Unit Converter

Convert length, weight, temperature, and 5 more unit types

FreeNo signupRuns in your browser

ToolUnit Converter

From

1mm =0.000001km

All Length Units

Unit	Symbol	Value
Millimeter	mm	1
Centimeter	cm	0.1
Meter	m	0.001
Kilometer	km	0.000001
Inch	in	0.03937007874
Foot	ft	0.003280839895
Yard	yd	0.001093613298
Mile	mi	6.213711922e-7
Nautical Mile	nmi	5.399568035e-7

Pairs with

Starter kits

Need productivity templates?

Task trackers, project planners, and automation scripts that save hours every week. Starting at $4.

Browse Productivity Kits

About Unit Converter

Unit conversion is a daily requirement across science, engineering, cooking, fitness, travel, and commerce. The metric and imperial systems are not simply scaled versions of each other — they have different base units, different subdivisions, and different conventions for specific domains like data storage (SI vs. binary prefixes) and temperature (which requires an offset, not just a multiplier). Having all categories in one place eliminates the need to context-switch between multiple specialized calculators.

How it works

Each unit category uses a single canonical base unit as the intermediate step. For length, the base unit is meters. To convert miles to feet, for example, the tool first converts miles to meters (× 1609.344), then meters to feet (× 3.28084). This two-step canonical approach means only N conversion factors need to be stored for N units in a category (one per unit to/from base), rather than N² factors for all possible pairs.

Temperature is the exception — it uses direct formula pairs rather than a base unit approach, because temperature offsets make the canonical method produce incorrect results for non-zero conversions.

Bidirectional conversion means editing either input field recalculates the other. The full conversion table below the main converter shows the entered value converted to all other units in the category simultaneously, useful for quick multi-unit reference.

Who this is for

A recipe developer converting an American recipe's measurements (cups, ounces, Fahrenheit) to metric (ml, grams, Celsius) for a European audience.

A software engineer checking whether a server's 512 GiB RAM specification equals 549.8 GB in the SI units their monitoring dashboard reports.

A cyclist training for a European race converting their usual 25 miles per hour pace to kilometers per hour to understand how it compares to the race's posted speed segments.

An engineering student converting a force expressed in pounds-force to Newtons for a physics problem set that requires SI units.

A traveler checking the weather forecast in Fahrenheit from a US weather app and converting to Celsius to compare with local expectations.

Scope note: Currency conversion is not included — exchange rates are dynamic and require a live API. Specialized scientific units (moles, candela, pascals) are not covered in the current version. Data storage conversion uses standard SI decimal prefixes for KB/MB/GB and binary IEC prefixes for KiB/MiB/GiB — verify which system your context uses before converting.

How to use it

1
Select a unit category from the tabs (Length, Weight, Temperature, etc.)
2
Enter a value in either input field
3
Select the units to convert from and to
4
See the result instantly — conversion is bidirectional
5
View the full conversion table for all units in that category

Frequently asked questions

How many unit types are supported?

8 categories: Length, Weight, Temperature, Area, Volume, Speed, Data storage, and Time — covering over 60 individual units.

Does it handle temperature conversions correctly?

Yes — temperature uses the correct formulas (not just multiplication). Celsius, Fahrenheit, Kelvin, and Rankine are all supported.

Can I convert between metric and imperial?

Yes — all unit categories include both metric and imperial units side by side.

Is any data sent to a server?

No. All conversions happen in your browser with no network requests.

How do temperature conversions work — why are they different from other units?

Most unit conversions are linear (multiply by a constant). Temperature conversions involve a shift (offset) as well as a scale. Celsius to Fahrenheit: °F = (°C × 9/5) + 32. Celsius to Kelvin: K = °C + 273.15. Kelvin to Rankine: °R = K × 9/5. Using a simple multiplier for temperature would give wrong results — the tool applies the correct two-step formula for each conversion pair.

How is data storage converted — is 1 KB = 1000 bytes or 1024 bytes?

The SI definition (used by hard drive manufacturers and internet speeds): 1 KB = 1000 bytes, 1 MB = 1,000,000 bytes. The binary definition (used by operating systems for RAM and file sizes): 1 KiB = 1024 bytes, 1 MiB = 1,048,576 bytes. This converter supports both systems — select KB/MB/GB for decimal and KiB/MiB/GiB for binary.

What is the most common conversion error people make?

Confusing imperial weight (pounds, ounces) with troy weight (used for precious metals). One troy ounce = 31.1035 grams while one avoirdupois ounce = 28.3495 grams — a 10% difference. When converting gold, silver, or gemstone weights, always clarify which ounce system applies. This converter uses standard avoirdupois for general weight.