Temperature converter

Convert temperatures instantly across common and historical scales

Edit any row to update the others

Last updated: February 9, 2026

CreatorFrank Zhao

Temperature converter

Type in any row or use − / + to step

Kelvin

Celsius

°C

Fahrenheit

°F

Rankine

°R

Delisle

°De

Newton

°N

Réaumur

°Ré

Rømer

°Rø

Introduction / overview

The Temperature Converter lets you type a value in one scale and instantly see the equivalent values in the others. It supports the everyday standards (Celsius, Fahrenheit, Kelvin) plus a few historical scales (Rankine, Delisle, Newton, Réaumur, and Rømer).

Use it when you want quick, consistent conversions—without hunting for the “right” formula each time.

Who is this for?

Students double-checking homework or lab notes
Home cooks converting oven temperatures between °F and °C
Engineers and makers reading datasheets in mixed units
Anyone sanity-checking absolute zero, freezing, and boiling points

Why the results are reliable

The calculator converts everything through a single reference scale (Kelvin). That means you’re always using consistent, well-known relationships instead of a patchwork of pairwise formulas.

Helpful companion calculators

If you’re doing PCR or protocol work, pair this with our Annealing Temperature Calculator to connect lab targets (like annealing temperatures) to whichever unit your instrument expects.

How to use / quick start

1Pick the row that matches the unit you have (for example, Fahrenheit).
2Type your temperature value in that row.
3Read the converted values in the other rows immediately.
4Use the − / + buttons to nudge a value up or down by 1 unit.
5Use the Reset button if you want to start over.

Quick sanity checks

$0\ ^\circ\mathrm{C}$ ≈ $32\ ^\circ\mathrm{F}$
$100\ ^\circ\mathrm{C}$ ≈ $212\ ^\circ\mathrm{F}$
$0\ \mathrm{K}$ ≈ $-273.15\ ^\circ\mathrm{C}$

Real-world examples / worked conversions

Example 1: Oven temperature (°F → °C)

You have a recipe calling for 350 °F and your oven uses °C.

C = (F - 32)\,\frac{5}{9}

=

(350 - 32)\,\frac{5}{9}

=

176.67\ ^\circ\mathrm{C}

In practice you’d set the oven to about $177\ ^\circ\mathrm{C}$ .

Example 2: Absolute zero (K → °C)

You see a value in Kelvin and want the everyday Celsius meaning.

C = K - 273.15

C

=

0 - 273.15

=

-273.15\ ^\circ\mathrm{C}

Example 3: Quick check (°C ↔ °F)

A handy mental anchor: every 5 °C is about 9 °F.

F = C\,\frac{9}{5} + 32

For example, $20\ ^\circ\mathrm{C}$ maps to $68\ ^\circ\mathrm{F}$ .

Real-world use cases

Travel and weather apps

Weather forecasts may use $^\circ\mathrm{C}$ or $^\circ\mathrm{F}$ depending on region.

Lab and protocols

Convert setpoints or reporting units for experiments (especially when a device expects Kelvin).

Industrial datasheets

Some specs and standards still show Rankine or older scales. Converting through Kelvin keeps it consistent.

Engineering sanity checks

Quick checks around key points like $0\ ^\circ\mathrm{C}$ (freezing) and $100\ ^\circ\mathrm{C}$ (boiling).

Common scenarios / when to use

Cooking

Convert oven or candy temperatures between °F and °C.

Freezing points

Check near-freezing temperatures quickly.

Heating

Convert setpoints for heaters and thermostats.

Science

Switch between Kelvin and Celsius in reporting.

Calibration

Compare readings from devices with different units.

Quick validation

Sanity-check outputs around known reference points.

When this might not be the right tool: if you’re converting temperature differences (like “a 10 °C change”), be careful—offset scales behave differently for differences.

Tips & best practices

Use Kelvin for scientific work: it avoids the “+32” style offsets.
Sanity-check with freezing and boiling anchors before trusting a long chain of conversions.
If you see surprising values, check whether the input is absolute temperature or a temperature difference.
For quick cooking conversions, rounding to the nearest whole degree is usually enough.

Calculation method / formula explanation

Internally, everything converts through Kelvin. Here are the core relationships used.

Celsius ↔ Kelvin

C = K - 273.15

K = C + 273.15

Fahrenheit ↔ Celsius

F = C\,\frac{9}{5} + 32

C = (F - 32)\,\frac{5}{9}

Rankine (absolute Fahrenheit)

R = K\,\frac{9}{5}

K = R\,\frac{5}{9}

Historical scales

Delisle: $De = (373.15 - K)\,\frac{3}{2}$

Newton: $N = (K - 273.15)\,\frac{33}{100}$

Réaumur: $Re = (K - 273.15)\,\frac{4}{5}$

Rømer: $Ro = (K - 273.15)\,\frac{21}{40} + 7.5$

Related concepts / background

Absolute vs. relative temperature

Kelvin and Rankine are absolute scales: they start at absolute zero. Celsius and Fahrenheit are offset scales: they define zero at a convenient reference point (water freezing, historically). That’s why formulas like $F = C\,\frac{9}{5} + 32$ include an offset.

Frequently asked questions (FAQs)

Why does Kelvin have no degree symbol?

Kelvin is an absolute thermodynamic scale. The SI unit is written as $\mathrm{K}$ (not $^\circ\mathrm{K}$ ).

What’s the fastest way to estimate °C ↔ °F?

Use the exact formula $F = C\,\frac{9}{5} + 32$ for accuracy, or remember that every $5\ ^\circ\mathrm{C}$ step is about $9\ ^\circ\mathrm{F}$ .

Can Kelvin be negative?

In physical thermodynamics, Kelvin is defined from absolute zero, so negative Kelvin isn’t used in normal temperature contexts. If you enter values below absolute zero on an offset scale, the math may produce a negative Kelvin value—treat that as a signal to re-check the input.

Why do some scales look “backwards”?

Delisle increases as it gets colder (by definition). That’s why its conversion contains $(373.15 - K)$ .

Does rounding matter?

For cooking and everyday tasks, rounding to the nearest whole degree is typically fine. For lab work, keep the decimal precision specified by your protocol.

Limitations / disclaimers

This converter performs mathematical unit conversion only. It doesn’t account for measurement error, sensor calibration, or context-specific definitions. It’s not a substitute for professional advice when safety or compliance depends on temperature thresholds.

External references / sources

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