How to use this converter

Three inputs, one result. Here’s each piece:

Category tabs run across the top of the tool: Length, Area, Volume, Weight, Speed, Temp, Time, Pressure, Energy, Power, Frequency, Force, and more. Scroll right to see all 24. Click the one you need and the FROM and TO dropdowns repopulate with every unit in that category.

Value is the number you’re converting. Type it in the left field. The result updates in real time as you type. Decimals and large numbers both work.

FROM is your source unit. Select it from the dropdown. The list is alphabetical within each category.

TO is your target unit. Select it from the second dropdown. The double-arrow button between FROM and TO swaps them instantly so you can reverse the conversion without re-entering anything.

The Result panel (blue) shows 3 things: the converted value in large text, the plain-English equivalence (“1 Nanometer = 0.001 Micrometer”), and the conversion factor (× 0.001) so you can do the math yourself if needed.

Below the result, the Visual Comparison section renders 2 proportional bars, one for each unit. For most conversions the bar widths are proportional to the relative size of the units. This makes it immediately clear which unit is larger and by roughly how much.

All equivalent units is a collapsible section below the visual comparison. Expand it to see your input value converted to every unit in the category simultaneously. Useful when you’re not sure which unit the other person is expecting.

All 24 categories at a glance

Each colour group is loosely themed: blue for everyday physical measurements (length, area, volume, weight, speed, temperature), green for science and engineering (time, pressure, energy, power, frequency, force), orange for data and electrical (density, fuel, data, transfer, current, voltage), and purple for specialist use (resistance, flow, typography, cooking, angle, torque).

What the visual comparison actually shows

Below the result, the tool renders 2 horizontal bars labelled with your input and output values. Here’s what they’re doing.

Example A: 1 kilometer = 1,000 meters (same physical length, different unit name) 1 Kilometer 1,000 Meters Both bars full width: the values are the same physical quantity, just expressed differently.

Example B: 1 nanometer vs 0.001 micrometer (small vs smaller representation) 1 Nanometer 0.001 Micrometer (half width = the result is half the input in numeric value)

The bars show relative numeric magnitude, not absolute physical size. When the result is a much smaller number than the input (like converting 1 nanometer to 0.001 micrometers), the second bar is shorter. When they’re the same physical quantity just renamed (1 km = 1,000 m), both bars fill their container because 1 and 1,000 are being scaled within the same visual range.

It’s a quick gut check: does the converted number feel right relative to what you entered?

The conversion formula

All unit conversions run through one of 2 approaches depending on the category.

For most categories (length, weight, area, pressure, etc.), conversion uses a multiplicative factor:

The conversion factor is specific to each unit pair. The tool displays it below the result as ”× 0.001 (factor)”. For 1 nanometer to micrometers, the factor is 0.001 because 1 nm = 0.001 µm. For micrometers to nanometers, the factor flips to 1,000.

Temperature is the exception. Celsius, Fahrenheit, and Kelvin don’t share a common zero point, so multiplication alone doesn’t work. The formulas are:

Everything else: multiply by the factor. The factor is always visible in the result panel so you can sanity-check or reproduce the calculation yourself.

Quick reference: the conversions people actually need

Length

From	To	Factor
1 inch	25.4 mm	× 25.4
1 foot	0.3048 m	× 0.3048
1 mile	1.60934 km	× 1.60934
1 nautical mile	1.852 km	× 1.852
1 nanometer	0.001 µm	× 0.001
1 micrometer	1,000 nm	× 1,000

Weight

From	To	Factor
1 kg	2.20462 lb	× 2.20462
1 lb	0.453592 kg	× 0.453592
1 oz	28.3495 g	× 28.3495
1 metric ton	1,000 kg	× 1,000
1 stone	6.35029 kg	× 6.35029

Pressure

From	To	Factor
1 atm	101,325 Pa	× 101,325
1 bar	14.5038 psi	× 14.5038
1 psi	6,894.76 Pa	× 6,894.76
1 mmHg	133.322 Pa	× 133.322
1 kPa	0.145038 psi	× 0.145038

Temperature

From	To	Formula
°C	°F	× 9/5, then +32
°F	°C	-32, then × 5/9
°C	K	+ 273.15
K	°C	- 273.15

Data

From	To	Factor
1 byte	8 bits	× 8
1 kilobyte	1,024 bytes	× 1,024
1 megabyte	1,024 KB	× 1,024
1 gigabyte	1,024 MB	× 1,024
1 terabyte	1,024 GB	× 1,024

Real-world examples by profession

Engineering and construction

An American engineer is reviewing a European structural drawing. All dimensions are in millimetres and load specs in kPa. They need imperial equivalents fast.

Healthcare and clinical

A nurse is reviewing a patient’s blood pressure in mmHg and needs to cross-reference with a monitor that reads in kPa.

Aviation

A pilot flying a US aircraft in European airspace needs to convert altimeter settings.

Data and IT

A network engineer needs to estimate how long a 50 GB file transfer will take over a 100 Mbps connection.

Common mistakes people make

Confusing mass and weight units. Kilograms measure mass. Newtons measure force (weight). On Earth, 1 kg of mass exerts about 9.81 N of force due to gravity. The converter handles both through the Weight and Force categories, but they’re measuring different things. When someone says “convert kg to lbs”, they usually mean mass. When a spec sheet says “load in Newtons”, that’s force. Don’t mix them.

Using decimal comma vs decimal point. Some countries write 1,5 to mean one and a half. The converter expects 1.5 with a decimal point. If you enter 1,5 it may interpret it as 15 or throw an error depending on browser locale.

Kilobytes vs kibibytes. In computing, “kilobyte” is ambiguous. Technically 1 KB = 1,000 bytes (SI definition) but historically 1 KB = 1,024 bytes (binary). The converter uses the binary definition (1,024) for data units, which matches how operating systems report file sizes. If you’re working with network speeds (which use the SI definition), results may differ slightly from what the tool shows.

Fuel economy direction. L/100km and mpg are inversely related. Better fuel economy is a lower L/100km but a higher mpg. Doubling L/100km doesn’t halve mpg linearly. The converter handles this correctly, but don’t try to apply a simple ratio mentally.

Gauge vs absolute pressure. Tire pressure is gauge pressure (pressure above atmospheric). The converter converts between absolute pressure units. If your tire says 32 psi, that’s gauge pressure. Adding 14.696 psi (1 atm) gives the absolute pressure. The tool doesn’t add atmospheric pressure for you; it just converts the number you enter.

Why unit systems differ and why it matters

The world runs on 2 measurement systems that barely talk to each other. The metric system (SI) is the standard in science, medicine, and most countries. The imperial system persists in the United States for everyday use and in some industries globally (aviation uses feet for altitude, knots for speed, and inches of mercury for pressure worldwide, regardless of country).

Neither system is going away. Engineers at global companies translate between them constantly. Pharmaceutical dosing uses metric universally. Construction in the US uses feet and inches. Food labelling in the UK uses both. Semiconductor dimensions are in nanometres everywhere. Weather in the US is in Fahrenheit; everywhere else, Celsius.

The practical implication: knowing which system you’re working in, and which the other party expects, prevents errors that cost money and sometimes lives. NASA lost the Mars Climate Orbiter in 1999 because one engineering team used metric and another used imperial, and nobody caught the discrepancy until the spacecraft was destroyed entering the Martian atmosphere.

Unit errors don't just cause confusion. They cause crashes, dosing errors, structural failures, and multimillion-dollar losses. The conversion itself is trivial. Knowing which conversion is needed is the skill.

Specialist categories worth knowing about

Most people use converters for length, weight, and temperature. The specialist categories in this tool are worth knowing exist.

Typography: converts between points (pt), pixels (px), ems, rems, and centimetres. Essential for web and print designers who switch between screen-based specs (px) and print specs (pt or mm). 1 point = 1/72 inch = 1.333 px at 96 DPI.

Torque: covers Newton-metres, pound-feet, kilogram-metres, and others. Used constantly in automotive repair and mechanical engineering. Torque specs in service manuals are often in N·m in Europe and lb·ft in the US. Getting this wrong when tightening cylinder head bolts causes engine damage.

Flow: converts volumetric flow rates (m³/s, litres per minute, gallons per hour, cubic feet per minute). Used in HVAC, plumbing, and industrial process engineering. HVAC contractors switching between US and metric specs need this regularly.

Fuel economy: mpg and L/100km are inversely related and the conversion is non-obvious. 30 mpg = 7.84 L/100km. 50 mpg = 4.70 L/100km. The relationship isn’t linear, so you can’t just scale one to get the other.

Angle: degrees to radians is the one that trips up programmers. Most programming languages expect angles in radians. Most humans think in degrees. 180° = π radians. The converter does this cleanly.

What to do with the result

Copy it: the Copy button in the result panel copies the converted value to your clipboard. No need to manually select the number.

Reverse it: hit the double-arrow swap button to flip the conversion direction. If you just converted 25°C to Fahrenheit and now need to go the other way, one click.

See all equivalents: expand “All equivalent units” to get the full list. If you’re not sure whether someone wants metres, centimetres, or millimetres, show them all three.

Use the factor: the factor shown in the result panel (”× 0.001”) lets you do bulk mental conversion without the tool. Converting 15 nanometres to micrometres? 15 × 0.001 = 0.015 µm. The factor stays constant for any value in the same unit pair.

The bottom line

Unit conversion is infrastructure. You don’t think about it until you need it, and then you need it immediately and correctly.

This tool covers the 24 categories that come up in real work: the everyday ones (length, weight, temperature) and the specialist ones (torque, flow, typography, fuel economy) that only a dedicated unit converter handles well. The “All equivalent units” expansion and the conversion factor display are the two features most converters skip that this one gets right.

Pick your category, enter your value, and read the result. The factor is right there if you want to verify it yourself.