Unit Converter - Instant Online Conversions for All Units

A unit converter is an essential online tool that instantly transforms any measurement from one unit to another — no formulas to memorise, no manual arithmetic. Whether you need to convert kilograms to pounds, kilometres to miles, Celsius to Fahrenheit, or litres to US gallons, this free online unit converter handles every common category in real time.

Every conversion uses precise, internationally defined factors aligned with NIST standards. Results update as you type. A formula bar shows the exact expression used — so you can learn the conversion, not just get the number.

Six major categories covered: Length, Weight, Temperature, Area, Volume, and Speed. A full conversion table is generated automatically for every value you enter.

How to Use Our Online Unit Converter

How to Convert Units — 3 Steps

1
Choose a conversion categorySelect from Length, Weight, Temperature, Area, Volume, or Speed using the category tabs. The unit dropdowns update automatically.
2
Select your source and target unitsChoose your source unit (e.g., Kilograms) from the left dropdown and your target unit (e.g., Pounds) from the right. Use the swap button to instantly reverse the direction.
3
Enter your valueType any number. The result, formula, and full conversion table all update instantly — no button press required.

How to Convert KG to LBS Quickly

Select Weight, choose Kilogram and Pound, then enter your value. The exact factor is 1 kg = 2.20462 lbs. Quick reference: 50 kg = 110.23 lbs | 70 kg = 154.32 lbs | 100 kg = 220.46 lbs.

Converting Celsius to Fahrenheit Explained

Select Temperature, choose Celsius and Fahrenheit. Formula: °F = (°C × 9/5) + 32. Temperature is non-linear — you cannot simply multiply by a factor. Key points: 0°C = 32°F | 20°C = 68°F | 37°C = 98.6°F (body temp) | 100°C = 212°F.

Popular Conversions

What is 5 Feet in Centimetres?

5 feet = 152.4 cm. The exact factor is 1 foot = 30.48 cm (international definition since 1959). Height reference: 5 ft 5 in = 165.1 cm | 5 ft 10 in = 177.8 cm | 6 ft = 182.88 cm.

Litres to Gallons for US Users

1 litre = 0.26417 US gallons. The US gallon (3.785 L) and UK imperial gallon (4.546 L) differ by ~20% — always confirm which is required. Quick reference: 5 L = 1.32 US gal | 20 L = 5.28 US gal | 1 US gal = 3.785 L.

Length, Weight & Volume Converter Guide

Scientific and Engineering Unit Conversions

In scientific and engineering work, unit consistency is critical — a single error can invalidate an entire calculation. The SI system defines seven base units: metre (length), kilogram (mass), second (time), ampere (current), kelvin (temperature), mole (substance), and candela (luminosity). All other units are derived from these. This converter handles the most common derived and practical units. For pressure (psi, bar, Pa), energy (joules, calories, BTU), or electrical units, dedicated converters are available in the CalkHub tool library.

Common Unit Conversion Mistakes to Avoid

Frequently Asked Questions

How do I convert kilograms to pounds accurately?

Multiply your kilogram value by 2.20462 to get pounds. For example, 70 kg × 2.20462 = 154.32 lbs. This factor derives from the exact international definition: 1 lb = 0.45359237 kg (NIST). Select Weight in the converter, choose kg as source and lb as target, and enter your value for an instant result.

What is the difference between metric and imperial units?

The metric system (SI) is decimal-based — units scale by powers of ten (1 km = 1,000 m = 100,000 cm). The imperial system uses historically derived units with irregular factors: 12 inches in a foot, 3 feet in a yard, 1,760 yards in a mile. Most countries use metric exclusively; the US uses imperial for everyday use, while the UK uses both.

How accurate is this online unit converter?

This converter uses exact or high-precision coefficients from international standards — for example, 1 mile = 1,609.344 metres exactly and 1 inch = 2.54 cm exactly by international definition since 1959. Results are displayed to up to 8 significant figures. For scientific work requiring maximum precision, verify critical values against primary NIST reference data.

Why do I need a unit converter for baking?

Baking recipes frequently mix metric and imperial — grams and ounces for dry ingredients, millilitres and cups for liquids — and errors cause failures. Key baking conversions: 1 US cup = 236.6 mL, 1 oz = 28.35 g, 1 lb = 453.6 g, 1 tsp = 4.93 mL. Select Volume or Weight in the converter for precise baking results.

How do temperature conversions work between Celsius and Fahrenheit?

Temperature uses a formula, not simple multiplication. To convert: °F = (°C × 9/5) + 32. To reverse: °C = (°F − 32) × 5/9. For Kelvin: K = °C + 273.15. The two scales have different zero points (0°C = 32°F, not 0°F), which is why a single multiplication factor does not work.

What units are used in engineering calculations?

Engineering typically uses SI base units — metres, kilograms, seconds, kelvin — or derived units such as newtons (force), pascals (pressure), joules (energy), and watts (power). US engineering often uses the customary system (feet, pounds, BTU, psi). Always confirm the required unit system from your specification or standard before performing conversions.

Can I convert area and volume for home improvement projects?

Yes. Select Area to convert between square metres, square feet, square yards, hectares, and acres — useful for flooring, tiling, and land measurements. Select Volume for cubic metres, litres, gallons, and cubic feet — useful for concrete, water storage, and paint coverage. For example: 1 m² = 10.764 ft², and 1 m³ = 264.2 US gallons.

How many ounces are in a gallon?

There are 128 US fluid ounces in 1 US gallon (3.785 L). In the UK imperial system, 1 UK gallon = 160 UK fluid ounces (4.546 L). The US and UK gallon differ by approximately 20%, so always confirm which gallon is specified — particularly for fuel economy, recipe scaling, and international shipping.

What is the formula for converting miles to kilometres?

Multiply miles by 1.60934 to get kilometres. The exact international definition is 1 mile = 1,609.344 metres. To reverse: divide km by 1.60934 (or multiply by 0.62137). Example: 60 mph = 96.56 km/h. Select Length or Speed in the converter for instant mile-to-kilometre conversions.

What is 20 Celsius in Fahrenheit?

20°C = 68°F. Using the formula: (20 × 9/5) + 32 = 36 + 32 = 68°F. This is a comfortable room temperature. Other common references: 0°C = 32°F (freezing point), 37°C = 98.6°F (body temperature), 100°C = 212°F (boiling point at sea level). Use the Temperature category in the converter for any Celsius, Fahrenheit, or Kelvin conversion.