Is this unit converter free?

Yes, completely free — no account, no subscription, no hidden fees.

Do you upload my data to a server?

No. All conversions run entirely in your browser using JavaScript. Nothing is sent to any server.

Does it work offline?

Yes. Once the page is loaded, you can disconnect from the internet and all conversions continue to work.

How do I convert Fahrenheit to Celsius online?

Select the Temperature category, choose Fahrenheit (°F) as the source unit, enter your value, and select Celsius (°C) as the target — the result and formula appear instantly.

Which unit categories are supported?

Length, Weight, Temperature, Area, Volume, Speed, Data, Pressure, Time, and Torque — covering more than 90 individual units from metric, imperial, digital, and traditional East Asian measurement systems. Common pairs such as centimeters to inches, millimeters to inches, and lbs to kg live in the Length and Weight categories.

Why is temperature handled separately from other units?

Because temperature scales do not share a zero point. Metres and feet are related by a single multiplication, so ten metres is exactly twice five metres. Celsius and Fahrenheit are related by a multiplication and an offset, so 20 °C is not twice 10 °C in any meaningful sense. The converter routes temperature through its own path so the offset is never dropped.

Why do repeated conversions drift by a tiny amount?

Converting there and back can leave you a fraction off the number you started with. That is ordinary binary floating-point rounding, the same effect that makes 0.1 plus 0.2 come out slightly past 0.3 in almost every programming language. The error is far below any practical measurement precision, but it is why the last displayed digit can move.

📏 Unit Converter – Instant, Free & Offline

This free unit converter instantly converts length, weight, temperature, area, volume, speed, data, pressure, time, and torque units — entirely in your browser with no upload and no login required.

A unit converter changes a measurement from one unit to another, such as length, weight, temperature, area, volume or speed.

Value

Unit

Result

Unit

Private by design. This tool runs entirely in your browser — nothing you enter is uploaded or stored, and it works offline.

About

Toolio's Unit Converter covers 10 categories and more than 90 units — from millimeters to nautical miles, milligrams to carats, Celsius to Kelvin, hectares to acres, milliliters to tablespoons, knots to Mach, bits to petabytes, pascals to psi, milliseconds to years, and newton-metres to pound-feet. It shows the conversion formula for every calculation so you can understand exactly how the result is derived. Because everything runs client-side, your inputs never leave your device — making it safe to use on sensitive or offline environments.

How to use

Select a category (Length, Weight, Temperature, Area, Volume, Speed, Data, Pressure, Time, or Torque).
Choose the source unit from the left dropdown.
Type your value into the input field — the result updates instantly.
Choose the target unit from the right dropdown to see the converted value.
Hit the swap button (⇄) to reverse the conversion, or click Copy to copy the result.

FAQ

Is this unit converter free?: Yes, completely free — no account, no subscription, no hidden fees.
Do you upload my data to a server?: No. All conversions run entirely in your browser using JavaScript. Nothing is sent to any server.
Does it work offline?: Yes. Once the page is loaded, you can disconnect from the internet and all conversions continue to work.
How do I convert Fahrenheit to Celsius online?: Select the Temperature category, choose Fahrenheit (°F) as the source unit, enter your value, and select Celsius (°C) as the target — the result and formula appear instantly.
Which unit categories are supported?: Length, Weight, Temperature, Area, Volume, Speed, Data, Pressure, Time, and Torque — covering more than 90 individual units from metric, imperial, digital, and traditional East Asian measurement systems. Common pairs such as centimeters to inches, millimeters to inches, and lbs to kg live in the Length and Weight categories.
Why is temperature handled separately from other units?: Because temperature scales do not share a zero point. Metres and feet are related by a single multiplication, so ten metres is exactly twice five metres. Celsius and Fahrenheit are related by a multiplication and an offset, so 20 °C is not twice 10 °C in any meaningful sense. The converter routes temperature through its own path so the offset is never dropped.
Why do repeated conversions drift by a tiny amount?: Converting there and back can leave you a fraction off the number you started with. That is ordinary binary floating-point rounding, the same effect that makes 0.1 plus 0.2 come out slightly past 0.3 in almost every programming language. The error is far below any practical measurement precision, but it is why the last displayed digit can move.