Boiling point, both ways
The default conversion, applying the full formula.
Input
100 °C → °FOutput
212 °F (100 × 9/5 + 32) — and 373.15 K alongsideTemperature Converter
Convert Celsius, Fahrenheit, and Kelvin with the real offset formulas, precision control, and a reference table from absolute zero to oven heat.
- Free public tool
- No sign-up for this tool
- Processing clearly labeled
- Instant results
Content last reviewed
From
To
100.00°C equals
212.00°F
Decimals
All three scales
Common reference points
| Reference | °C | °F | K |
|---|---|---|---|
| Absolute zero | -273.15 | -459.7 | 0 |
| Water freezes | 0 | 32.0 | 273.15 |
| Cold day | 10 | 50.0 | 283.15 |
| Room temperature | 21 | 69.8 | 294.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Hot summer day | 40 | 104.0 | 313.15 |
| Water boils | 100 | 212.0 | 373.15 |
| Oven (baking) | 180 | 356.0 | 453.15 |
The formulas
- °F = (°C × 9/5) + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
The scales cross at −40°: −40°C is exactly −40°F. Kelvin starts at absolute zero (−273.15°C), the coldest anything can get, and has no negative values.
Quick Start
Enter the temperature
Type the value — negatives and decimals included.
Pick the two scales
Choose From and To among Celsius, Fahrenheit, and Kelvin, with a swap button.
Read all three
The headline result converts your pair, and every scale is shown alongside.
Examples
Body temperature
The number every parent has converted at 2am.
Input
98.6 °F → °COutput
37 °C ((98.6 − 32) × 5/9)About the Temperature Converter
Temperature is the conversion you cannot do with a multiplier: 0 °C is 32 °F, not 0 °F, because the scales start from different zeros. That offset is why weather reports, oven settings, and lab values need the full formula — and why this converter exists as its own tool rather than a row in a generic one.
Enter a temperature, pick any pair among Celsius, Fahrenheit, and Kelvin, and the conversion applies the real math: °F = °C × 9/5 + 32, K = °C + 273.15, with everything pivoting through Celsius so all three scales stay mutually consistent. A swap button flips the direction, precision control rounds from whole degrees to six decimals (with scientific notation for extremes), and the result copies in one click.
A built-in reference table anchors intuition with the temperatures people actually reason from: absolute zero (−273.15 °C), water freezing (0 °C / 32 °F) and boiling (100 °C / 212 °F), room temperature (21 °C), body temperature (37 °C / 98.6 °F), a hot summer day, and a baking oven (180 °C / 356 °F). Between the formulas and the anchors, the converter doubles as the mental model — the two-minute read that finally makes Fahrenheit weather reports parse.
How to Use Temperature Converter
Type the temperature into the amount box — negative values and decimals are fine.
Pick the From and To scales: Celsius, Fahrenheit, or Kelvin. The swap button reverses the pair.
Read the headline result, with all three scales shown together below it.
Set the decimals (default 2, from 0 to 6, plus scientific notation) and copy the result.
Use the reference table — freezing, room, body, boiling, oven — to sanity-check that a converted value lands where intuition says it should.
Key Features
All three scales
Celsius, Fahrenheit, and Kelvin, converted with the exact offset formulas rather than approximations.
Every scale at once
The value renders in all three scales simultaneously, so no second conversion is ever needed.
Reference anchors
A table of meaningful temperatures — absolute zero to oven heat — for instant sanity checks.
Precision control
0–6 decimals with a scientific-notation toggle; results copy as plain numbers.
When to Use Temperature Converter
Weather across systems
Parse a Fahrenheit forecast (or explain a Celsius one) while travelling or reading foreign news.
Cooking and baking
Convert oven temperatures between recipe conventions — 350 °F is the classic 177 °C.
Science homework
Move between Celsius and Kelvin with the exact 273.15 offset shown.
Product specs
Check operating-temperature ranges quoted in the other scale.
How It Works
Temperature scales are affine, not proportional — they differ by both a scale factor and an offset — so conversion needs the full formulas rather than a single multiplier. The converter pivots through Celsius: the input is first converted to Celsius (°C = (°F − 32) × 5/9 from Fahrenheit, °C = K − 273.15 from Kelvin), then from Celsius to the target (°F = °C × 9/5 + 32, K = °C + 273.15).
The pivot guarantees the three displayed scales always describe the same physical temperature. Kelvin's role is worth a sentence: it is Celsius shifted so zero sits at absolute zero — the coldest possible temperature — which is why Kelvin values are never negative and why science prefers the scale.
Supported Formats and Options
Options
From / To scales with swap
Any pair of °C, °F, and K, reversible in one click.
Decimals and notation
0–6 decimal places (default 2) and a scientific-notation toggle.
Copy and reset
Copy the result as a plain number; reset restores the 100 °C → °F default.
Common Errors and Troubleshooting
Common errors
Doubling °C and adding 30
The street shortcut (°C × 2 + 30) is fine near room temperature but drifts elsewhere — 100 °C would come out as 230 °F instead of 212. Use the exact formula for anything that goes in an oven or a report.
Treating temperature differences like temperatures
A change of 10 °C is a change of 18 °F — the offset does not apply to differences, only to absolute readings. Converting a "rise of 10 degrees" through the full formula overstates it.
Negative Kelvin
If a conversion yields negative Kelvin, the input was below absolute zero — physically impossible, so check for a typo or a mixed-up scale.
Troubleshooting guide
Getting temperatures right in practice
- Oven conversions: recipes round — 350 °F is exactly 176.7 °C, baked as 175 or 180. Convert exactly, then round to the nearest oven mark.
- Fan ovens: conversion is not the only adjustment; fan-assisted ovens typically run recipes about 20 °C lower than conventional settings. That is oven lore, not conversion math.
- Quick intuition: memorize the anchors — 0 °C/32 °F freezing, 21 °C/70 °F room, 37 °C/98.6 °F body, 100 °C/212 °F boiling — and most conversions become sanity checks.
- Lab work: use the Kelvin pair and full decimals; the 273.15 offset is exact by definition.
Limitations and Important Notes
The converter covers the three scales in general use — Rankine, Réaumur, and other historical scales are out of scope. It converts absolute temperatures, not temperature differences (which use only the 9/5 factor, without the offset). Inputs below absolute zero convert arithmetically but describe nothing physical; the reference table flags where the floor is.
Privacy and Data Processing
Conversion is local arithmetic in your browser — values are never uploaded or stored.
Tips and Best Practices
Practical tips
Use the exact formula for cooking and science; save the ×2+30 shortcut for small talk.
Convert temperature differences with the 9/5 factor only — the +32 offset applies to readings, not changes.
Anchor on the reference table values to catch scale mix-ups instantly.
Round oven temperatures to the nearest mark after converting exactly.
Remember Kelvin has no degree sign and no negative values.
Best practices
Thinking in two scales
Build the anchor ladder once: freezing 0/32, cool day 10/50, room 21/70, body 37/98.6, boiling 100/212. With five rungs memorized, any converted value can be sanity-checked by where it falls between rungs — which catches the swapped-scale errors no formula can.
For recipes and specs, convert at the source and write the converted value next to the original. A cookbook annotated once never needs converting again, and a spec sheet with both scales survives being read by either audience.
Technical Details
Conversions pivot through Celsius with the exact affine formulas (°F = °C × 9/5 + 32; K = °C + 273.15). Display precision defaults to 2 decimals, adjustable 0–6 with a scientific-notation toggle; copy payloads are unformatted numbers. Input accepts any finite number, including negatives. Fully client-side.
Comparison
Anchor temperatures across the scales
| Reference | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 21 | 69.8 | 294.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils | 100 | 212 | 373.15 |
| Baking oven | 180 | 356 | 453.15 |
Who Is This For?
Travellers and expats parsing the other system's weather, cooks converting oven settings, students moving between Celsius and Kelvin, and anyone reading spec sheets across markets. The reference table makes it useful even when you do not have a number to convert — as the cheat sheet itself.
Frequently Asked Questions
What is the Celsius to Fahrenheit formula?
°F = °C × 9/5 + 32, and back the other way °C = (°F − 32) × 5/9. The offset exists because the scales define zero differently — 0 °C is water's freezing point, while 0 °F is much colder.
Why do the scales cross at −40?
Because −40 × 9/5 + 32 = −40: the one temperature where Celsius and Fahrenheit agree. It falls out of the two lines intersecting — a classic check that a converter's math is right.
What is Kelvin and why does science use it?
Celsius shifted so zero sits at absolute zero (−273.15 °C), the coldest possible temperature. With no negative values and degrees the same size as Celsius, it makes physical equations cleaner — hence its role as the SI unit.
How do I convert a temperature difference?
Use only the scale factor: a change of X °C is a change of X × 9/5 °F, with no +32. The offset belongs to absolute readings — applying it to differences is a common and sneaky error.
Is the quick ×2+30 rule good enough?
For conversation about the weather, roughly — it is within a couple of degrees between about 0 and 30 °C. For cooking, science, or anything written down, use the exact result; the shortcut is 18 degrees wrong at boiling point.