Home › Unit Converters

All Unit Converters

Convert units quickly and accurately with the free online unit converters from Smart Unit Calc. Convert weight, area, volume, temperature, speed, time, pressure, energy, power, force, frequency, digital data and more between common metric, SI, US customary and imperial units.

Choose a converter below or search for the measurement you need. Each converter is designed for quick calculations with clear formulas, conversion factors, examples and useful explanations.

No matching converter found. Try another measurement or unit name.

Popular Unit Converters

Weight Converter kg, lbs, pounds, grams, ounces and more Temperature Converter Celsius, Fahrenheit, Kelvin and more Area Converter m², ft², acres, hectares and more Volume Converter Liters, gallons, cups, mL and cubic units Speed Converter km/h, mph, m/s, knots and more Time Converter Seconds, minutes, hours, days and more

Mass & Weight

Weight & Mass Converter Convert kilograms, pounds, grams, ounces, tonnes and more. kg to lbs & lbs to kg Quick kilogram and pound conversion.

Temperature

Temperature Converter Celsius, Fahrenheit, Kelvin, Rankine and more.

Area

Area Converter Square meters, square feet, acres, hectares and more. Square Meters ↔ Square Feet Convert m² to ft² and ft² to m². Acres & Hectares Converter Convert acres, hectares and land measurements.

Volume & Capacity

Volume Converter Liters, gallons, milliliters, cups and cubic units. Liters ↔ Gallons Convert liters to US or Imperial gallons. Cubic Meters ↔ Cubic Feet Convert m³ and ft³ for volume calculations.

Speed

Speed Converter km/h, mph, m/s, knots and other speed units. km/h ↔ mph Convert kilometers per hour and miles per hour. Knots Converter Convert knots to km/h, mph and other speed units.

Time

Time Converter Nanoseconds, seconds, minutes, hours, days and years. Seconds ↔ Minutes Convert seconds to minutes and minutes to seconds. Hours ↔ Minutes Convert hours and minutes quickly.

Pressure

Pressure Converter PSI, bar, kPa, MPa, atm, Torr, mmHg and more. PSI ↔ Bar Convert pounds per square inch to bar. PSI ↔ kPa Convert PSI and kilopascals.

Energy

Energy Converter Joules, kWh, calories, BTU, electronvolts and more. Joules ↔ kWh Convert joules and kilowatt-hours. kWh ↔ BTU Convert electrical energy to BTU and back.

Power

Power Converter Watts, kW, MW, horsepower, BTU/h and more. Watts ↔ kW Convert watts and kilowatts. Horsepower ↔ kW Convert mechanical or metric horsepower and kilowatts.

Force

Force Converter Newtons, kN, lbf, kgf, dynes and more. Newtons ↔ Pounds-force Convert N to lbf and lbf to N. Newtons ↔ kgf Convert newtons and kilogram-force.

Frequency

Frequency Converter Hz, kHz, MHz, GHz, RPM, RPS and rad/s. Hz ↔ kHz Convert Hertz and kilohertz. MHz ↔ GHz Convert megahertz and gigahertz.

Digital Data & Storage

Data Converter Bits, bytes, KB, MB, GB, TB and binary units. Digital Storage Converter KB, MB, GB, TB, KiB, MiB, GiB and TiB. Data Transfer Converter Mbps, Gbps, Kbps, MB/s, GB/s and more.

More Unit Converter Categories

Length Converter Meters, feet, inches, miles, kilometers and more. Angle Converter Degrees, radians, gradians, turns and angular units. Density Converter Convert common mass-density measurement units. Acceleration Converter Convert acceleration measurement units. Flow Rate Converter Convert liquid and gas flow rate units. Fuel Consumption Converter MPG, L/100 km, km/L and fuel economy units. Torque Converter Convert N·m, lb·ft and other torque units. Electric Charge Converter Convert coulombs and electrical charge units. Illuminance Converter Lux, foot-candles and lighting measurement units.

Free Online Unit Converters

Smart Unit Calc provides a growing collection of free online unit conversion tools for everyday measurements, education, engineering, science, construction, technology and business. Unit converters make it easier to change a measurement from one unit system to another without manually calculating conversion factors.

Whether you need to convert kilograms to pounds, meters to feet, liters to gallons, Celsius to Fahrenheit, kilometers per hour to miles per hour, PSI to bar, watts to kilowatts or GB to TB, Smart Unit Calc provides dedicated conversion tools for common measurement needs.

What Is Unit Conversion?

Unit conversion is the process of expressing the same physical quantity using a different measurement unit. The quantity does not change; only the numerical representation changes.

For example, one kilometer represents the same distance as 1,000 meters. Likewise, one kilogram is equivalent to approximately 2.20462 pounds. A unit converter applies the appropriate conversion relationship to produce the equivalent value.

Types of Unit Converters

Category Common Units Typical Uses
Weight & Mass kg, lb, g, oz, tonne Shipping, cooking, science, everyday measurements
Length m, km, ft, in, yd, mi Construction, travel, engineering, distance
Area m², ft², acre, hectare Land, property, construction and real estate
Volume L, mL, gal, ft³, m³ Cooking, fuel, tanks, containers and engineering
Temperature °C, °F, K, °R Weather, science, HVAC and engineering
Speed km/h, mph, m/s, knots Vehicles, aviation, marine and physics
Time seconds, minutes, hours, days Scheduling, science, productivity and calculations
Pressure Pa, kPa, MPa, bar, psi Hydraulics, pneumatics, tires, HVAC and engineering
Energy J, kJ, MJ, kWh, BTU Physics, electricity, heating and energy analysis
Power W, kW, MW, hp, BTU/h Motors, generators, appliances and engineering
Force N, kN, lbf, kgf Physics, structural and mechanical engineering
Frequency Hz, kHz, MHz, GHz, RPM Electronics, radio, audio, motors and science
Digital Data bit, byte, KB, MB, GB, TB Computers, files, storage and technology
Data Transfer Kbps, Mbps, Gbps, MB/s Internet, networking and file transfers

Metric, SI, US Customary and Imperial Units

Unit conversion often involves different measurement systems. The metric system uses decimal scaling and includes SI units such as meters, kilograms and seconds. US customary and Imperial units include measurements such as feet, inches, miles, pounds, gallons and Fahrenheit.

Some units with similar names are not identical. For example, a US liquid gallon and an Imperial UK gallon have different volumes. Smart Unit Calc identifies important unit-system differences where they affect the conversion.

Unit Conversion for Engineering and Technical Work

Unit converters are useful for engineering calculations involving pressure, force, power, energy, speed, frequency, volume, area, mass and other physical quantities.

For professional engineering, construction and safety-critical applications, converted values should always be checked against the applicable project specifications, standards, manufacturer documentation and engineering calculations.

How to Use a Unit Converter

  1. Select the unit converter you need.
  2. Enter the numerical value.
  3. Select the original unit.
  4. Select the unit you want to convert to.
  5. Review the converted result.

Most Smart Unit Calc converters also provide conversion formulas, examples, common conversion values and explanations of the units involved.

Common Unit Conversion Searches

Popular searches include: kg to lbs, lbs to kg, square meters to square feet, square feet to square meters, liters to gallons, gallons to liters, km/h to mph, mph to km/h, PSI to bar, joules to kWh, watts to kW, newtons to pounds, Hz to kHz, GB to TB and Mbps to MB/s.

Frequently Asked Questions About Unit Converters

What is a unit converter?
A unit converter is an online tool that converts a measurement from one unit into another equivalent unit, such as kilograms to pounds, meters to feet, liters to gallons or Celsius to Fahrenheit.
Are the Smart Unit Calc converters free?
Yes. Smart Unit Calc provides free online unit conversion tools for common measurement categories.
What types of units can I convert?
Smart Unit Calc provides converters for weight, temperature, area, volume, speed, time, pressure, energy, power, force, frequency, data, digital storage and data transfer rates, with additional categories planned.
What is the difference between metric and imperial units?
Metric units are based primarily on the International System of Units and decimal scaling, while imperial and US customary systems use different historical units and relationships.
How accurate are unit conversions?
Conversions use defined unit relationships and formulas. Displayed precision can vary depending on the unit and the limitations of normal browser numerical calculations.
Can I convert metric units to imperial units?
Yes. Many Smart Unit Calc converters support conversions between metric, US customary and imperial units.
What is the difference between mass and weight?
Mass measures the amount of matter and is commonly expressed in kilograms, while weight is a force caused by gravity and is commonly expressed in newtons.
What is the difference between data size and data transfer rate?
Data size measures an amount of digital information, such as MB or GB. Data transfer rate measures how quickly information moves, such as Mbps or MB/s.
Why are US and UK gallons different?
The US liquid gallon and Imperial UK gallon are different historical units. A US gallon is approximately 3.785 liters, while an Imperial gallon is approximately 4.546 liters.
Can unit converters be used for engineering calculations?
Yes. Unit converters can help with engineering, physics, construction and technical calculations, but important design or safety decisions should use applicable technical standards and verified calculations.