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Temperature Converter

Convert between Celsius, Fahrenheit, Kelvin, Rankine and Réaumur — type once, see all five scales instantly. Plus oven temperatures, the UK gas mark chart, and every formula worked out step by step.

◈Convert temperature

Enter a value and pick its scale — every other scale updates live, with an oven guide when your temperature is in cooking range.

Temperature value

From scale

🔥 Oven guide for this temperature

100°C

◈Oven temperature conversion & gas mark chart

The full UK gas mark chart with conventional, Fahrenheit and fan-assisted equivalents — plus the temperatures real recipes actually use.

Fan vs conventional rule: for a fan-assisted (convection) oven, reduce the conventional temperature by 20°C (about 35°F). The chart's fan column already applies this. For air fryers, reduce by ~20°C and check a few minutes early.

Gas mark	Conventional °C	°F	Fan °C	Best for
1/4	110	225	90	Meringues, slow drying
1/2	130	250	110	Rich fruit cake
1	140	275	120	Slow roast, braising
2	150	300	130	Baked custards
3	170	325	150	Shortbread, pastry
4	180	350	160	Cakes & cookies
5	190	375	170	Roast chicken, pies
6	200	400	180	Bread rolls, scones
7	220	425	200	Bread, roast veg
8	230	450	210	Puff pastry, searing
9	240	475	220	Pizza, flatbreads

Common cooking temperatures

What you're cooking	°C	°F	Gas mark
Meringues, drying herbs	110	225	¼
Slow roast, braising	140	275	1
Cakes & cookies	180	350	4
Roast chicken	190	375	5
Bread & roast veg	220	425	7
Pizza, flatbreads	240	475	9

◈Reference: landmark temperatures in every scale

Absolute zero, freezing and boiling points, body temperature and more — converted exactly.

Landmark	°C	°F	K	°R	°Ré
Absolute zero	-273.15	-459.67	0	0	-218.52
Dry ice sublimates	-78.5	-109.3	194.65	350.37	-62.8
Water freezes	0	32	273.15	491.67	0
Fridge temperature	4	39.2	277.15	498.87	3.2
Room temperature	20	68	293.15	527.67	16
Comfortable room	22	71.6	295.15	531.27	17.6
Human body temperature	37	98.6	310.15	558.27	29.6
Fever threshold	38	100.4	311.15	560.07	30.4
Hot summer day	40	104	313.15	563.67	32
Water boils (sea level)	100	212	373.15	671.67	80
Typical baking oven	180	356	453.15	815.67	144
Pizza oven	240	464	513.15	923.67	192

◈Formulas & worked examples

Every conversion formula, with three fully worked examples.

Celsius → Fahrenheit

°F = °C × 9/5 + 32

Fahrenheit → Celsius

°C = (°F − 32) × 5/9

Celsius ⇄ Kelvin

K = °C + 273.15

→ Rankine

°R = (°C + 273.15) × 9/5

→ Réaumur

°Ré = °C × 4/5

Example 1 — Boiling water: 100°C to everything

Fahrenheit: 100 × 9/5 + 32 = 180 + 32 = 212°F
Kelvin: 100 + 273.15 = 373.15 K
Rankine: 373.15 × 9/5 = 671.67°R
Réaumur: 100 × 4/5 = 80°Ré — the scale's boiling point by definition

Answer: 100°C = 212°F = 373.15 K = 671.67°R = 80°Ré

Example 2 — The −40° crossover

Set the scales equal: x = 9/5·x + 32
Rearrange: x − 9/5·x = 32 → −4/5·x = 32
Solve: x = 32 × (−5/4) = −40

Answer: −40°C = −40°F — the only temperature where both scales agree (233.15 K).

Example 3 — A US baking recipe: 350°F to Celsius + gas mark

Celsius: (350 − 32) × 5/9 = 318 × 5/9 = 176.67°C ≈ 177°C
Recipes round to the nearest standard oven step: 180°C
Gas mark chart: 180°C is Gas Mark 4; fan oven: 160°C

Answer: 350°F ≈ 177°C → bake at 180°C / Gas Mark 4 (160°C fan).

◈Quick chart: Celsius to Fahrenheit

Every 5°C from freezing to boiling — for when you just need the number.

°C	°F	°C	°F	°C	°F
0	32	5	41	10	50	15	59	20	68	25	77	30	86
35	95	40	104	45	113	50	122	55	131	60	140	65	149
70	158	75	167	80	176	85	185	90	194	95	203	100	212

◈Temperature conversion FAQs

Answers to the questions people ask most about converting temperatures.

What is the formula to convert Celsius to Fahrenheit?

Multiply the Celsius temperature by 9/5 (1.8) and add 32: °F = °C × 9/5 + 32. Example: 25°C × 9/5 = 45, plus 32 = 77°F. The converter above applies this exact formula and shows all five scales at once.

What is the formula to convert Fahrenheit to Celsius?

Subtract 32 from the Fahrenheit temperature, then multiply by 5/9: °C = (°F − 32) × 5/9. Example: (68°F − 32) = 36, × 5/9 = 20°C. This is the inverse of the Celsius-to-Fahrenheit formula.

How do I convert Celsius to Fahrenheit in my head without a calculator?

Use this shortcut: double the Celsius number, subtract 10% of that doubled value, then add 32. Example: 20°C → double = 40, minus 10% (4) = 36, plus 32 = 68°F — exactly right. For Fahrenheit to Celsius, reverse it: subtract 32, then take roughly half and add 10%.

How do I convert Kelvin to Celsius?

Subtract 273.15: °C = K − 273.15. To go the other way, add 273.15: K = °C + 273.15. Example: 300 K − 273.15 = 26.85°C (a warm room). Kelvin never uses the degree symbol — write “300 K”, not “300°K”.

What is the Rankine scale?

Rankine (°R) is the absolute-temperature version of Fahrenheit: each Rankine degree is the same size as a Fahrenheit degree, but it starts at absolute zero. Convert with °R = °F + 459.67. So water freezes at 491.67°R and boils at 671.67°R. It is still used in some US engineering and thermodynamics work.

What is the Réaumur scale?

Réaumur (°Ré) is a historical scale where water freezes at 0°Ré and boils at 80°Ré, so 1°Ré = 1.25°C. Convert with °C = °Ré × 5/4. It is rarely used today except in some European cheese-making and liquor traditions.

What is −40°C in Fahrenheit?

−40°F — minus 40 is the single point where the Celsius and Fahrenheit scales meet. You can verify it: −40 × 9/5 + 32 = −72 + 32 = −40. It is also 233.15 K.

What gas mark is 180°C or 350°F?

Gas Mark 4. The standard chart pairs Gas Mark 4 with 180°C conventional (350°F); in a fan (convection) oven use 160°C. Note 350°F converts to 176.67°C exactly, which recipes round to 180°C — the oven section above shows the full gas-mark table from ¼ to 9.

Should I reduce the temperature for a fan (convection) oven?

Yes. Reduce the conventional-oven temperature by 20°C (about 35°F) for a fan-assisted oven, because circulating air transfers heat more efficiently. Example: a recipe calling for 200°C conventional becomes 180°C fan. The converter's oven panel applies this rule automatically.

What is room temperature in Celsius and Fahrenheit?

Room temperature is generally 20–25°C, which is 68–77°F. Scientific work often standardizes on 20°C (68°F) or 25°C (77°F). In Kelvin that is 293.15–298.15 K.

What is normal body temperature in Fahrenheit and Celsius?

Average normal body temperature is 37°C, which equals 98.6°F. A fever is generally defined as 38°C (100.4°F) or higher. Individual readings vary through the day, so a single reading slightly above or below 98.6°F is usually normal.

Why does America use Fahrenheit instead of Celsius?

The Fahrenheit scale (1724) predates Celsius (1742) and was already entrenched in Britain's colonies when the US formed. The US never completed the metric switch that most countries made in the 19th–20th centuries, so Fahrenheit stayed for weather, cooking, and daily life — while US science, medicine, and the military use Celsius.

What is 350°F in Celsius for baking?

350°F = 176.67°C, which ovens and recipes round to 180°C (Gas Mark 4; 160°C fan). For an air fryer, reduce by about 20°C and start checking a few minutes early — so 350°F recipes typically cook well at 160°C in an air fryer.

What is the lowest possible temperature?

Absolute zero: 0 K = −273.15°C = −459.67°F = 0°R. It is the point where all thermal motion stops. The converter rejects any input below absolute zero because such a temperature cannot physically exist.

How do I convert oven temperatures from Celsius to Fahrenheit?

Use °F = °C × 9/5 + 32. Common pairs: 180°C → 356°F (recipes say 350°F), 200°C → 392°F (recipes say 400°F), 220°C → 428°F (recipes say 425°F). Recipes round to the nearest convenient 25°F mark — the gas-mark table above lists the standard rounded pairs.

Is 0 Kelvin actually reachable?

No — absolute zero is a theoretical limit. The third law of thermodynamics says it cannot be reached, only approached; the coldest lab temperatures are fractions of a kelvin above 0 K. In outer space, the cosmic background keeps things around 2.7 K.

How do I convert Celsius to Fahrenheit in Excel?

Use =CONVERT(A1,"C","F") to convert the value in A1 from Celsius to Fahrenheit, or the plain formula =(A1*9/5)+32. For Fahrenheit to Celsius use =CONVERT(A1,"F","C") or =(A1-32)*5/9. CONVERT also handles "K" for kelvin.

Scope note: this is a general temperature converter covering all five scales, with oven conversion as one of its angles. Our separate oven-temperature-converter tool goes deeper on cooking-only temperature help (roasting charts, meat doneness, baking adjustments). This tool never overlaps it — it converts first, cooks second.

Temperature Converter

◈Convert temperature

🔥 Oven guide for this temperature

◈Oven temperature conversion & gas mark chart

Common cooking temperatures

◈Reference: landmark temperatures in every scale

◈Formulas & worked examples

Example 1 — Boiling water: 100°C to everything

Example 2 — The −40° crossover

Example 3 — A US baking recipe: 350°F to Celsius + gas mark

◈Quick chart: Celsius to Fahrenheit

◈Temperature conversion FAQs

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°C	°F	°C	°F	°C	°F
0	32	5	41	10	50	15	59	20	68	25	77	30	86
35	95	40	104	45	113	50	122	55	131	60	140	65	149
70	158	75	167	80	176	85	185	90	194	95	203	100	212

°C	°F	°C	°F	°C	°F
0	32	5	41	10	50	15	59	20	68	25	77	30	86
35	95	40	104	45	113	50	122	55	131	60	140	65	149
70	158	75	167	80	176	85	185	90	194	95	203	100	212

°C	°F	°C	°F	°C	°F
0	32	5	41	10	50	15	59	20	68	25	77	30	86
35	95	40	104	45	113	50	122	55	131	60	140	65	149
70	158	75	167	80	176	85	185	90	194	95	203	100	212