What is 100°C in Fahrenheit?

100 °C equals 212 °F — that is the boiling point of water at sea level. The formula is F = C × 9/5 + 32, so 100 × 9/5 = 180, plus 32 = 212. Going the other way, water freezes at 0 °C = 32 °F. Those two fixed points, 32 and 212, are exactly 180 °F apart over the same range that Celsius covers in 100 degrees, which is where the 9/5 ratio comes from.

How do I convert body temperature 37°C to Fahrenheit?

Normal body temperature 37 °C is 98.6 °F. Plug it into F = C × 9/5 + 32: 37 × 9/5 = 66.6, plus 32 = 98.6 °F. A fever of 38 °C is 100.4 °F, and 40 °C is 104 °F. The old 98.6 °F figure comes straight from rounding 37 °C, which is why it looks suspiciously precise — the real average runs a touch lower, around 36.6 °C (97.9 °F).

What are the formulas for converting between Celsius, Fahrenheit and Kelvin?

From Celsius: F = C × 9/5 + 32, K = C + 273.15, R = (C + 273.15) × 9/5. Reversing them: C = (F − 32) × 5/9, C = K − 273.15. Example: 25 °C → 25 × 9/5 + 32 = 77 °F, and 25 + 273.15 = 298.15 K. Kelvin and Celsius share the same degree size, so you only add or subtract 273.15; Fahrenheit and Rankine share the smaller degree, related by the same 9/5 factor.

Why does Kelvin have no degree symbol?

Kelvin is an absolute thermodynamic scale where 0 K is absolute zero, the point where molecular motion stops, so a kelvin is a unit of temperature itself rather than a 'degree' on an arbitrary scale. Since 1968 the SI convention writes 300 K, not 300 °K. Water freezes at 273.15 K and boils at 373.15 K — a 100 K span identical in size to 100 °C, because the kelvin and the Celsius degree are defined to be equal.

Why are -40°C and -40°F the same temperature?

−40 is the one value where the Celsius and Fahrenheit scales cross. Set C = F in F = C × 9/5 + 32: x = x × 9/5 + 32, so x − 1.8x = 32, −0.8x = 32, x = −40. Below that, Fahrenheit numbers sit above Celsius (−50 °C = −58 °F); above it the gap reopens the usual way (0 °C = 32 °F). It is a handy sanity check: any converter that does not return −40 °F for −40 °C has a bug.

Read a US weather forecast in Celsius

You are traveling to the States and the app says it will be 95 °F tomorrow. Type 95 °F and read 35 °C — genuinely hot, pack accordingly. A forecast low of 41 °F is 5 °C, jacket weather. The four-scale readout means you never have to remember which direction the 9/5 goes; you just type the number you see and read the one you think in.

Follow an American recipe with a metric oven

A cookie recipe says bake at 350 °F but your oven dial is in Celsius. Type 350 °F and read 176.67 °C — set the dial to 175 or 180. Roasting at 425 °F is 218 °C, and a low-and-slow 225 °F is 107 °C. Pair this with the cooking unit converter when the same recipe also lists cups and sticks of butter.

Check a physics or chemistry homework answer

A problem gives a gas at 27 °C and asks for kelvin. Type 27 °C and read 300.15 K, with the formula K = C + 273.15 shown so you can see exactly why. Absolute-zero questions (−273.15 °C = 0 K) and the Rankine scale used in some engineering courses are all on the same screen, and anything below absolute zero is flagged as impossible.

Convert lab or industrial setpoints across scales

An autoclave datasheet specs 121 °C, a US-built furnace controller reads in Fahrenheit, and a thermodynamics calc wants kelvin. Type 121 °C once and read 249.8 °F and 394.15 K together — no second- guessing a hand calculation at 2 a.m. The shareable link lets you send the exact setpoint to a colleague who opens the same conversion.

Temperature Converter — Celsius, Fahrenheit, Kelvin, Rankine

One temperature in, all four scales out — Celsius, Fahrenheit, Kelvin, Rankine — live formula, reference points, browser-only

Runs locally
Category Format Converter
Best for Turning pasted content or local files into a handoff-friendly format.

Type one temperature, read it in all four scales — Celsius, Fahrenheit, Kelvin and Rankine. The formula used for your input is shown live, with real reference points below. Nothing can go below absolute zero (−273.15 °C / 0 K); enter less and the tool flags it.

TemperatureInput scale

Conversions

Celsius

100°C

Input scale

Fahrenheit

212°F

°F = °C × 9/5 + 32

Kelvin

373.15K

K = °C + 273.15

Rankine

671.67°R

°R = (°C + 273.15) × 9/5

Reference points

Point	°C	°F	K	°R
Absolute zero	-273.15	-459.67	0	0
Water freezes	0	32	273.15	491.67
Body temperature	37	98.6	310.15	558.27
Water boils (sea level)	100	212	373.15	671.67
Room temperature	20	68	293.15	527.67
Crossover (°C = °F)	-40	-40	233.15	419.67

What this tool does

Free temperature converter that takes one reading in any scale and shows Celsius (°C), Fahrenheit (°F), Kelvin (K) and Rankine (°R) side by side. Type 100 °C and you instantly read 212 °F, 373.15 K and 671.67 °R; type a US weather forecast of 72 °F and read 22.22 °C. The page shows the exact formula it used for your conversion (F = C × 9/5 + 32, K = C + 273.15, and so on) so students can check their own work, and a table of real reference points — water freezing at 0 °C, boiling at 100 °C, body temperature 37 °C = 98.6 °F, absolute zero at -273.15 °C = 0 K. Enter anything below absolute zero and the tool flags it as physically impossible instead of printing a meaningless number. One-click copy and a shareable link that reopens the same value and scale. Everything runs in your browser; nothing is uploaded.

Tool details

Input: Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Format Converter · Student; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Temperature Converter fits into your work

Use it when the main problem is getting content from one practical format into another.

Conversion jobs

Turning pasted content or local files into a handoff-friendly format.
Previewing a conversion before you use it in a larger workflow.
Cleaning small format mismatches without opening a full editor.

Conversion checks

Try a small sample first when the source format is messy.
Check character encoding, separators, and line endings after conversion.
Keep the source until the converted output has been reviewed.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Read a US weather forecast in Celsius
You are traveling to the States and the app says it will be 95 °F tomorrow. Type 95 °F and read 35 °C — genuinely hot, pack accordingly. A forecast low of 41 °F is 5 °C, jacket weather. The four-scale readout means you never have to remember which direction the 9/5 goes; you just type the number you see and read the one you think in.
Follow an American recipe with a metric oven
A cookie recipe says bake at 350 °F but your oven dial is in Celsius. Type 350 °F and read 176.67 °C — set the dial to 175 or 180. Roasting at 425 °F is 218 °C, and a low-and-slow 225 °F is 107 °C. Pair this with the cooking unit converter when the same recipe also lists cups and sticks of butter.
Check a physics or chemistry homework answer
A problem gives a gas at 27 °C and asks for kelvin. Type 27 °C and read 300.15 K, with the formula K = C + 273.15 shown so you can see exactly why. Absolute-zero questions (−273.15 °C = 0 K) and the Rankine scale used in some engineering courses are all on the same screen, and anything below absolute zero is flagged as impossible.
Convert lab or industrial setpoints across scales
An autoclave datasheet specs 121 °C, a US-built furnace controller reads in Fahrenheit, and a thermodynamics calc wants kelvin. Type 121 °C once and read 249.8 °F and 394.15 K together — no second- guessing a hand calculation at 2 a.m. The shareable link lets you send the exact setpoint to a colleague who opens the same conversion.

Common pitfalls

Adding 32 before multiplying by 9/5. The order matters: F = C × 9/5 + 32, so you scale first, then shift. Doing (C + 32) × 9/5 turns 20 °C into 93.6 °F instead of the correct 68 °F. The tool shows the worked formula so the order is never in doubt.
Writing 300 °K with a degree symbol. Kelvin is an absolute unit, not a degree on a scale, so the SI convention is 300 K — no degree sign. Only Celsius, Fahrenheit and Rankine take the ° mark.
Confusing the Celsius-to-Kelvin offset 273.15 with 273. Rounding to 273 is fine for rough estimates but loses 0.15 K every time, which compounds in a multi-step calculation. Absolute zero is exactly −273.15 °C, not −273 °C.

Privacy

Every conversion runs as plain JavaScript inside your browser tab — the number you type never touches a server, and there is no logging of what you converted. The one caveat: the shareable link encodes your value and scale in the URL, so a link pasted into chat will record that temperature in the recipient server's access log. For anything sensitive, use the copy button and paste the text instead of sharing the URL.

FAQ

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Temperature Converter — Celsius, Fahrenheit, Kelvin, Rankine

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Temperature Converter fits into your work

Conversion jobs

Conversion checks

Good next steps

Real-world use cases

Read a US weather forecast in Celsius

Follow an American recipe with a metric oven

Check a physics or chemistry homework answer

Convert lab or industrial setpoints across scales

Common pitfalls

Privacy

FAQ

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