not a fluid ounce.
This tool never mixes volume and weight. For length or area, use the Length Converter or the Area Converter.
The temperature option converts readings, not temperature changes. A change of 10 degrees Celsius equals a change of 18 degrees Fahrenheit. Use the Temperature Converter if you want all three scales at once.
Work with milligrams or stone fits the Weight Converter. For more speed or volume units, try the Speed Converter and the Volume Converter. The full set lives in the unit and time converters hub.
Limitations and Assumptions
- Weight, volume, and speed must be 0 or more, and no more than 1,000,000,000,000,000. Temperature has its own limits, covered in the FAQs below.
- Each category has only the units listed above. There is no milligram, stone, fluid ounce, or UK gallon.
- Choosing the same unit in From and To is allowed and returns your value.
- The relation card shows ten significant digits at most, so a long ratio can look trimmed.
FAQs About the Unit Converter
What happens if I enter a temperature below absolute zero?
The tool shows a red message and N/A on both cards. The lowest accepted values are -273.15 °C, -459.67 °F, and 0 K. Exactly absolute zero is accepted.
What is the largest value I can enter?
For weight, volume, and speed it is 1,000,000,000,000,000. For temperature it is 1,000,000,000,000. Larger numbers get a message instead of a result.
Does the tool convert length, area, or pressure?
No. It offers weight, temperature, volume, and speed only. Other units need a separate converter.
Is a knot the same as a mile per hour?
No. A knot is one nautical mile per hour, or exactly 1.852 km/h. That is about 1.15 mph.
Can I convert a cup of flour to grams here?
No. Flour, sugar, and water all weigh different amounts per cup. A weight and volume tool needs a density for each food.
Why does the Formula card say Same scale, no change?
That appears when From and To are the same temperature scale. The result simply repeats your value.
This calculator gives general estimates only and is not professional advice. Reviewed for general accuracy by Prof. Dr. Khalil Mudassar, PhD.