How big is an acre, and how does it compare to a hectare?

1 acre is exactly 43,560 square feet, or about 4,046.86 square meters. A hectare (the metric land unit) is 10,000 m², which is about 2.471 acres. So a 5-acre lot is about 20,234 m², or roughly 2 hectares. This is the most common land-measurement conversion in US real estate.

Unit Converter | Length, Weight, Temperature, Area, Volume, Speed

Convert length, weight, temperature, area, volume, and speed instantly. Inches ↔ cm, pounds ↔ kg, °F ↔ °C, acres ↔ m², gallons ↔ liters, mph ↔ km/h and more — US customary and metric units are equally easy to reach, with a live table of every unit in the category.

Value

Enter the number you want to convert (use a period for decimals: 12.5).

From

Popular conversions

Result precision

Decimal places Thousands separator (1,000)

2.54 cm1 inch

0.454 kg1 pound

37°C98.6°F (body temp)

3.785 L1 gallon (US)

ℹ️ Note: This converter applies International System of Units (SI) constants directly (e.g. 1 inch = 2.54 cm exactly, 1 pound = 0.45359237 kg, 1 nautical mile = 1,852 m). It uses US customary definitions throughout: 1 acre = 4,046.8564224 m², 1 gallon = the US gallon (3.785411784 L — not the UK imperial gallon, 4.54609 L), and 1 ton = the US short ton (907.18474 kg — not the metric tonne or UK long ton). The "Result precision" setting lets you choose the number of decimal places (0–10) and toggle the thousands separator. Results are for informational purposes; confirm the official/local definition for critical or legal measurements.

How does unit conversion work?

The logic behind length, weight, area, volume, and speed conversion, why temperature is different, and the most-searched US ↔ metric conversions.

Unit conversion means expressing the same measurement in a different unit. For linear quantities (length, weight, area, volume, speed) conversion is a single multiplication: the value is converted to a shared base unit (meter, kilogram, etc.), then converted into the target unit. Temperature is not linear — because its zero point shifts between scales, it needs its own formula instead of a plain multiplier. This tool applies both correctly across all six categories, with US customary units always one tap away from their metric counterparts.

US customary units you will use every day

Quick answerThe US customary conversions people look up most: 1 in = 2.54 cm, 1 ft = 30.48 cm, 1 mi = 1.609 km, 1 lb = 0.4536 kg, 1 oz = 28.35 g, 1 gal (US) = 3.785 L, 1 acre = 4,046.86 m². These come up constantly for height, body weight, road distances, fuel, and land size — every one of them is a source or target option in the tool above, not an afterthought.

Height & length: in → cm (×2.54), ft → m (×0.3048), mi → km (×1.609344)
Weight: lb → kg (×0.453592), oz → g (×28.3495)
Volume: gal (US) → L (×3.785412), cup → mL (×236.588)

How do you convert length units? (inches, feet, miles, meters)

Quick answer1 in = 2.54 cm, 1 ft = 12 in = 0.3048 m, 1 yd = 3 ft = 0.9144 m, 1 mi = 1,609.344 m ≈ 1.609 km, 1 nautical mile = 1,852 m. Metric units step by powers of 10 (mm → cm → m → km); the US ↔ metric conversion always uses a fixed multiplier (e.g. ×2.54 for inches).

How do you convert temperature? (Fahrenheit, Celsius, Kelvin)

Quick answerTemperature is offset, so a simple multiplier is not enough: °C = (°F − 32) × 5/9, °F = °C × 9/5 + 32, K = °C + 273.15. For example, 100°F = 37.8°C; 98.6°F (normal body temperature) = 37°C; 0°C = 32°F = 273.15 K. Interestingly, −40°C and −40°F are the exact same temperature.

That is why the answer to "how many °F is 1°C worth?" is not a simple ratio — it is the full formula's result (1°C = 33.8°F). The tool shows the exact formula used under the result whenever you convert a temperature.

Area units: acres, hectares, and square feet

Quick answer1 acre = 43,560 ft² ≈ 4,046.86 m², 1 hectare = 10,000 m² ≈ 2.471 acres, 1 ft² = 0.0929 m², 1 mi² = 640 acres. Acres and square feet dominate US real estate and land listings, while hectares and square meters are the metric standard almost everywhere else — this is the single most common pair to convert between the two systems.

Volume & kitchen measurements: cups, quarts, and gallons

Quick answerUS kitchen and fuel volumes nest neatly: 1 cup = 8 fl oz, 1 pint = 2 cups, 1 quart = 2 pints, 1 gallon = 4 quarts = 16 cups. In metric terms, 1 cup ≈ 236.6 mL and 1 gallon ≈ 3.785 L. Recipes, gas tanks, and paint cans are the most common places this conversion comes up.

Most-searched conversions (ready reference)

The everyday US ↔ metric conversions people look up most. Use the calculator above for your own exact value.

Popular unit conversions (SI & US customary constants)
Conversion	Category	Result
1 in → cm	Length	2.54 cm
1 ft → cm	Length	30.48 cm
1 mi → km	Length	1.609 km
1 lb → kg	Weight	0.4536 kg
1 kg → lb	Weight	2.2046 lb
98.6°F → °C	Temperature	37°C
1 acre → m²	Area	4,046.86 m²
1 gal (US) → L	Volume	3.785 L
60 mph → km/h	Speed	96.56 km/h
100 km/h → mph	Speed	62.14 mph
1 cup → mL	Volume	236.59 mL
1 hectare → acre	Area	2.471 acre

Popular calculations

Related quick converters: height, weight & temperature

The three conversions people need most in everyday life, one tap away: ft/in ↔ cm height, lb ↔ kg weight, and °F ↔ °C temperature.

📐Height: ft/in → cm

Convert your height in feet and inches to centimeters and meters (e.g. 5 ft 9 in).

Feet (ft)

Inches (in)

🏋️Weight: lb → kg

Convert pounds (lb) to kilograms and grams. Handy for fitness and shipping.

Pounds (lb)

🌡️Temperature: °F → °C

Convert Fahrenheit to Celsius and Kelvin (oven, weather, recipes).

Fahrenheit (°F)

👶Weight: lb + oz → kg

Convert a compound pounds-and-ounces weight (e.g. baby weight, package weight) to kilograms and grams.

Pounds (lb)

Ounces (oz)

2026 unit conversion tables

Category-by-category conversion factors and quick equivalents, with US customary units listed first. All based on international SI definitions.

Length — meter equivalent per unit
Unit	Meter equivalent	Practical
1 inch (in)	0.0254 m	2.54 cm
1 foot (ft)	0.3048 m	12 in
1 yard (yd)	0.9144 m	3 ft
1 mile (mi)	1,609.344 m	1.609 km
1 nautical mile (nmi)	1,852 m	1.852 km
1 millimeter (mm)	0.001 m	0.1 cm
1 centimeter (cm)	0.01 m	10 mm
1 meter (m)	1 m	3.281 ft
1 kilometer (km)	1,000 m	0.621 mi

Weight — kilogram equivalent per unit
Unit	Kilogram equivalent	Practical
1 pound (lb)	0.453592 kg	16 oz
1 ounce (oz)	0.0283495 kg	28.35 g
1 ton (US, short)	907.185 kg	2,000 lb
1 milligram (mg)	0.000001 kg	0.001 g
1 gram (g)	0.001 kg	1,000 mg
1 kilogram (kg)	1 kg	2.2046 lb
1 tonne (metric)	1,000 kg	2,204.6 lb
1 troy ounce	0.0311035 kg	31.10 g
1 carat	0.0002 kg	200 mg

Temperature — Fahrenheit, Celsius, Kelvin equivalents
Fahrenheit (°F)	Celsius (°C)	Kelvin (K)
−40°F	−40°C	233.15 K
32°F (freezing)	0°C	273.15 K
98.6°F (body temp)	37°C	310.15 K
212°F (boiling)	100°C	373.15 K
350°F (oven)	176.7°C	449.85 K

°C = (°F − 32) × 5/9 · °F = °C × 9/5 + 32 · K = °C + 273.15

Area — square meter equivalent per unit
Unit	Square meter equivalent	Practical
1 square inch (in²)	0.00064516 m²	6.4516 cm²
1 square foot (ft²)	0.092903 m²	144 in²
1 square yard (yd²)	0.836127 m²	9 ft²
1 acre	4,046.86 m²	43,560 ft²
1 square mile (mi²)	2,589,988 m²	640 acres
1 square mm (mm²)	0.000001 m²	0.01 cm²
1 square cm (cm²)	0.0001 m²	100 mm²
1 square meter (m²)	1 m²	10.764 ft²
1 hectare (ha)	10,000 m²	2.471 acres
1 square km (km²)	1,000,000 m²	247.1 acres

Volume — US customary and metric equivalents
Unit	Liter equivalent	Practical
1 teaspoon (tsp, US)	0.004929 L	4.93 mL
1 tablespoon (tbsp, US)	0.014787 L	3 tsp
1 fluid ounce (fl oz, US)	0.029574 L	2 tbsp
1 cup (US)	0.236588 L	8 fl oz
1 pint (US)	0.473176 L	2 cups
1 quart (US)	0.946353 L	2 pints
1 gallon (US)	3.785412 L	4 quarts
1 milliliter (mL)	0.001 L	0.001 L
1 liter (L)	1 L	0.264 gal
1 cubic meter (m³)	1,000 L	264.17 gal

Speed — meters/second equivalent per unit
Unit	m/s equivalent	Practical
1 mile/hour (mph)	0.44704 m/s	1.609 km/h
1 foot/second (ft/s)	0.3048 m/s	0.682 mph
1 knot (nmi/h)	0.514444 m/s	1.151 mph
1 kilometer/hour (km/h)	0.277778 m/s	0.621 mph
1 meter/second (m/s)	1 m/s	2.237 mph

Time — second equivalent per unit
Unit	Second equivalent	Practical
1 second (s)	1 s	1,000 ms
1 minute (min)	60 s	60 s
1 hour (hr)	3,600 s	60 min
1 day	86,400 s	24 hr
1 week	604,800 s	7 days
1 year (365 days)	31,536,000 s	52.14 weeks

Data storage — byte equivalent per unit (decimal, base 1000)
Unit	Byte equivalent	Practical
1 byte (B)	1 B	8 bits
1 kilobyte (KB)	1,000 B	10³ B
1 megabyte (MB)	1,000,000 B	10⁶ B
1 gigabyte (GB)	1,000,000,000 B	10⁹ B
1 terabyte (TB)	1,000,000,000,000 B	10¹² B
1 kibibyte (KiB)	1,024 B	2¹⁰ B
1 mebibyte (MiB)	1,048,576 B	2²⁰ B
1 gibibyte (GiB)	1,073,741,824 B	2³⁰ B
1 tebibyte (TiB)	1,099,511,627,776 B	2⁴⁰ B

Decimal units (KB/MB/GB/TB, base 1000) are what storage manufacturers and most file managers show. Binary units (KiB/MiB/GiB/TiB, base 1024) are what some operating systems use for memory and disk usage — that's why a "1 TB" drive can show up as about 931 GiB.

Pressure — pascal equivalent per unit
Unit	Pascal equivalent	Practical
1 psi (lbf/in²)	6,894.76 Pa	0.0689 bar
1 bar	100,000 Pa	14.5038 psi
1 atmosphere (atm)	101,325 Pa	14.6959 psi
1 kilopascal (kPa)	1,000 Pa	0.145 psi
1 millimeter of mercury (mmHg)	133.322 Pa	0.0193 psi

Energy — joule equivalent per unit
Unit	Joule equivalent	Practical
1 joule (J)	1 J	0.2390 cal
1 calorie (cal)	4.184 J	0.0042 kJ
1 kilowatt-hour (kWh)	3,600,000 J	3.6 MJ
1 BTU	1,055.06 J	0.293 Wh

Power — watt equivalent per unit
Unit	Watt equivalent	Practical
1 watt (W)	1 W	0.001 kW
1 kilowatt (kW)	1,000 W	1.341 hp
1 horsepower (hp, mechanical)	745.7 W	0.7457 kW

Fuel consumption — L/100km equivalent per unit (higher mpg/km-L = more efficient, higher L/100km = less efficient)
Unit	L/100km equivalent (at 30 mpg US)	Practical
1 mile/gallon (mpg, US)	235.215 ÷ mpg	30 mpg (US) ≈ 7.84 L/100km
1 mile/gallon (mpg, UK)	282.481 ÷ mpg	30 mpg (UK) ≈ 9.42 L/100km
1 liter/100km (L/100km)	1 L/100km	7.84 L/100km ≈ 30 mpg (US)
1 kilometer/liter (km/L)	100 ÷ (km/L)	12.75 km/L ≈ 30 mpg (US)

mpg and km/L are inverted relative to L/100km: fuel economy (mpg, km/L) is "distance per unit of fuel," while fuel consumption (L/100km) is "fuel per unit of distance" — that's why the conversion is division, not a simple multiplier. Formula: L/100km = 235.214583 ÷ mpg (US), or 282.480936 ÷ mpg (UK), or 100 ÷ km/L.

Unit conversion glossary

Short definitions of the key terms used in measurement and conversion.

US customary unitsThe measurement system used day-to-day in the United States: inches/feet/miles, pounds/ounces, Fahrenheit, and gallons/cups.

Metric system (SI)The International System of Units, built around meters, kilograms, liters, and Celsius, used almost everywhere outside the US.

Base unitThe unit a category's conversions are calculated through (e.g. meter for length, kilogram for weight).

Conversion factorThe fixed multiplier that turns one unit into the base unit (e.g. 1 inch = 0.0254 m).

OffsetA constant added or subtracted in addition to multiplying, needed for scales like temperature whose zero point shifts (e.g. +32 for Fahrenheit).

Inch & footUS customary length units; 1 inch is exactly 2.54 cm, 1 foot is 12 inches (30.48 cm).

Mile vs. nautical mileA statute mile is 1.609 km; a nautical mile is 1.852 km and is used in aviation and at sea.

AcreA US land-area unit equal to 43,560 square feet, or about 4,046.86 m² — standard in US real estate listings.

HectareA metric land-area unit equal to 10,000 m², or about 2.471 acres.

Gallon (US vs. imperial)The US gallon is 3.785 L; the UK imperial gallon is larger, at 4.546 L. This tool uses the US gallon throughout.

Pound (lb) & ounce (oz)US customary weight: 1 lb = 0.4536 kg = 16 oz; 1 oz = 28.35 g.

Short ton vs. metric tonneA US short ton is 2,000 lb (907.18 kg); a metric tonne is 1,000 kg (2,204.6 lb) — they differ by about 10%.

KnotA nautical speed unit: 1 nautical mile per hour, equal to 1.852 km/h.

Troy ounce & caratPrecious-metal and gem weight units: 1 troy ounce = 31.1035 g (gold/silver); 1 carat = 0.2 g (diamonds/gems).

Decimal vs. binary bytesDecimal KB/MB/GB/TB use base 1000 (as sold by storage makers); binary KiB/MiB/GiB/TiB use base 1024 (as some operating systems report usage) — they differ by about 2-10% depending on the size.

psi vs. bar vs. atmPressure units: 1 psi (pound-force per square inch) = 0.0689 bar; 1 atmosphere (atm, average sea-level air pressure) = 14.696 psi = 1.01325 bar = 101.325 kPa.

Joule, calorie & kWhEnergy units: 1 calorie = 4.184 joules; 1 kilowatt-hour (the unit on electricity bills) = 3,600,000 joules; 1 BTU = 1,055.06 joules.

Watt & horsepowerPower units (rate of energy use): 1 horsepower (mechanical) ≈ 745.7 watts ≈ 0.7457 kilowatts.

mpg (US) vs. mpg (UK)Fuel economy units: the US gallon (3.785 L) and UK/imperial gallon (4.546 L) differ, so 30 mpg (US) ≈ 36 mpg (UK) for the same car — always check which gallon a figure uses.

L/100km vs. mpg/km-LL/100km is "fuel per distance" (lower is better); mpg and km/L are "distance per fuel" (higher is better) — they're inversely related, not linearly proportional.

In-depth guides

Detailed answers to the most commonly asked unit conversion questions.

How many cm is an inch? A practical guide for height and screen sizes

1 inch is exactly 2.54 centimeters. To convert inches to cm, multiply the value by 2.54. For example, a 6.1-inch phone screen measures 6.1 × 2.54 ≈ 15.5 cm diagonally, and a 55-inch TV has a 139.7 cm diagonal. Since 1 foot = 12 inches = 30.48 cm, a height of 5 ft 9 in (69 inches) is about 175.3 cm.

Going the other way, divide by 2.54 to convert cm to inches: 180 cm ≈ 70.9 in ≈ 5 ft 10.9 in. You can do this instantly with the "Height: ft/in → cm" mini tool above, or with the Length tab in the main converter.

Converting Fahrenheit to Celsius: why a simple multiplier is not enough

Fahrenheit and Celsius have both a different step size and a different zero point, so a plain multiplication will not work — an offset is required. Formula: °C = (°F − 32) × 5/9. First subtract 32 (correcting for the zero-point difference), then multiply by 5/9 (correcting for the step-size difference). For example, 100°F: (100 − 32) × 5/9 = 37.8°C.

The reverse direction is °F = °C × 9/5 + 32. 37°C = 37 × 9/5 + 32 = 98.6°F (normal body temperature). Kelvin is found by simply adding 273.15 to Celsius: 25°C = 298.15 K. Interesting fact: −40°C and −40°F are the exact same temperature.

Acres, hectares, and square feet: understanding land measurements

The two units confused most often in US land measurement are the acre and the square foot. 1 acre is exactly 43,560 square feet — so a 5-acre lot is 217,800 ft². 1 hectare is 10,000 m² ≈ 2.471 acres, and 1 square mile = 640 acres. Real estate listings in the US almost always use acres or square feet, while most of the rest of the world uses hectares and square meters.

Use the Area tab above to convert instantly between acres, hectares, square feet, square meters, square miles, and square yards.

Frequently asked questions

How many centimeters are in an inch?

1 inch is exactly 2.54 centimeters. Multiply by 2.54 to convert inches to cm (10 in = 25.4 cm), and divide by 2.54 to convert cm to inches. 1 foot (ft) = 12 inches = 30.48 cm.

How do you convert Fahrenheit to Celsius?

Use °C = (°F − 32) × 5/9; the reverse is °F = °C × 9/5 + 32. For example, 100°F = 37.8°C, 32°F = 0°C, and 98.6°F = 37°C. For Kelvin: K = °C + 273.15.

How many kilometers are in a mile?

1 mile = 1.609344 km (about 1.61 km). Multiply miles by 1.609 to get km. 1 nautical mile = 1.852 km and is used in aviation and at sea. Conversely, 1 km ≈ 0.621 mi.

How do you convert pounds to kilograms?

1 lb = 0.4536 kg; 1 kg = 2.2046 lb. Multiply lb by 0.4536 to get kg, or multiply kg by 2.2046 to get lb. For example, 150 lb ≈ 68 kg, and 70 kg ≈ 154.3 lb. 1 lb = 16 oz = 453.6 g.

How many liters are in a gallon?

1 US gallon = 3.785412 liters; 1 UK (imperial) gallon = 4.54609 liters. In the US, gallon almost always means the US gallon (3.785 L). For example, 10 gallons ≈ 37.85 L. In reverse, 1 liter ≈ 0.264 US gallons.

How big is an acre?

An acre is exactly 43,560 square feet, or about 4,046.86 m². That is roughly the size of a US football field without the end zones. 1 hectare = 10,000 m² ≈ 2.471 acres, and 1 square mile = 640 acres.

What is the difference between a US ton and a metric tonne?

A US (short) ton = 2,000 lb = 907.185 kg. A metric tonne = 1,000 kg ≈ 2,204.6 lb. A UK (long) ton is 2,240 lb (≈1,016 kg). All three are called "ton(ne)" but differ by several percent — check which one applies.

How do you convert km/h to mph?

Multiply km/h by 0.621371 to get mph, or multiply mph by 1.609344 to get km/h. For example, 100 km/h ≈ 62.14 mph, and 60 mph ≈ 96.56 km/h. For nautical speeds, 1 knot = 1.852 km/h = 1.151 mph.

How many cups are in a quart, a pint, or a gallon?

1 cup = 8 fl oz; 1 pint = 2 cups; 1 quart = 2 pints (4 cups); 1 gallon = 4 quarts (16 cups). So a gallon of milk holds 16 cups. This nested 2-2-4 ratio is the easiest way to remember US kitchen volume conversions.

What is the difference between a decimal and a binary gigabyte?

A decimal gigabyte (GB) = 1,000³ bytes (1,000,000,000 B) — this is how storage makers and most software list sizes. A binary gibibyte (GiB) = 1,024³ bytes (1,073,741,824 B) — used by some operating systems for memory/disk usage. The two differ by about 7.4%, so a "1 TB" drive can show as ≈931 GiB.

How do you convert psi to bar or atm?

1 psi = 0.0689476 bar; 1 bar = 14.5038 psi. 1 atm = 14.6959 psi = 1.01325 bar = 101.325 kPa. Tire gauges commonly use psi in the US and bar/kPa elsewhere; 1 mmHg (blood pressure) = 0.019337 psi.

How many joules are in a kilowatt-hour or a calorie?

1 kWh = 3,600,000 J (3.6 MJ) — the unit on electricity bills. 1 calorie = 4.184 J, and 1 BTU = 1,055.06 J. A 100-watt device run for 10 hours uses 1 kWh, about 860 food calories worth of energy.

Is my data or text sent anywhere when I use this tool?

No. Every conversion runs entirely inside your browser using JavaScript. Nothing is uploaded to a server, stored, or shared — only when you tap Share or Copy link is the calculation optionally encoded into that link.

Methodology & sources

ToolPico's Unit Converter is a free, independent tool. In linear categories (length, weight, area, volume, speed), every value is first converted to the category's base unit, then converted to the target unit; the constants used are international SI definitions (e.g. 1 inch = 0.0254 m, 1 lb = 0.45359237 kg, 1 nautical mile = 1,852 m, 1 acre = 4,046.8564224 m², 1 US gallon = 3.785411784 L). Temperature is offset-based and uses dedicated formulas: °C = (°F − 32) × 5/9, °F = °C × 9/5 + 32, K = °C + 273.15.

Assumptions: weight uses the US short ton (907.18474 kg), not the metric tonne (1,000 kg) or UK long ton (1,016.0469 kg); volume uses US customary units (fl oz, cup, pint, quart, gallon = 3.785411784 L), not the UK imperial gallon (4.54609 L); area includes both acres (4,046.8564224 m²) and hectares (10,000 m²); precious-metal weight uses troy ounce (31.1034768 g) and metric carat (0.2 g). The optional precision setting only affects display formatting — internal calculations always use full floating-point values. Sources: SI unit definitions · NIST/BIPM conversion constants · the international inch/pound (avoirdupois) agreement. Last updated: July 21, 2026. Results are for informational purposes only; confirm the official, legal, or local definition for critical measurements.

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Unit Converter

How does unit conversion work?

US customary units you will use every day

How do you convert length units? (inches, feet, miles, meters)

How do you convert temperature? (Fahrenheit, Celsius, Kelvin)

Area units: acres, hectares, and square feet

Volume & kitchen measurements: cups, quarts, and gallons

Most-searched conversions (ready reference)

Popular calculations

Related quick converters: height, weight & temperature

2026 unit conversion tables

Unit conversion glossary

In-depth guides

Frequently asked questions

Methodology & sources

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