How to Convert Celsius to Fahrenheit

5 min read•June 1, 2025•Reviewed: June 1, 2026

✓Reviewed by Apex Conversion Editorial Team · Last reviewed June 1, 2026

The formula for converting Celsius to Fahrenheit is F = (C × 9/5) + 32. Multiply the Celsius temperature by 1.8 (which is 9 divided by 5) and then add 32. This covers all practical cases — weather, cooking, body temperature, and refrigerator settings.

For a quick mental estimate without a calculator: double the Celsius value and add 30. This gives a result within 2°F for temperatures between 5°C and 40°C, which covers the range of common everyday temperatures.

The Formula

°F = (°C × 9/5) + 32
   = (°C × 1.8) + 32

Worked examples:
   0°C: (0 × 1.8) + 32 =  32°F  (freezing)
  20°C: (20 × 1.8) + 32 = 68°F  (comfortable room)
  25°C: (25 × 1.8) + 32 = 77°F  (warm day)
  37°C: (37 × 1.8) + 32 = 98.6°F (body temperature)
 100°C: (100 × 1.8) + 32 = 212°F (boiling)

Mental shortcut: C × 2 + 30
  25°C → 50 + 30 = 80°F  (actual: 77°F)
  15°C → 30 + 30 = 60°F  (actual: 59°F)

Celsius to Fahrenheit Reference Table

°C    °F       °C    °F
────  ─────    ────  ─────
 −40  −40       20    68
 −20   −4       25    77
 −10   14       30    86
   0   32       35    95
   5   41       37   98.6
  10   50       40   104
  15   59      100   212
  18   64      180   356
  20   68      200   392

Step-by-Step Method

Step 1 — Multiply the Celsius value by 1.8 (or 9/5). For 25°C: 25 × 1.8 = 45. Step 2 — Add 32 to the result: 45 + 32 = 77°F. That is it. The multiplication step accounts for the different degree sizes between the two scales; the addition step accounts for the offset between their zero points.

If you do not have a calculator: multiply by 2 and subtract 10% of that result, then add 32. For 25°C: 50 − 5 = 45, + 32 = 77°F. This is more precise than the 'double and add 30' shortcut but requires one extra step.

Common Practical Conversions

Weather: 0°C (32°F) means freezing conditions. 10°C (50°F) is cool — bring a jacket. 20°C (68°F) is comfortable. 30°C (86°F) is hot. 40°C (104°F) is dangerous heat.

Cooking: most baking recipes from metric countries specify temperatures in Celsius. 160°C = 320°F (slow bake), 180°C = 356°F (standard cake temperature), 200°C = 392°F (hot roasting), 220°C = 428°F (very high heat for pizza and bread).

Quick Tips

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Memorize four key values: 0°C=32°F, 20°C=68°F, 37°C=98.6°F, 100°C=212°F.
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Oven temperatures from European recipes: divide by 5, multiply by 9, add 32. Or just look up the conversion — oven temperatures appear in most cookbooks.
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Body temperature: a child with a fever of 38.5°C has a temperature of 101.3°F.
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Your phone calculator: type the Celsius value, then × 1.8 + 32 = for a precise result.

Frequently Asked Questions

What is 30°C in Fahrenheit?

30°C × 1.8 + 32 = 54 + 32 = 86°F. A hot summer day in most climates.

What is 37°C in Fahrenheit?

37°C × 1.8 + 32 = 66.6 + 32 = 98.6°F — normal human body temperature.

Why do we add 32 in the formula?

Because the two scales have different zero points. Celsius zero is water's freezing point; Fahrenheit zero is a cold brine mixture. Water freezes at 32°F, so the 32 offset aligns the two scales at that reference point.