Free Unit Converter
Updated September 2026
Convert between units of length, weight, temperature, volume, speed, area, and data — select a category, enter a value, choose units, and get the converted result instantly.
Verified Capabilities
Instantly converts across Length, Weight, Temperature, Volume, Speed, Area, and Data in one interface.
Entering one value shows it converted to every unit in that category at once, not just a single target unit.
Uses exact defined constants (e.g. 1 inch = 25.4mm exactly), accurate to at least 6 significant figures.
The Data tab uses binary prefixes (1 GB = 1024 MB), matching how operating systems display file sizes — not the decimal GB (1000 MB) used on some spec sheets. Expect a small mismatch if comparing against those.
Whether you're planning finances, comparing options, or verifying numbers, having an accurate calculator ready saves time and prevents costly mistakes.
Convert between units of length, weight, temperature, volume, speed, area, and data — select a category, enter a value, choose units, and get the converted result instantly. Results are immediate — no waiting, no loading screens, no account required.
Who uses the Unit Converter?
- Students converting between metric and imperial units for science homework or coursework
- Cooks adapting recipes from US cups and tablespoons to metric grams and millilitres
- Travellers quickly converting miles per hour to kilometres per hour on road signs abroad
Common uses and search terms
The Unit Converter is frequently used for: unit converter, metric, imperial, measurement, length converter, weight converter, temperature converter, unit conversion, online unit converter. Whether you need a quick result or are working through a longer project, the tool handles all common variations without any configuration.
Accuracy and formula transparency
The Unit Converter uses a validated formula consistent with published standards from recognised financial and mathematical authorities. All arithmetic is performed with 64-bit IEEE 754 floating-point precision — the same standard used by Microsoft Excel, Google Sheets, and professional financial software. Rounding, if applied, follows standard half-up convention unless stated otherwise. Inputs and results are processed entirely in your browser; no data is transmitted to any server. For consequential financial or legal decisions, always verify results with a qualified professional.
Why use Allio Tools's Unit Converter?
Everything runs locally in your browser. No data is sent to a server, logged, or stored anywhere. The tool is completely free with no usage limits, no premium tiers, and no account required. Available in 11 languages and optimised for all screen sizes, the Unit Converter works on desktop, tablet, and mobile with no app download needed.
See also:Mortgage Calculator · Currency Converter · Loan Calculator
How the Unit Converter works
Click the category tab at the top: Length, Weight, Temperature, Volume, Speed, Area, or Data.
Enter a value in the input field for the unit you're converting from.
Select the From and To units from the dropdowns.
The converted result appears immediately — no button press needed.
Tips & tricks
- The Data tab uses binary prefixes (1 GB = 1,024 MB), matching how Windows and macOS report file sizes — if you're cross-checking against a spec sheet that uses decimal GB (1,000 MB), expect a small mismatch; that's the manufacturer's convention, not an error here.
- US and UK gallons differ (1 US gallon ≈ 0.833 UK gallons) — if a recipe or fuel figure looks off by about 20%, check which gallon the source actually meant before assuming the conversion is wrong.
- For cooking conversions, remember that volume-to-weight (e.g. cups to grams) varies by ingredient density — a cup of flour and a cup of sugar don't weigh the same, so this converter's volume units are for liquid/volume measures, not a universal ingredient substitute.
- Entering a value converts it to every unit in that category at once (e.g. one length input shows km, miles, feet, inches, cm, mm, and yards simultaneously) — useful for comparing several unit systems side by side rather than picking one target unit at a time.
Popular Conversions
Length
Weight
Temperature
Volume
Speed
Area
Data
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Click the Temperature tab, enter your Celsius value in the input field, set From to Celsius and To to Fahrenheit. The formula is °F = (°C × 9/5) + 32. For quick reference: 0°C = 32°F, 20°C = 68°F, 100°C = 212°F.
Can I convert between metric and imperial units?
Yes. All tabs support conversion between metric (SI) and imperial/US units. For length: metres to feet, kilometres to miles, centimetres to inches. For weight: kilograms to pounds, grams to ounces. For volume: litres to gallons (US or UK).
How do I convert between gigabytes and megabytes?
Click the Data tab, enter the value, and select GB to MB (or any other data unit pair). The converter uses binary prefixes (1 GB = 1,024 MB) for storage units, which matches how operating systems report file and drive sizes.
Does the converter handle very small or very large numbers?
Yes. The calculator handles both scientific notation inputs and standard decimal values. Results for very large or small conversions are shown in standard decimal notation; for extreme values, scientific notation may appear automatically.
How accurate are the conversion factors?
All conversion factors are based on exact international definitions (e.g. 1 inch = 25.4 mm exactly, 1 mile = 1,609.344 m exactly). Temperature conversions use the full formula. Results are accurate to at least 6 significant figures for all supported units.
What types of units can I convert with the Unit Converter?
The Unit Converter covers 7 unit categories: Length, Weight, Temperature, Volume, Speed, Area, Data. You can convert in both directions — for example cm to m; kg to grams — with instant results and no sign-up required.
Is my data safe when using the Unit Converter?
Completely safe. The Unit Converter processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.
How accurate are the Unit Converter results?
The Unit Converter uses standard, well-established mathematical formulas used by professionals worldwide — the same ones used by banks, financial advisors, and accounting software. Results are as accurate as the inputs you provide. See our <a href="/methodology/">Methodology page</a> for formula sources and references. For financial decisions, always verify with a qualified professional.
Can I share the Unit Converter results with someone?
Yes. Copy the result number or screenshot the page to share via message, email, or social media. You can also bookmark and share the tool URL directly — the Unit Converter opens instantly for anyone with a modern browser, no account needed.
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