What are the Celsius ↔ Fahrenheit formulas?

Fahrenheit equals Celsius times 9/5 plus 32. Celsius equals Fahrenheit minus 32, then times 5/9. The scales meet at −40°, which is a handy mental check when signs look suspicious.

How does Kelvin relate to Celsius?

Kelvin equals Celsius plus 273.15. A kelvin interval matches a Celsius degree in size; only the zero point differs. SI style typically writes 300 K without a degree symbol, unlike °C and °F.

How do I convert Fahrenheit to Kelvin?

Convert Fahrenheit to Celsius first, then add 273.15. Direct combined algebra exists, but the two-step path reduces arithmetic mistakes when you already trust each half of the bridge.

Why is “twice as hot” misleading on Celsius or Fahrenheit?

Those scales have arbitrary zeros for everyday convenience. Doubling 10 °C is not a meaningful thermodynamic doubling of temperature. Convert to Kelvin (absolute scale) before arguing multiplicative heat relationships in physics.

Does this account for altitude when baking or boiling?

No. Conversion only changes unit labels. Water’s boiling point falls at altitude, and recipes may need time or temperature practice adjustments that sit outside unit math.

Is body-temperature conversion medical advice?

No. The tool can translate a number between °C and °F, but fever thresholds, measurement sites, and care decisions belong to medical guidance. Use conversion for communication clarity, not diagnosis.

Why do weather apps and oven dials still disagree after conversion?

Instrument calibration, rounding, probe placement, and whether an oven is preheated evenly introduce real differences. Conversion accuracy cannot fix a cold spot at the back of an oven or a sunny-window thermostat.

What is absolute zero in everyday scales?

Absolute zero is 0 K, which is −273.15 °C and −459.67 °F. Laboratory temperatures approach but do not casually reach that limit; the figure is a theoretical and metrological anchor.

Do Rankine or Réaumur scales appear here?

This converter focuses on Celsius, Fahrenheit, and Kelvin—the triad used most in modern weather, cooking, and science communication. Rankine (absolute Fahrenheit-sized) appears in some US engineering texts and needs its own factor if required.

How precise should I round converted temperatures?

Match the precision of the source and the decision. Forecasts rounded to whole degrees do not gain meaning from four decimal places after conversion. Analytical chemistry may keep finer resolution consistently across the notebook.

Can negative Fahrenheit values convert correctly?

Yes. The same affine formulas apply below zero. Extreme cold snaps in Fahrenheit become still lower Celsius readings, which sometimes surprises travelers reading foreign headlines.

Are calculations private in the browser?

Yes. Temperature arithmetic runs locally. That keeps homework and kitchen conversions offline from any need to upload readings.

Temperature Converter

Temperature scales disagree about zero points and degree sizes, so a weather app in Fahrenheit and an oven dial in Celsius can trip travelers and home cooks. This converter translates among Celsius (°C), Fahrenheit (°F), and Kelvin (K) using the familiar linear relationships taught in school science. Kelvin anchors absolute zero for physics and chemistry; Celsius and Fahrenheit remain everyday weather and kitchen scales. Conversion alone does not adjust baking for altitude, fever protocols, or climate-model offsets—those need separate judgment. Enter the reading you have, mark its scale, and read the equivalent on the other two so recipes, lab notes, and forecast discussions share one number story.

ValueFromTo

Result

32 °F

Informational only; verify critical results independently.

How to use

Enter the temperature number from a thermometer, oven display, weather report, or lab notebook.
Select whether that number is already in Celsius, Fahrenheit, or Kelvin so the formulas apply correctly.
Read the converted values on the other scales without re-entering the source figure.
For cooking, confirm whether a recipe means fan or conventional oven settings after you convert the dial number.
For science work, prefer Kelvin when equations need an absolute thermodynamic temperature rather than a comfort scale.
Double-check sign and magnitude for deep cold: negative Fahrenheit winter readings convert to still-colder Celsius values.
Avoid ratio language such as “twice as hot” on °C or °F; convert to Kelvin before discussing multiplicative factors in physics.
Round for the audience: weather often wants whole degrees; lab work may keep tenths or hundredths.
When converting fever readings, treat medical advice sources as authoritative—unit math is not a diagnosis.
Copy the converted value with its unit symbol so °C, °F, and K never collide in shared notes.

Examples

100 °C → 212 °F (water boiling at standard atmospheric pressure, sea-level idealization).
32 °F → 0 °C (water freezing under the same idealized reference).
0 K → −273.15 °C (absolute zero reference on the Celsius scale).
180 °C oven → 356 °F for adapting a metric recipe card to a US dial.
37.0 °C → 98.6 °F as a commonly cited oral body-temperature reference point.
20 °C room temperature → 68 °F for HVAC or travel packing discussions.
−40 °C → −40 °F (the unique crossing point of the two everyday scales).
300 K → 26.85 °C ≈ 80.33 °F for a quick lab-to-weather intuition check.
350 °F baking temperature → about 176.67 °C for a Celsius-marked oven.
273.15 K → 0 °C → 32 °F tying Kelvin’s water-ice point to both common scales.

FAQ

What are the Celsius ↔ Fahrenheit formulas?: Fahrenheit equals Celsius times 9/5 plus 32. Celsius equals Fahrenheit minus 32, then times 5/9. The scales meet at −40°, which is a handy mental check when signs look suspicious.
How does Kelvin relate to Celsius?: Kelvin equals Celsius plus 273.15. A kelvin interval matches a Celsius degree in size; only the zero point differs. SI style typically writes 300 K without a degree symbol, unlike °C and °F.
How do I convert Fahrenheit to Kelvin?: Convert Fahrenheit to Celsius first, then add 273.15. Direct combined algebra exists, but the two-step path reduces arithmetic mistakes when you already trust each half of the bridge.
Why is “twice as hot” misleading on Celsius or Fahrenheit?: Those scales have arbitrary zeros for everyday convenience. Doubling 10 °C is not a meaningful thermodynamic doubling of temperature. Convert to Kelvin (absolute scale) before arguing multiplicative heat relationships in physics.
Does this account for altitude when baking or boiling?: No. Conversion only changes unit labels. Water’s boiling point falls at altitude, and recipes may need time or temperature practice adjustments that sit outside unit math.
Is body-temperature conversion medical advice?: No. The tool can translate a number between °C and °F, but fever thresholds, measurement sites, and care decisions belong to medical guidance. Use conversion for communication clarity, not diagnosis.
Why do weather apps and oven dials still disagree after conversion?: Instrument calibration, rounding, probe placement, and whether an oven is preheated evenly introduce real differences. Conversion accuracy cannot fix a cold spot at the back of an oven or a sunny-window thermostat.
What is absolute zero in everyday scales?: Absolute zero is 0 K, which is −273.15 °C and −459.67 °F. Laboratory temperatures approach but do not casually reach that limit; the figure is a theoretical and metrological anchor.
Do Rankine or Réaumur scales appear here?: This converter focuses on Celsius, Fahrenheit, and Kelvin—the triad used most in modern weather, cooking, and science communication. Rankine (absolute Fahrenheit-sized) appears in some US engineering texts and needs its own factor if required.
How precise should I round converted temperatures?: Match the precision of the source and the decision. Forecasts rounded to whole degrees do not gain meaning from four decimal places after conversion. Analytical chemistry may keep finer resolution consistently across the notebook.
Can negative Fahrenheit values convert correctly?: Yes. The same affine formulas apply below zero. Extreme cold snaps in Fahrenheit become still lower Celsius readings, which sometimes surprises travelers reading foreign headlines.
Are calculations private in the browser?: Yes. Temperature arithmetic runs locally. That keeps homework and kitchen conversions offline from any need to upload readings.

Formula / Method

°F = °C × 9/5 + 32; °C = (°F − 32) × 5/9; K = °C + 273.15; °C = K − 273.15. Combined: K = (°F − 32) × 5/9 + 273.15. Interval sizes: 1 K = 1 °C interval; 1 °C interval = 1.8 °F interval. Landmark checks: 0 °C = 32 °F = 273.15 K; −40 °C = −40 °F; 0 K = −273.15 °C. These are affine unit changes, not volume conversions such as gallons.

Assumptions & Limitations

Conversion assumes the stated formulas under standard scale definitions. It does not model altitude boiling points, wet-bulb comfort indices, thermostat lag, medical protocols, or climate normals. Kelvin below zero is physically invalid; treat nonsense inputs as user error. Specialized historical scales are omitted. Results are for unit translation only.

Related guides

Unit Conversion Basics: Length, Weight, and Temperature
Convert metric and imperial length, mass, and temperature with exact factors, worked examples, and free online converters.

Related tools

Last updated: 2026-07-13

← Back to Unit Converters