The Complete Guide to Temperature Conversions

Consider this the master page for temperature conversions. Below you'll find every supported unit explained, the precise factors connecting them, and computed tables you can rely on for homework, work or travel.

Prefer a calculator? Every conversion on this page has an instant, free tool — start at the tools hub or use the links under each unit below.

The units at a glance

Celsius (°C)

Celsius sets 0° at water's freezing point and 100° at its boiling point at sea level. It is the world's standard scale for weather and cooking outside the US.

• 1 °C = see formula below — Celsius to Fahrenheit converter
• 1 °C = see formula below — Celsius to Kelvin converter

Fahrenheit (°F)

Fahrenheit places freezing at 32° and boiling at 212°, giving 180 finer-grained degrees between them. It remains the everyday scale of the United States.

• 1 °F = see formula below — Fahrenheit to Celsius converter
• 1 °F = see formula below — Fahrenheit to Kelvin converter

Kelvin (K)

The kelvin starts at absolute zero (−273.15 °C), the coldest temperature physically possible. It is the SI base unit used throughout science.

• 1 K = see formula below — Kelvin to Celsius converter
• 1 K = see formula below — Kelvin to Fahrenheit converter

Every conversion formula

The table below lists the exact formula for every temperature pair we support. Temperature scales differ by offsets as well as ratios, so each direction has its own formula.

One-line cross reference: every unit in every other unit

The complete pairwise reference — every supported temperature unit expressed in each of the others:

• 1 °C = 33.8 °F (°F = °C × 9/5 + 32)
• 1 °C = 274.15 K (K = °C + 273.15)
• 1 °F = -17.22 °C (°C = (°F − 32) × 5/9)
• 1 °F = 255.93 K (K = (°F − 32) × 5/9 + 273.15)
• 1 K = -272.15 °C (°C = K − 273.15)
• 1 K = -457.87 °F (°F = (K − 273.15) × 9/5 + 32)

Real-world reference points

Memorable reference points: −40° is where Celsius and Fahrenheit agree, 0 °C / 32 °F is freezing, 20–22 °C / 68–72 °F is room temperature, 37 °C / 98.6 °F is body temperature, and 100 °C / 212 °F is water boiling at sea level. These five anchors let you sanity-check any conversion instantly.

Most-used conversion tables

Celsius to Fahrenheit

Fahrenheit to Celsius

Fahrenheit to Kelvin

Kelvin to Fahrenheit

Common mistakes to avoid

The classic temperature mistakes: applying the ×9/5 ratio without adding the 32 offset (or vice versa), using the weather shortcut ("double and add 30") in cooking where its error matters, and forgetting that temperature differences convert differently than temperatures — a change of 10 °C is a change of 18 °F, not 50 °F.

Tips for accurate conversions

• Round once, at the end. Chaining conversions and rounding each step compounds error surprisingly fast.
• Watch for regional unit variants. Scientific work uses kelvin; weather in the US uses Fahrenheit; almost everywhere else uses Celsius.
• Estimate first, then compute. A rough mental figure catches order-of-magnitude mistakes before they end up in your work.
• Use exact factors for anything official. The factors in this guide are the internationally defined values, not approximations.

Frequently asked questions

Which temperature unit should I use?

Use the unit your audience expects: metric units for international and scientific audiences, US customary units for American everyday contexts. When in doubt, give both — "5 km (3.1 mi)" style.

Are these conversion factors exact?

Yes. Every factor on this page comes from the internationally agreed definition of the units involved, so the only inaccuracy is the rounding you choose for the final answer.

Can I use these tables offline?

Yes — print this page or save it as a PDF. The tables are computed from exact factors and will not go out of date.