Temperature Converter

Convert any temperature into Celsius, Fahrenheit, Kelvin and Rankine at once. Absolute zero is enforced, formulas use your numbers, and reference charts cover freezing, body heat, boiling and oven settings.

Temperature

Enter one value; all four scales appear in the result

Unit

How the four temperature scales connect

Celsius and Fahrenheit are everyday relative scales; Kelvin and Rankine are absolute scales that start at absolute zero. This converter routes every input through kelvin so the four outputs stay consistent, then shows the algebra with the value you typed — not generic placeholders.

The Formula

°C = (°F − 32) × 5/9
°F = °C × 9/5 + 32
K = °C + 273.15
°R = °F + 459.67 = K × 9/5

Absolute zero: 0 K = 0 °R = −273.15 °C = −459.67 °F

Worked Example

Body temperature 98.6 °F
(98.6 − 32) × 5/9 = 37 °C. Kelvin = 37 + 273.15 = 310.15 K. Rankine = 98.6 + 459.67 = 558.27 °R.
The −40 crossover
−40 °C × 9/5 + 32 = −40 °F. The scales meet at that single point.
Absolute zero
0 K = −273.15 °C = −459.67 °F = 0 °R. Anything colder is rejected.

Tips, Assumptions & Limitations

Use Kelvin for scientific formulas that need absolute temperature.
Cooking charts often list °C and °F side by side — the oven rows below match common settings.
For weather “feels like” numbers, open Heat Index or Wind Chill instead of raw air temperature alone.

Reference temperatures

Landmark	°C	°F	K	°R
Absolute zero	-273.15	-459.67	0	0
Freezing point of water	0	32	273.15	491.67
Room temperature (≈20 °C)	20	68	293.15	527.67
Body temperature (37 °C)	37	98.6	310.15	558.27
Boiling point of water	100	212	373.15	671.67
Oven 180 °C	180	356	453.15	815.67
Oven 200 °C	200	392	473.15	851.67
Oven 220 °C	220	428	493.15	887.67

−40 °C to 100 °C chart (5° steps)

°C	°F	K	°R
-40	-40	233.15	419.67
-35	-31	238.15	428.67
-30	-22	243.15	437.67
-25	-13	248.15	446.67
-20	-4	253.15	455.67
-15	5	258.15	464.67
-10	14	263.15	473.67
-5	23	268.15	482.67
0	32	273.15	491.67
5	41	278.15	500.67
10	50	283.15	509.67
15	59	288.15	518.67
20	68	293.15	527.67
25	77	298.15	536.67
30	86	303.15	545.67
35	95	308.15	554.67
40	104	313.15	563.67
45	113	318.15	572.67
50	122	323.15	581.67
55	131	328.15	590.67
60	140	333.15	599.67
65	149	338.15	608.67
70	158	343.15	617.67
75	167	348.15	626.67
80	176	353.15	635.67
85	185	358.15	644.67
90	194	363.15	653.67
95	203	368.15	662.67
100	212	373.15	671.67

FAQ

Celsius (°C), Fahrenheit (°F), Kelvin (K) and Rankine (°R). Enter one value and unit; the page shows all four together with the working formula using your numbers.

Absolute zero is 0 K (also 0 °R), equal to −273.15 °C or −459.67 °F. Nothing can be colder; values below that threshold return a clear error instead of nonsense numbers.

The Celsius and Fahrenheit scales cross at −40. From °C to °F you multiply by 9/5 and add 32: (−40)×9/5 + 32 = −72 + 32 = −40. The same point appears in the −40 to 100 °C chart below.

Both are absolute scales starting at absolute zero. Rankine degrees are the same size as Fahrenheit degrees: °R = K × 9/5, and °R = °F + 459.67.

Kelvin is the SI unit for thermodynamic temperature. Gas laws, black-body radiation and most lab equations expect kelvin because ratios and differences stay physically meaningful from absolute zero.

Related Calculators

Fahrenheit to Celsius Heat Index Converter Wind Chill Converter Dew Point Converter Length Area Volume Weight Cooking Currency Power Radian to Degree

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Temperature Conversion Made Easy

How this calculator works

Temperature scales use different zero points and step sizes, so they are **not** proportional like meters and feet. Treat conversions as affine transforms: multiply then add (or the inverse).

Explanation

Celsius and Fahrenheit relate through a linear map with offset 32°F at freezing and a 9/5 slope between boiling and freezing spans. Kelvin shares Celsius-sized degrees but anchors at absolute zero. Because of the offset, **doubling** a Fahrenheit number has no physical meaning—always convert to a thermodynamic-friendly unit before reasoning about ratios.

Formula

°F = °C × 9/5 + 32; °C = (°F − 32) × 5/9; K = °C + 273.15.

Worked example

Human body temperature near 37°C maps to 98.6°F via the affine formula—not by multiplying by a single conversion factor like length units.

How to use this tool

Use the Temperature calculator: enter a value, choose the unit you are converting from and to, then read the equivalent. When comparing weather forecasts, stick to one scale per comparison so offsets do not confuse large versus small changes.

Frequently asked questions

Can I use dimensional analysis like meters to inches?: Not with a lone multiply-only factor across Celsius and Fahrenheit because of the additive offset. Kelvin-to-Celsius only needs addition once you respect absolute zero.
Which scale should scientists standardize on?: Kelvin for thermodynamics and chemistry ratios; Celsius for everyday weather deltas once contextualized.

Read the full guide →