Free Temperature Converter - Celsius, Fahrenheit, Kelvin Online Calculator

A Double the Celsius number and add 30. For 20°C, that gives 70°F — pretty close to the real 68°F. This trick works best between 10°C and 30°C. For precise cooking or science, always use our converter to avoid off results.

A They're the same thing — centigrade was the original name, but it got renamed to Celsius in 1948 to honor Anders Celsius. You'll still see 'centigrade' on some older thermometers or cookbooks. Our converter treats them identically. So if a vintage French cookbook says '200° centigrade,' that's 200°C, which equals 392°F and 473.15K. No extra steps needed.

A Because -40 is the magic number where the two scales cross. At -40°C, the Fahrenheit reading is also -40°F. It's the only temperature where Celsius and Fahrenheit match exactly. Below that, Fahrenheit numbers get lower faster. Above it, Celsius climbs faster. This quirk happens because the scales have different zero points and step sizes. So if you're checking a deep freeze or a Siberian weather report, -40 means the same thing on both.

A At sea level, water boils at 100°C — that's textbook. But climb to 2,000 meters and your '100°C' water might be bubbling at 93°C. Air pressure drops as you go up, so water needs less heat to boil. Your thermometer still shows 100°C, but the actual temperature is lower. This kills pasta-cooking times and changes brewing chemistry. Use our converter to check altitude-adjusted boiling points before you cook at elevation.

A When a US news report warns of a 95°F heatwave, you might not realize that's 35°C — dangerous territory. Our converter bridges that gap fast. Just type in their Fahrenheit number and see the Celsius equivalent instantly. For example, 100°F equals 37.8°C, which is when heat exhaustion becomes a real risk. Keep our tool bookmarked when traveling or reading international weather alerts.

A No, and here's the catch. When a recipe says 100°C, it's talking about Celsius, not the 100K you'd see in a physics lab. In Kelvin, 100K is actually -173.15°C — deep cryogenic territory. Our converter handles both, so if you're following a modernist cooking guide that lists temperatures in Kelvin, type 373.15K to see it's 100°C. That's the boiling point. For kitchen use, stick with Celsius or Fahrenheit, but it's good to know the tool won't trip you up if a science-based recipe throws Kelvin at you.

A It's true, not a rumor. At -40, both scales intersect because of how their zero points and step sizes were set. You'll see it in places like Fairbanks, Alaska, or a Winnipeg winter. Type -40 into our converter and both boxes will show -40. That's the only value where they match. Below that, Fahrenheit drops faster than Celsius. Above, it climbs faster. Handy party fact, but also practical if you're checking extreme cold warnings. Don't trust your gut at those temps — let the tool confirm.

A Trust the recipe's Celsius values, because they reflect the author's actual testing. Most European recipes list Celsius, and US ovens show Fahrenheit. For example, a cake baking at 180°C needs 356°F on your dial. Many US ovens round to 350°F, which works fine. But if you're making something precise like custard, the extra 6°F matters. Enter your recipe's Celsius number into our converter and set your oven to the exact Fahrenheit equivalent. Your baking will come out consistent every single time.

A Gas expansion relies on absolute zero. If you calculate volume at 0°C (273.15K) and double the temperature, you use 546.30K, not 0°C. Using Celsius directly breaks thermodynamics math. Our converter handles those awkward decimals instantly so your technical report won't fail peer review.

A Gas marks puzzle plenty of home cooks trying out vintage British baking books. A gas mark of 4 translates to 177 degrees Celsius or 350 degrees Fahrenheit. Our tool doesn't track old gas marks directly, but you can plug those converted numbers straight into your modern dial. Type the Celsius figure to match your fan oven easily.