A unit converter instantly switches between metric, imperial, and traditional measurement systems — no manual calculation needed. The world runs on two measurement systems — the metric system (used by most of the world) and the imperial/US customary system (used by the US and Myanmar, with the UK using a mix). India officially adopted the metric system in 1957, but imperial units persist in real estate (acres, yards), cooking (cups, ounces), and everyday speech ("he's 5 feet 10 inches tall").
This guide is your complete unit conversion reference. It covers length, weight, temperature, volume, and area conversions with exact formulas, quick-reference tables for the most commonly searched pairs, and a section on India-specific units that most unit converter guides ignore entirely.
Convert Any Unit — Free, Instant, No Signup
Length, weight, temperature, volume, area, speed and more. Supports metric, imperial, and India-specific units including acres, tola, bigha, and more.
Metric vs Imperial: Why Two Systems Exist
The metric system (SI — International System of Units) was developed during the French Revolution and is based on powers of 10, making calculations straightforward. The imperial system evolved from English medieval units, each defined independently — a foot was literally the length of a human foot.
Which countries use which system?
- Metric only: Almost every country in the world — India, China, EU, Australia, Canada (mostly)
- Imperial/US customary: United States (officially), Liberia, Myanmar
- Mixed: United Kingdom (metric for most purposes; miles, pounds, and pints persist culturally)
Why unit conversion matters
You need unit conversion when: reading US recipe measurements (cups, Fahrenheit), buying property described in acres or yards, understanding vehicle fuel efficiency (mpg vs L/100km), interpreting international product specs, travelling between countries, and following US-based fitness or nutrition content.
In 1999, NASA lost a ₹3,000 crore ($327 million) spacecraft because one engineering team sent thruster force data in pound-force·seconds while another team expected newton·seconds. The unit mismatch caused the probe to enter Mars' atmosphere at the wrong angle. Unit conversion errors have real consequences.
Length Conversions: Meters, Feet, Inches, Miles and More
Length conversion is the most-searched unit conversion category globally, driven by height comparisons ("how tall is 5'11" in cm"), travel distances, and construction measurements.
Key length conversion formulas
| Convert From | Convert To | Formula | Example |
|---|---|---|---|
| Metres | Feet | × 3.28084 | 1.75 m = 5.741 ft ≈ 5'9" |
| Feet | Metres | × 0.3048 | 6 ft = 1.829 m |
| Inches | Centimetres | × 2.54 | 12 in = 30.48 cm |
| Centimetres | Inches | × 0.3937 | 100 cm = 39.37 in |
| Kilometres | Miles | × 0.62137 | 10 km = 6.214 miles |
| Miles | Kilometres | × 1.60934 | 5 miles = 8.047 km |
| Yards | Metres | × 0.9144 | 100 yards = 91.44 m |
Height reference table (feet/inches to cm)
| Height (ft/in) | Height (cm) | Height (ft/in) | Height (cm) |
|---|---|---|---|
| 5'0" | 152.4 cm | 5'8" | 172.7 cm |
| 5'2" | 157.5 cm | 5'10" | 177.8 cm |
| 5'4" | 162.6 cm | 6'0" | 182.9 cm |
| 5'6" | 167.6 cm | 6'2" | 187.9 cm |
Weight Conversions: kg, lbs, grams, ounces and More
Weight conversions are critical for fitness (gym equipment in lbs vs gym guides in kg), cooking (US recipes in ounces vs metric), and international shipping.
Key weight conversion formulas
| Convert From | Convert To | Formula | Example |
|---|---|---|---|
| Kilograms | Pounds | × 2.20462 | 70 kg = 154.3 lbs |
| Pounds | Kilograms | × 0.45359 | 150 lbs = 68.04 kg |
| Grams | Ounces | × 0.03527 | 500 g = 17.6 oz |
| Ounces | Grams | × 28.3495 | 8 oz = 226.8 g |
| Kilograms | Grams | × 1000 | 2.5 kg = 2,500 g |
| Tons (metric) | Kilograms | × 1000 | 1.5 tonnes = 1,500 kg |
| Stone (UK) | Kilograms | × 6.35029 | 10 stone = 63.5 kg |
Body weight reference table (lbs to kg)
| lbs | kg | lbs | kg |
|---|---|---|---|
| 100 lbs | 45.4 kg | 160 lbs | 72.6 kg |
| 120 lbs | 54.4 kg | 180 lbs | 81.6 kg |
| 140 lbs | 63.5 kg | 200 lbs | 90.7 kg |
Temperature Conversions: Celsius, Fahrenheit and Kelvin
Temperature conversions come up constantly when following US recipes (oven temperatures in °F), checking international weather forecasts, or studying chemistry (where Kelvin is standard).
Temperature conversion formulas
Celsius to Fahrenheit: °F = (°C × 9/5) + 32
Fahrenheit to Celsius: °C = (°F − 32) × 5/9
Celsius to Kelvin: K = °C + 273.15
Kelvin to Celsius: °C = K − 273.15Essential temperature reference points
| Celsius (°C) | Fahrenheit (°F) | What It Represents |
|---|---|---|
| −40°C | −40°F | Point where Celsius and Fahrenheit are equal |
| 0°C | 32°F | Water freezing point |
| 20°C | 68°F | Room temperature (comfortable) |
| 37°C | 98.6°F | Normal human body temperature |
| 100°C | 212°F | Water boiling point (sea level) |
| 180°C | 356°F | Moderate oven (baking) |
| 200°C | 392°F | Standard baking temperature |
| 220°C | 428°F | High oven / roasting |
Double the Celsius temperature and add 30. This gives an approximation accurate to within ±2°F for normal weather temperatures. 20°C → 20×2+30 = 70°F (actual: 68°F). Works well for weather, not for precise cooking.
India-Specific Unit Conversions: Area, Gold and Real Estate
India uses several traditional units that are not part of the metric or imperial systems. These are essential for real estate transactions, gold purchases, and land measurement across different states.
Area units (real estate in India)
| Unit | Equivalent | Common Use |
|---|---|---|
| 1 Acre | 4,047 sq m = 43,560 sq ft | Agricultural land across India |
| 1 Bigha (UP) | 2,500 sq m = 27,000 sq ft | North India; varies by state |
| 1 Bigha (Rajasthan) | 1,618 sq m = 17,424 sq ft | Rajasthan land records |
| 1 Kanal | 505.9 sq m = 5,445 sq ft | Punjab, Haryana, HP |
| 1 Guntha | 101.17 sq m = 1,089 sq ft | Maharashtra, Karnataka |
| 1 Marla | 25.3 sq m = 272 sq ft | Punjab, Delhi real estate |
| 1 Cent | 40.47 sq m = 435.6 sq ft | Tamil Nadu, Kerala |
| 1 Hectare | 10,000 sq m = 2.47 acres | Standard metric unit for land |
Gold units (jewellery in India)
| Unit | Grams | Notes |
|---|---|---|
| 1 Tola | 11.664 g | Traditional unit; used for gold pricing on MCX |
| 1 Vori (Bangladesh/WB) | 11.664 g | Same as tola; used in West Bengal |
| 10 grams | 10 g | Standard gold coin (RBI, banks) |
| 1 Sovereign (South India) | 8 g | Standard for jewellery in Tamil Nadu, Kerala |
Volume units (cooking)
| US Measure | Metric | Common in Indian recipes? |
|---|---|---|
| 1 cup | 240 mL | Yes — many modern recipes |
| 1 tablespoon (tbsp) | 15 mL | Yes |
| 1 teaspoon (tsp) | 5 mL | Yes |
| 1 fluid ounce (fl oz) | 29.57 mL | Less common |
How to Use the Tool (Step by Step)
- 1
Open ToolsArena Unit Converter
Navigate to the free unit converter — supports length, weight, temperature, volume, area, and more.
- 2
Select the conversion category
Choose from: Length, Weight, Temperature, Volume, Area, Speed, or Data Size.
- 3
Select your input unit
Choose the unit you are converting from (e.g., metres, kilograms, Celsius).
- 4
Enter your value
Type the number you want to convert. The result updates instantly.
- 5
Read the converted result
The output shows the converted value in your chosen target unit, along with the conversion formula used.
Frequently Asked Questions
How do you convert meters to feet?+−
Multiply metres by 3.28084. Examples: 1 metre = 3.281 feet; 1.75 m = 5.741 feet (approximately 5'9"); 100 metres = 328.1 feet. To convert the other way (feet to metres), multiply by 0.3048.
How do you convert kg to lbs?+−
Multiply kilograms by 2.20462. Examples: 70 kg = 154.3 lbs; 80 kg = 176.4 lbs; 100 kg = 220.5 lbs. To convert lbs to kg, multiply by 0.45359. Quick approximation: multiply kg by 2.2 for lbs (accurate to within 0.2%).
What is the formula for Celsius to Fahrenheit?+−
°F = (°C × 9/5) + 32. Or equivalently, °F = (°C × 1.8) + 32. Examples: 0°C = 32°F (freezing); 100°C = 212°F (boiling); 37°C = 98.6°F (body temperature); 200°C = 392°F (oven temperature). Reverse formula: °C = (°F − 32) × 5/9.
How many feet in a metre?+−
There are 3.28084 feet in 1 metre (exact: 3.280839895...). Common conversions: 1 m = 3.281 ft; 2 m = 6.562 ft; 5 m = 16.404 ft; 10 m = 32.808 ft. The exact definition: 1 foot = 0.3048 metres (exact, by international agreement since 1959).
How many square feet in one acre?+−
There are 43,560 square feet in 1 acre. An acre is also equal to 4,047 square metres, 0.4047 hectares, or a rectangle approximately 66 × 660 feet (1 chain × 1 furlong). In India, 1 acre = 2.47 bigha (varies by state).
What is 1 tola in grams?+−
1 tola = 11.664 grams. The tola is a traditional Indian unit used for weighing gold and silver. It is still quoted in gold market prices on India's commodity exchanges (MCX). 10 tolas = 116.64 grams. A standard RBI gold coin weighs 10 grams = 0.857 tola.
How do I convert miles to kilometres?+−
Multiply miles by 1.60934. Examples: 1 mile = 1.609 km; 10 miles = 16.09 km; 26.2 miles (marathon) = 42.19 km. To convert km to miles, multiply by 0.62137. Quick mental approximation: multiply miles by 1.6 (overestimates by 0.4%).
Convert Any Unit — Free, Instant, No Signup
Length, weight, temperature, volume, area, speed and more. Supports metric, imperial, and India-specific units including acres, tola, bigha, and more.
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