Free Unit Converter Online — Length, Mass, Temperature, Volume, Area & Speed
How many kilometers in a mile? How many ounces in a liter? What is 180°F in Celsius? These are questions people search for hundreds of millions of times per year. Unit conversion is one of the most fundamental everyday math tasks — whether you are cooking with a recipe from another country, calculating shipping weights, converting between metric and imperial for work, or checking weather temperatures while traveling.
The Unit Converter on OnlineToolHubs handles six major measurement categories with exact conversion factors (not approximations), so you can trust every result. It runs in your browser, works on any device, and requires no signup.
What Does the Unit Converter Cover?
📏 Length & Distance
Convert between meters, kilometers, miles, feet, inches, yards, centimeters, millimeters, nautical miles, and more.
| From | To | Factor |
|---|---|---|
| 1 mile | kilometers | 1.60934 km |
| 1 foot | centimeters | 30.48 cm |
| 1 inch | centimeters | 2.54 cm (exact) |
| 1 meter | feet | 3.28084 ft |
| 1 yard | meters | 0.9144 m (exact) |
⚖️ Mass & Weight
Convert between kilograms, pounds, ounces, grams, milligrams, stones, metric tons, and more.
| From | To | Factor |
|---|---|---|
| 1 pound | kilograms | 0.453592 kg |
| 1 kilogram | pounds | 2.20462 lbs |
| 1 ounce | grams | 28.3495 g |
| 1 stone | kilograms | 6.35029 kg |
🌡️ Temperature
Convert between Celsius, Fahrenheit, and Kelvin.
| From | To | Formula |
|---|---|---|
| °C → °F | Fahrenheit | (°C × 9/5) + 32 |
| °F → °C | Celsius | (°F - 32) × 5/9 |
| °C → K | Kelvin | °C + 273.15 |
🫗 Volume
Convert between liters, gallons, cups, tablespoons, teaspoons, milliliters, fluid ounces, pints, quarts, and more.
📐 Area
Convert between square meters, square feet, acres, hectares, square kilometers, square miles, and more.
🏎️ Speed
Convert between mph, km/h, m/s, knots, and more.
How to Use the Unit Converter: Step-by-Step
Step 1: Select a Category
Choose from Length, Mass, Temperature, Volume, Area, or Speed.
Step 2: Choose Your Units
Select the “from” unit and the “to” unit from the dropdown menus.
Step 3: Enter Your Value
Type the number you want to convert. The result appears instantly.
Step 4: Verify the Conversion Factor
The tool displays the exact conversion factor used, so you can verify the math or learn the factor for future reference.
Common Unit Conversions People Search For
| Search Query | Answer |
|---|---|
| How many km in a mile? | 1 mile = 1.60934 km |
| How many cups in a liter? | 1 liter = 4.22675 cups |
| How many pounds in a kg? | 1 kg = 2.20462 lbs |
| What is 0°C in Fahrenheit? | 0°C = 32°F |
| How many ounces in a pound? | 1 pound = 16 ounces |
| How many feet in a meter? | 1 meter = 3.28084 feet |
| What is 100°F in Celsius? | 100°F = 37.78°C |
| How many ml in a tablespoon? | 1 tbsp = 14.787 ml |
| How many inches in a centimeter? | 1 cm = 0.393701 inches |
| How many grams in an ounce? | 1 oz = 28.3495 grams |
All of these are answered instantly by the OnlineToolHubs Unit Converter.
Who Uses Unit Converters?
- Students — Physics, chemistry, and engineering homework constantly requires unit conversions
- Travelers — Converting temperatures, distances, and weights between metric and imperial systems
- Cooks — Converting recipe measurements between cups, milliliters, ounces, and grams
- Engineers — Converting between SI and imperial units for technical specifications
- Fitness enthusiasts — Converting body weight between kg and lbs, distances between km and miles
- Real estate — Converting square footage to square meters or acres
- Shipping & logistics — Converting weights and dimensions for international shipments
Unit Converter vs. Google vs. Siri/Alexa
| Feature | OnlineToolHubs | Google Search | Siri/Alexa |
|---|---|---|---|
| All categories in one place | ✅ | ⚠️ One at a time | ⚠️ One at a time |
| Shows conversion factor | ✅ | ❌ | ❌ |
| Works offline (after load) | ✅ | ❌ | ❌ |
| No tracking | ✅ | ❌ Tracked | ❌ Tracked |
| Exact factors (not rounded) | ✅ | ✅ | ⚠️ Often rounded |
| Multiple conversions quickly | ✅ | ⚠️ New search each time | ⚠️ One at a time |
Try the Unit Converter Now — Free, No Signup Required
Convert between metric and imperial, Celsius and Fahrenheit, liters and gallons, and hundreds of other unit pairs with exact conversion factors.
👉 Use the Free Unit Converter on OnlineToolHubs — No account. Exact factors. Works offline after loading.
Frequently Asked Questions
How do I convert units online?
Use the Unit Converter on OnlineToolHubs — select the category, choose your units, enter a value, and get instant results with exact conversion factors.
How many centimeters are in an inch?
One inch equals exactly 2.54 centimeters. This is an exact definition, not an approximation.
What is the formula to convert Celsius to Fahrenheit?
°F = (°C × 9/5) + 32. For example, 25°C = 77°F.
Does this unit converter work offline?
Yes. Since it runs entirely in your browser, it continues working after the page loads even without an internet connection.