Unit Converters
Unit converters turn a value in one measurement unit into its equivalent in another, helping students, engineers, cooks, travelers, and developers swap between metric, imperial, and digital units in seconds.
Free area converter: enter one value and instantly see square meters, square feet, acres, hectares, square inches, yards, km and more using exact factors.
Convert between Celsius, Fahrenheit and Kelvin instantly. Enter any temperature to see all three scales, plus the C to F formula, worked examples and a reference chart from −40°C to 100°C.
Free data storage converter: enter one value and instantly see bits, bytes, KB, MB, GB, TB and PB at once using decimal SI factors where 1 KB = 1000 bytes.
Free fuel economy converter for mpg to l/100km, plus UK MPG and km/L. Enter one figure and see every unit instantly using exact, verified conversion factors.
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards and miles instantly — enter one value and see every unit at once using exact metre-based factors.
Free pressure converter for psi, bar, kPa, atm, mmHg and torr. Convert any pressure unit instantly using exact pascal base factors, accurate to 7 figures.
Free Roman numeral converter: turn any number (1-3999) into Roman numerals and translate Roman numerals back to numbers instantly, using the standard I, V, X, L, C, D, M symbols.
Convert between kilometres per hour, miles per hour, metres per second, feet per second and knots instantly using exact base-unit factors.
Free volume converter for litres, millilitres, cubic metres and US cooking units. Enter one value and see ml, cups, fluid ounces, pints, quarts and gallons at once.
Convert between milligrams, grams, kilograms, metric tonnes, ounces, pounds and stones instantly — enter one value and see every unit at once, using exact NIST conversion factors.
What are unit converters tools?
Unit converters translate a measurement from one unit into an equivalent value in another unit of the same physical quantity, such as temperature, length, mass, speed, area, volume, digital data, pressure, or fuel economy. They remove the need to memorize conversion factors or do error-prone manual math, giving students, engineers, cooks, travelers, and developers quick, accurate results.
Unit Converters tools on Toolzent
Toolzent’s converters cover the units people look up most often. Pick the one that matches your measurement type.
| Tool | What it does |
|---|---|
| Celsius to Fahrenheit Converter | Converts temperatures between degrees Celsius and degrees Fahrenheit in either direction. |
| Length Converter | Converts between length units such as millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles. |
| Weight Converter | Converts between mass and weight units such as grams, kilograms, ounces, pounds, and stones. |
| Speed Converter | Converts between speed units such as kilometers per hour, miles per hour, meters per second, and knots. |
| Area Converter | Converts between area units such as square meters, square feet, acres, and hectares. |
| Volume Converter | Converts between volume units such as liters, milliliters, gallons, quarts, cups, and cubic meters. |
| Data Storage Converter | Converts between digital storage units such as bytes, kilobytes, megabytes, gigabytes, and terabytes. |
| Pressure Converter | Converts between pressure units such as pascals, kilopascals, bar, atmospheres, psi, and millimeters of mercury. |
| Roman Numeral Converter | Converts between Arabic numbers and Roman numerals in either direction, for example 2026 to MMXXVI. |
| Fuel Economy Converter | Converts between fuel economy units such as miles per gallon, kilometers per liter, and liters per 100 km. |
Common unit conversion factors
The factors below are the fixed, standard ratios most converters use, handy for quick mental checks.
| Conversion | Relationship |
|---|---|
| Inches to centimeters | 1 in = 2.54 cm (exact) |
| Miles to kilometers | 1 mi = 1.609344 km |
| Pounds to kilograms | 1 lb = 0.45359237 kg (exact) |
| Gallons (US) to liters | 1 gal = 3.785411784 L |
| Acres to square meters | 1 acre = 4046.8564 sq m |
| Atmospheres to pascals | 1 atm = 101325 Pa |
| Pounds per square inch to kilopascals | 1 psi = 6.89476 kPa |
| Gigabytes to megabytes (SI) | 1 GB = 1000 MB |
| Celsius to Fahrenheit | F = (C x 9/5) + 32 |
Length, weight, volume, area, speed, pressure, and data conversions are simple multiplications by a constant factor, while temperature needs a formula because the scales start from different zero points. Fuel economy is an inverse relationship, so a higher miles-per-gallon figure corresponds to a lower liters-per-100-km figure.
How do I choose the right tool?
Match the tool to the quantity you are measuring:
- Temperatures from a thermostat, recipe, or forecast map to the Celsius to Fahrenheit Converter.
- Distances, heights, and dimensions use the Length Converter for metric and imperial lengths.
- Kilograms, pounds, ounces, and stones go through the Weight Converter.
- Vehicle, wind, or running speeds use the Speed Converter.
- Land, rooms, and floor plans use the Area Converter for square units, acres, and hectares.
- Recipes and container sizes use the Volume Converter for liters, gallons, and cups.
- Files, drives, and bandwidth use the Data Storage Converter for bytes and larger digital units.
- Tire, weather, and engineering pressures use the Pressure Converter for psi, bar, kPa, and atmospheres.
- Clock faces, copyright years, and chapter headings use the Roman Numeral Converter.
- A car’s efficiency across regions uses the Fuel Economy Converter for mpg, km/L, and L/100km.
Why use Toolzent’s unit converters tools?
Toolzent’s unit converters are 100% free with no sign-up and nothing to install. They run privately in your browser, so the numbers you enter stay on your device and are never uploaded. Results appear instantly as you type, the layout is mobile-friendly, and each tool page shows the underlying formula or factor with a worked example. Because the factors match internationally defined constants, the figures match what you would calculate by hand, without the rounding slips.
For related calculations, explore our Math & Algebra, Date, Time & Age, and Statistics category hubs.
Frequently asked questions
Are these unit converters free to use?+
Yes. Every unit converter on Toolzent is 100% free, with no account, sign-up, or download required.
Do I need to install anything or create an account?+
No. The converters run entirely in your web browser, so there is nothing to install and no login to remember.
How accurate are the conversions?+
Conversions use standard, internationally defined factors (for example 1 inch equals exactly 2.54 cm), so results are accurate for everyday and most professional use.
What is the difference between metric and imperial units?+
Metric units (meters, grams, Celsius) are based on powers of ten, while imperial and US customary units (feet, pounds, Fahrenheit) come from older systems; converters translate between the two.
Why does converting Celsius to Fahrenheit need a formula instead of a simple factor?+
Temperature scales have different zero points, so you multiply by 9/5 and add 32 rather than multiplying by a single ratio like you do for length or weight.
Do data storage converters use 1000 or 1024 as the step between units?+
It depends on the standard: decimal SI units step by 1000 (kB, MB, GB) while binary units step by 1024 (KiB, MiB, GiB), which is why advertised and reported sizes can differ.