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Unit Converter
Convert between 100+ units across length, weight, temperature, area, volume, speed, data, time, pressure, and energy.
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1 mm = 0.1 cm
🔒 All calculations happen in your browser. Nothing is sent anywhere.
What is the best free unit converter online?
OptiPix Unit Converter handles 100+ units across length, weight, temperature, volume, speed, and data storage with instant, offline-capable conversion in your browser. Unlike UnitConverters.net, it is ad-free and works without any network connection once loaded.
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<iframe src="https://optipix.art/embed/unit-converter" width="100%" height="600" style="border:1px solid #e4e4e7;border-radius:8px;" title="Unit Converter by OptiPix" loading="lazy"></iframe> <p style="font-size:12px">Free tool by <a href="https://optipix.art/unit-converter">OptiPix Unit Converter</a></p>
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About Unit Converter
Last updated: May 2026
OptiPix Unit Converter handles conversions across 10 categories with over 100 units. Convert length (mm to miles), weight (grams to pounds), temperature (Celsius to Fahrenheit to Kelvin), area, volume, speed, digital data (KB to TB, binary and decimal), time, pressure, and energy. Two-way live conversion updates as you type. Each conversion shows the formula used. Quick-swap button to reverse from/to units. All calculations use pure JavaScript arithmetic with no external dependencies or network calls.
How It Works
Each unit stores a conversion factor relative to a base unit in its category (e.g., meters for length). To convert, the tool multiplies the input by the source factor and divides by the target factor. Temperature uses special formulas since it's not a simple ratio.
Use Cases
- •Convert between metric and imperial measurements
- •Calculate temperature conversions for cooking or weather
- •Convert digital storage units for file management
- •Convert time zones and duration units
- •Calculate area and volume for construction projects
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OptiPix Unit Converter vs unitconverters.net vs Google unit converter vs ConvertUnits
| Feature | OptiPix | unitconverters.net | Google unit converter | ConvertUnits |
|---|---|---|---|---|
| Runs fully locally/offline | Yes | No | No | No |
| Categories | Length, weight, temp, volume, area, speed, data, more | Comprehensive | Common units | Comprehensive |
| Precision control | Yes | Fixed | Fixed | Fixed |
| Ads | None | Heavy | None | Heavy |
| Live conversion as you type | Yes | Yes | Yes | Yes |
Competitor details reflect publicly listed free-tier features and may change.
Conversion accuracy notes
All conversions route through SI base units with exact legally-defined factors: the international inch is exactly 25.4mm, the pound exactly 453.59237g, and the US gallon exactly 3.785411784L. Routing through a canonical base unit avoids the compounding rounding errors chained pairwise tables accumulate.
Temperature is handled as the affine transformation it is (offset plus scale, since 0°C is 32°F) rather than a simple ratio - the error every naive 'multiply by factor' implementation makes. Data units distinguish decimal (MB, 10^6) from binary (MiB, 2^20) prefixes explicitly, the source of the 'missing' gigabytes on every hard drive.
Results render with significant-figure awareness so 1 inch shows as exactly 2.54cm rather than 2.5400000000000005 - the floating-point artifact you'll see in quickly-built converters.
Frequently Asked Questions
What categories of units are supported?
How does temperature conversion work?
Does it support binary data units?
Can I swap the from and to units?
Is any data sent to a server?
Why does my hard drive show less space than advertised?
Is a US gallon the same as a UK gallon?
How do I convert Celsius to Fahrenheit in my head?
How do I convert inches to centimeters?
How do I convert kilograms to pounds?
What is the formula to convert Celsius to Fahrenheit?
How many MB are in a GB?
Is there a unit converter that works offline?
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