Unit Converter

Last updated: Jul 22, 2026 | Reviewed by Calkulator Team | 2 min read

Conversion

Convert between any measurement units — length, weight, temperature, and more

From kilometres to miles, kilograms to pounds, Celsius to Fahrenheit — covering 10 categories with precise formulas. Essential for travel, cooking, science homework, and international product specifications.

For quick mental conversion: multiply km by 0.6 for miles, multiply kg by 2.2 for pounds.

Conversion Settings

Conversion Formula

Select category and units to see formula.

Result

—

Quick Reference — Common Conversions

Live Result Illustration

Visual summary — updates instantly as you enter values above

LIVE

Real-Life Guide to Using the Unit Converter

Length, mass, temp, speed, area. Use the examples and checks below to turn the number into a practical decision.

When this calculator is useful

Reach for this when a recipe, product spec, or import invoice lists measurements in a unit you don't think in — say a US recipe in cups and ounces, or a machine part spec in inches — and you need it in metric (or vice versa) before you can actually use it.

For most people, the best way to use the Unit Converter is to try the real case first, then change one input at a time. That makes the trade-off visible. For example, with a loan calculator you can change tenure while keeping the same rate; with an investment calculator you can change return assumption while keeping the same monthly contribution; with a health, education or measurement calculator you can check how much one input changes the final category.

The result should answer a practical question: Can I afford this? How much should I save? Is this score enough? Is this measurement within range? What is the safer or cheaper option? If the output does not answer the decision clearly, adjust the inputs until the scenario matches your real situation.

Real-Life Example

Converting a US recipe to metric: Priya finds a US baking blog recipe that calls for 2 cups of flour and needs grams for her Indian kitchen scale.

12 cups of all-purpose flour ≈ 240 grams (using the standard 120 g per cup for flour, not the water-volume 236 mL per cup, since flour density differs from water).

2Now change one input, such as rate, time, quantity, unit or score, and compare the new result with the first one.

Volume-to-weight conversions depend on the ingredient's density, so a generic cup-to-mL converter alone can give the wrong gram figure for baking.

Practical Advice

Use the Unit Converter as a planning tool, not just a number generator. Write down the inputs you used, because the final answer is meaningful only when you remember the assumptions behind it.

If the decision affects money, health, tax, safety, academics or legal compliance, keep a second check ready. That second check may be a bank quote, payslip, official rule, prescription, site measurement, mark sheet or invoice.

Common Mistakes

Rounding mid-calculation — converting 5.5 inches to 13.97 cm, rounding to 14 cm, then using that 14 cm for a further conversion instead of the original precise value, which compounds error.
Confusing mass and weight units — treating 1 kg and 1 kgf (kilogram-force) as interchangeable when doing engineering or force calculations, when only mass converts directly.
Mixing up US and UK definitions of the same word — a US gallon (3.785 L) is not a UK/imperial gallon (4.546 L), a roughly 20% difference that trips up people converting fuel efficiency figures.
Applying a linear conversion formula to temperature — trying to convert a 10°C temperature *difference* to Fahrenheit by multiplying by 1.8 and adding 32 (that +32 only applies to absolute readings, not deltas).
Forgetting that area and volume don't scale linearly — assuming doubling a length unit doubles the area, when 1 square metre is not 2× a half-square-metre-equivalent length conversion; area scales by the square and volume by the cube of the linear factor.

How to Interpret Results

The converted figure is only as precise as the input you typed, so if your source number was itself rounded (e.g. "about 6 feet"), don't treat the output's extra decimal places as exact; carry 2-3 significant figures for everyday use and more only for technical work.

A good interpretation looks at both the main result and the supporting values. If a page shows totals, ratios, categories, schedules or warnings, read those together instead of focusing only on the biggest number.

Unit Converter FAQs

Useful answers for interpreting the output, avoiding mistakes and using the result responsibly.

Can one tool really convert length, mass, temperature, speed, and area accurately?

Yes — length, mass, speed, and area all use fixed multiplicative conversion factors (e.g. 1 inch = 2.54 cm exactly), so a single calculator can apply the correct factor per category. Temperature is the exception since it needs an offset, not just multiplication, which is why it's handled with its own formula internally.

Why does 1 mile not convert to a clean round number of kilometres?

1 mile equals exactly 1.609344 km because the mile and kilometre were defined independently by different historical systems (imperial vs metric) and only later reconciled with an exact conversion factor. There's no rounding error — that's genuinely the precise ratio.

Is a US ton the same as a metric tonne?

No. A US (short) ton is 907.18 kg, a UK (long) ton is 1,016.05 kg, and a metric tonne is exactly 1,000 kg. Always check which "ton" a foreign document means before converting, especially for shipping or commodity weights.

How does the calculator handle square and cubic units like square feet to square metres?

It squares (or cubes) the linear conversion factor rather than applying it once — so square feet to square metres uses (0.3048)² = 0.0929, not 0.3048 directly. This is the step people most often get wrong when doing it by hand for a room or plot area.

Why do my manually calculated results differ slightly from the calculator?

Manual calculations often use rounded conversion factors (like 2.5 instead of 2.54 for inches to cm), while the calculator uses the full precision figure. Over multiple steps this difference compounds, so for anything technical, always convert from the original source number rather than a pre-rounded intermediate.

Does this calculator match the units used on Indian land and property documents?

Indian property listings often use bigha, gaj, or acre alongside square feet and square metres, and these vary by state (a bigha in Punjab differs from one in Uttar Pradesh). This calculator covers the standard international units; for state-specific land units, cross-check with your local registrar's conversion table.

What's the difference between converting speed in km/h to m/s versus mph?

km/h to m/s divides by 3.6 (since 1 km = 1000 m and 1 hour = 3600 s), while km/h to mph multiplies by roughly 0.6214. These are unrelated conversion chains, so don't assume a shortcut between m/s and mph without going through a proper factor.

What should I do if my converted number looks obviously wrong?

First check you selected the correct "from" and "to" units, not swapped ones — this is the single most common input error. Then sanity-check with a rough mental estimate (e.g. 1 kg is a bit over 2 lbs) before trusting a precise-looking decimal output.

What is a Unit Converter?

A unit converter translates values between different measurement systems — from metric to imperial and vice versa. It covers all everyday measurement categories: length (km to miles), weight (kg to lbs), temperature (�C to �F), area, volume, speed, data storage, pressure, and energy.

Unit conversion is essential for international travel, scientific calculations, engineering, cooking recipes, and understanding foreign product specifications. All conversions use precise mathematical formulas to ensure accuracy across all supported units.

Example Conversions

Scenario: Mr. Rohit, recently returned NRI from USA — needs to convert his apartment dimensions from feet/miles to metric for Indian builders: room is 12ft�10ft, house is 1,500 sq.ft, his commute was 8.5 miles, he weighs 180 lbs, oven set at 375�F

1�F = (�C — 9/5) + 32 = (100 — 1.8) + 32 = 212�F

Length: 5 km to miles

21 km = 0.621371 miles → 5 km = 3.107 miles

Weight: 70 kg to pounds

31 kg = 2.20462 lbs → 70 kg = 154.32 lbs

✓ All categories converted instantly

How to Use the Unit Converter

Select the Category — choose from Length, Weight, Temperature, Area, Volume, Speed, Time, Data Storage, Pressure, or Energy.
Enter the Value to Convert — type the number you want to convert; decimals are supported for precise measurements.
Select the From Unit — the unit your value is currently expressed in (e.g., kilometres, Celsius, kilograms).
Select the To Unit — the unit you want to convert to; use Swap Units to instantly reverse the direction without re-entering data.
Click "Convert" — the result appears with the formula used; the Quick Reference table shows common conversions in that category for context.

Benefits

Covers 10 categories and 100+ units in a single tool — no need for separate length, weight, or temperature converters
Displays the conversion formula used — learn the relationship while getting your result
Quick Reference table shows common conversions in the selected category for instant comparison
Swap Units button reverses conversion instantly — no need to re-enter the value
Supports precise scientific units (Pascal, Joule, Kelvin) alongside everyday units (kg, km, �C)

Key Terms

SI (Metric) System: Globally adopted system — metre, kilogram, second, kelvin as base units; used in science, medicine, and most countries including India
Imperial System: Inch, foot, mile, pound, Fahrenheit — used primarily in the USA; also historically used in India for land (feet, acres) and body weight (pounds)
Conversion Factor: The number a value must be multiplied by to convert between two units (e.g., 1 km — 0.621371 = miles)
Absolute Temperature (Kelvin): Scale starting from absolute zero (0 K = -273.15�C); used in thermodynamics and gas law calculations — no negative values possible
Binary vs SI Data Units: 1 KB (SI) = 1,000 bytes; 1 KiB (binary) = 1,024 bytes — OS storage displays differ from manufacturer labels because of this distinction

Frequently Asked Questions

How do I convert temperature between Celsius, Fahrenheit, and Kelvin?

�C to �F: multiply by 9/5 then add 32. Example: 100�C = (100 — 1.8) + 32 = 212�F. �F to �C: subtract 32 then multiply by 5/9. Example: 98.6�F = (98.6 - 32) — 5/9 = 37�C (normal body temperature). �C to Kelvin: add 273.15. Example: 0�C = 273.15 K (water's freezing point). Temperature conversions involve addition/subtraction unlike length or weight which use only multiplication — this is why you can't simply apply a single factor. The converter handles all three directions automatically.

What are the most common unit conversions for everyday use in India?

Frequent conversions: 1 km = 0.621 miles (for international navigation apps); 1 kg = 2.205 lbs (travel luggage limits and fitness apps); 1 inch = 2.54 cm (clothing sizes, monitor screen sizes, pipe diameters); 1 litre = 0.264 US gallons (fuel economy comparisons with US cars); 1 acre = 4,047 m� (land measurement); �C → �F (following US or UK recipes). Indian cooking often requires ml → cups (1 cup = 240 ml). For property: 1 sq ft = 0.0929 m�; 1 cent = 435.6 sq ft (common in South India).

Why does my 1 TB hard drive show less than 1,000 GB in Windows?

Hard drive manufacturers use the decimal SI definition: 1 TB = 1,000 GB = 1,000,000 MB = 1,000,000,000 KB. Operating systems traditionally used binary units: 1 GiB = 1,024 MiB. So a "1 TB" (1,000,000,000,000 bytes) drive — 1,0244 = approximately 909 GiB, which older Windows showed as "909 GB." Modern Windows 11 and macOS now report in decimal GB, reducing this confusion. When comparing storage specs, check whether the value uses base-10 (manufacturer) or base-2 (OS) measurement.

How do I convert between land area units used in Indian property transactions?

Common Indian land units: 1 acre = 43,560 sq ft = 4,047 m�; 1 guntha = 1,089 sq ft (1/40 acre); 1 cent = 435.6 sq ft (1/100 acre, common in South India); 1 bigha varies by state (e.g., UP: 2,508 m�; West Bengal: 1,337 m�; Rajasthan: 1,618 m�). For legal and registration documents, always use square metres or square feet (specified in the document) to avoid ambiguity. Traditional units like bigha differ significantly between states and are not standardised at the national level.

What pressure units does this converter support and which should I use for tyre pressure?

Supported units include Pascal (Pa), kilopascal (kPa), bar, millibar (mbar), atmosphere (atm), PSI (pounds per square inch), and mmHg. For vehicle tyres in India: car tyres typically require 30�35 PSI (�2.0�2.4 bar); motorcycle front tyres 28�32 PSI (�1.9�2.2 bar), rear 36�42 PSI (�2.5�2.9 bar). Petrol station gauges in India may show PSI or kPa — 1 PSI = 6.895 kPa. For blood pressure, mmHg is standard (120/80 mmHg normal); no conversion needed for clinical use.