Free Online Converters 2026 — Unit, Temperature, Currency & More

Q: How do I convert Celsius to Fahrenheit?

Formula: F = (C x 9/5) + 32. Example: 20C = 68F. Reverse: C = (F - 32) x 5/9. Use the Temperature Converter for instant results.

Q: How many kilograms are in a pound?

One pound equals exactly 0.45359237 kilograms. One kilogram equals approximately 2.20462 pounds. One stone equals 14 lbs or 6.35 kg.

Q: How many centimeters are in an inch?

One inch equals exactly 2.54 centimeters by international definition since 1959. One foot equals 30.48 cm. One meter equals 39.3701 inches.

Q: How do I convert miles per hour to kilometers per hour?

Multiply mph by 1.60934 to get km/h. Example: 60 mph equals 96.56 km/h. To convert km/h to mph, multiply by 0.62137. One knot equals 1.852 km/h.

Q: How many liters are in a US gallon?

One US gallon equals exactly 3.78541 liters. The UK imperial gallon is larger at 4.54609 liters. One liter equals 4.22675 US cups.

Q: How do I convert acres to square meters?

One acre equals 4,046.86 square meters or approximately 0.4047 hectares. One hectare equals 2.471 acres and 10,000 square meters.

Q: How many megabytes are in a gigabyte?

In the decimal SI system: 1 GB equals 1,000 MB. In the binary system: 1 GiB equals 1,024 MiB. This explains why a 1 TB drive shows as 931 GB in Windows.

Q: What is HEX color and how do I convert it to RGB?

HEX color is a six-digit code where each pair represents red, green and blue in hexadecimal (00 to FF = 0 to 255). #FF5733 converts to rgb(255, 87, 51).

Q: How often are currency exchange rates updated?

Currency rates are updated daily from open market data reflecting the mid-market rate. For financial transactions, confirm the exact rate with your bank as they add a spread.

Q: What is the difference between mass and weight?

Mass is the amount of matter in kilograms. Weight is gravitational force in newtons. On Earth they are proportional. On the Moon you weigh one sixth as much but your mass is unchanged.

All Converters

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Unit Converter

The all-in-one converter. Switch between length, weight, temperature, volume, area and speed in one place. The most-used converter on the web.

Length Weight Temperature Volume Area Speed

5M+ monthly searches

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Temperature Converter

Convert instantly between Celsius, Fahrenheit and Kelvin. Essential for cooking, science and travel.

°C °F K

3M+ monthly searches

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Length Converter

Convert between metric and imperial length units. Centimeters, meters, kilometers, inches, feet, yards and miles.

cm m km in ft mi

2M+ monthly searches

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Weight Converter

Convert between kilograms, pounds, stone, ounces and grams. Covers both metric and imperial weight systems.

kg lbs stone oz g

1.5M+ monthly searches

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Currency Converter

Real-time exchange rates for 150+ currencies. USD, EUR, GBP, JPY, CAD, AUD and more. Powered by live market data.

USD EUR GBP JPY +150

10M+ monthly searches

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Speed Converter

Convert between kilometers per hour, miles per hour, meters per second, knots and other speed units.

km/h mph m/s knots

500K+ monthly searches

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Area Converter

Convert square meters, square feet, acres, hectares and more. Useful for real estate, gardening and land measurement.

m² ft² acres ha

400K+ monthly searches

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Volume Converter

Convert liters, gallons, cups, fluid ounces, milliliters and other volume units. Perfect for cooking and liquid measurement.

L gal cups fl oz ml

400K+ monthly searches

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Data Storage Converter

Convert between bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes. Essential for developers and IT professionals.

B KB MB GB TB

300K+ monthly searches

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Color Converter

Convert between HEX, RGB, HSL and HSB color formats. Indispensable for designers and frontend developers.

HEX RGB HSL HSB

600K+ monthly searches

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Pressure Converter

Convert between pascals, bar, PSI, atmospheres, mmHg and other pressure units. Used in science, engineering and weather.

Pa bar PSI atm mmHg

350K+ monthly searches

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Calendar Converter

Convert any date between Gregorian, Julian, Islamic (Hijri), Hebrew, Persian, Ethiopian, Coptic, Byzantine, Maya Long Count and more.

Gregorian Julian Islamic Hebrew Maya

10+ Calendar Systems

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Why Use Our Free Converters?

Every converter on CalculatorsHub works instantly in your browser, with no forms to submit, no accounts to create and no data stored on our servers. Results update as you type.

Our unit conversion factors are sourced from the International System of Units (SI) and the National Institute of Standards and Technology (NIST). Currency rates are refreshed daily from live market feeds. All converters are updated for 2026.

Metric & Imperial

Every converter covers both metric (SI) and imperial/US customary units so you get the right answer regardless of your location.

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Converter Questions

How do I convert Celsius to Fahrenheit?+

Multiply the Celsius value by 9, divide by 5, then add 32. Formula: °F = (°C × 9/5) + 32. Example: 20°C = (20 × 9/5) + 32 = 68°F. To go the other way: °C = (°F − 32) × 5/9. Use our Temperature Converter for instant results without manual calculation.

How many kilograms are in a pound?+

One pound (lb) equals exactly 0.45359237 kilograms. Conversely, one kilogram equals approximately 2.20462 pounds. To convert pounds to kg, multiply by 0.4536. To convert kg to pounds, multiply by 2.2046. Our Weight Converter handles all weight units including stone (1 stone = 14 lbs = 6.35 kg) and ounces (1 oz = 28.35 g).

How many centimeters are in an inch?+

One inch equals exactly 2.54 centimeters, by international definition since 1959. So 1 foot (12 inches) = 30.48 cm, and 1 meter = 39.3701 inches. To convert inches to centimeters, multiply by 2.54. To convert centimeters to inches, divide by 2.54. Our Length Converter covers all common length units including miles, yards, feet, inches, meters and kilometers.

How do I convert miles per hour to kilometers per hour?+

Multiply miles per hour (mph) by 1.60934 to get kilometers per hour (km/h). Example: 60 mph = 96.56 km/h. To convert km/h to mph, multiply by 0.62137. Other common conversions: 1 m/s = 3.6 km/h = 2.237 mph. 1 knot = 1.852 km/h = 1.151 mph. Our Speed Converter handles all of these instantly.

How many liters are in a US gallon?+

One US gallon equals exactly 3.78541 liters. Note: the UK (imperial) gallon is larger at 4.54609 liters. Other common volume conversions: 1 liter = 4.22675 US cups = 33.814 fl oz. 1 US cup = 236.588 ml. Our Volume Converter distinguishes between US and UK measurements to avoid confusion.

How do I convert acres to square meters?+

One acre equals 4,046.86 square meters, or approximately 0.4047 hectares. Conversely, 1 hectare = 2.471 acres = 10,000 m². One square foot = 0.0929 m². These conversions are used frequently in real estate and land measurement. Our Area Converter supports acres, hectares, square meters, square feet, square miles and square kilometers.

How many megabytes are in a gigabyte?+

In the decimal (SI) system used by hard drive manufacturers: 1 GB = 1,000 MB = 1,000,000 KB = 1,000,000,000 bytes. In the binary system used by operating systems: 1 GiB (gibibyte) = 1,024 MiB = 1,048,576 KiB = 1,073,741,824 bytes. This difference explains why a 1 TB hard drive shows as 931 GB in Windows. Our Data Storage Converter uses the decimal (SI) system.

What is HEX color and how do I convert it to RGB?+

HEX color is a six-digit hexadecimal code (e.g. #FF5733) representing the red, green and blue channels of a color. Each pair of digits (FF, 57, 33) is a hex number from 00 to FF (0 to 255 in decimal). To convert to RGB: R=255, G=87, B=51. To convert RGB to HEX, convert each value to hex and concatenate. Our Color Converter handles HEX, RGB, HSL and HSB automatically.

How often are currency exchange rates updated?+

Our Currency Converter uses exchange rates updated daily from open market data sources. Rates reflect the mid-market rate (the midpoint between buy and sell rates). For financial transactions, always confirm the exact rate with your bank or exchange service, as they add a spread. The mid-market rate shown here is the fairest reference point for comparison.

What is the difference between mass and weight?+

Mass is the amount of matter in an object, measured in kilograms or pounds-mass. Weight is the gravitational force on that mass, measured in newtons. On Earth's surface they are proportional, so in everyday use (and on our converter) kilograms and pounds are used interchangeably for both. On the Moon you would weigh about 1/6th as much but your mass would be unchanged. Our Weight Converter uses the everyday convention.