Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin instantly in your browser.
- Free, no account
- No watermark
- No usage limit
About the Temperature Converter
Most temperature converters make you pick a "from" scale, pick a "to" scale, then hit convert to get one number back, which is a click too many when you usually want all three scales in front of you anyway. Half the time you don't even know which scale you want until the number is in front of you, so this one skips the back and forth: type a value, tell it which scale that number is already in, and Celsius, Fahrenheit, and Kelvin all show up together, updating live as you type, with no convert button to press. Nothing you type leaves your device, and once the page has loaded it keeps working with no connection.
You run into this more than you'd think. A recipe written in Celsius when your oven dial reads Fahrenheit. A holiday forecast that says 35 and you're honestly not sure whether that means shorts or a heat warning. A fever chart printed for another country. Same snag every time, the number means nothing until it's sitting on your scale.
Two small things make it quicker to actually use. Every row has a copy button, so you grab just the value you need. And the "Copy shareable link" button builds a URL with your number and scale already baked in, so you can text someone "180 C, here's what that is" as a link they can open and poke at themselves.
How to use
- Type your temperature in the Value box. Positive, negative, decimals like 98.6, all fine.
- In the From dropdown, pick the scale that number is already in (Celsius, Fahrenheit, or Kelvin).
- Read the answer in the table underneath. All three scales sit there at once and they update the moment you type, so there is nothing to press.
- Hit the copy button on any row to grab that one value, or "Copy shareable link" to hand the whole conversion to someone else.
That is the entire thing. No sign-up, no result buried under ads, nothing stored.
Converting a change is not the same as converting a reading
To convert a temperature reading takes two steps, you scale the degree size and you shift the starting point. Celsius to Fahrenheit is x1.8 then +32. A temperature change works differently. It only scales the degree size without shifting the starting point, so the +32 has to go.
That means a 5 degree Celsius rise is a 9 degree Fahrenheit rise, not 41. The climate target everyone quotes, 1.5 C of warming, is 2.7 F of warming, not the 34.7 you would get by running it through the full formula. The reason is simple, when you subtract two readings the +32 appears in both and cancels itself out, leaving only the x1.8.
It reads like a technicality right up until a news graphic converts "2 degrees of warming" as if it were a thermometer reading and prints a number that is flatly wrong. So if you are ever converting a gap, a rise, a drop, anything that is a difference rather than an actual reading, use the 1.8 factor on its own and leave the 32 out.
A few numbers beat the formula for everyday stuff
For weather you don't really need the math at all. Learn five or six anchor points and you'll read any forecast in your head:
- 0 C = 32 F, water freezes
- 20 C = 68 F, comfortable room
- 30 C = 86 F, properly hot
- 37 C = 98.6 F, body temperature
- 100 C = 212 F, water boils
And one oddity worth keeping around: -40 C and -40 F are the exact same temperature. It is the single point where the two scales cross, so it's an easy one to memorize alongside the anchor points above.
There is a rough shortcut too. Double the Celsius and add 30. Take 16 C, double it to 32, add 30, you land on 62 F. The real answer is 60.8, close enough to decide on a jacket. Just don't lean on it for an oven or a fever. At baking temperatures the trick can be dozens of degrees off, and a degree or two on a fever reading is the whole question, so those are exactly the moments you want the exact converter instead of a party trick.
Frequently asked questions
How do I convert Celsius to Fahrenheit, and the other way?
Celsius to Fahrenheit: multiply by 1.8 (that is 9/5) and add 32, so 25 C becomes 45 + 32 = 77 F. Going back, subtract 32 first and then multiply by 5/9, so 98.6 F becomes (98.6 - 32) = 66.6, then x 5/9 = 37 C. The order is what people get wrong on the return trip, you have to subtract before you multiply, never the reverse. The tool does both directions the instant you type, but the formula is handy for a rough check in your head.
What is Kelvin and why is there no negative Kelvin?
Kelvin is the scale science runs on, the SI unit for temperature. It uses the same size step as Celsius but starts at absolute zero, the coldest anything can physically get, which is -273.15 C. Because it begins right at the bottom it never goes negative, and you write it with no degree sign, 300 K, not 300 degrees. Convert by adding 273.15 to a Celsius value, or subtracting to come back. It shows up outside the lab too, the "color temperature" of a light bulb is Kelvin, which is why a warm bulb reads 2700 K and a cold daylight one reads 5000 K or higher.
Is normal body temperature really 98.6 F?
That figure is a 19th-century average and it runs a touch high. Modern studies put the typical baseline closer to 97.9 F, around 36.6 C, and your own reading drifts through the day, lower in the morning and higher in the evening. So a thermometer showing 98.0 is sitting well inside the normal range rather than signalling a fever. The usual medical line for an actual fever is 38.0 C, which comes out to 100.4 F.
What oven temperature is 180 C, and what about a fan oven?
180 C works out to 356 F, which is why metric recipes and US recipes line up at roughly "180 C / 350 F", the 6 degree gap being smaller than most home ovens are accurate to anyway. If you have a fan or convection oven, the common advice is to knock about 20 C (call it 25 F) off whatever a conventional recipe states, because the moving air cooks faster.
Can I convert negative temperatures, and does -40 really match?
Yes to both. Celsius and Fahrenheit run well below zero and the converter handles them without a problem, including the -40 point where the two scales show the identical number. Kelvin is the one exception, it cannot go negative, so a Celsius value under -273.15 produces a Kelvin figure below zero that has no physical meaning even though the arithmetic still hands you one.
How many decimals does it show, and is that precise enough?
It trims to a clean number of significant figures and drops trailing zeros, so a whole-number answer reads as a whole number instead of 20.00000. That is far more precision than cooking, weather, or a fever check will ever want. For a lab measurement where the last decimal matters, work the exact formula on your precise input rather than reading it off a rounded display.
Does it work offline and stay private?
Both, yes. Every conversion happens right in your browser with no server involved, so it keeps going even if your connection drops after the page has loaded. Nothing you type is transmitted or saved, your numbers stay on your own device.