Fahrenheit to Celsius | °F to °C Converter

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Fahrenheit ↔ Celsius Converter

Convert between Fahrenheit and Celsius instantly. Useful for weather, cooking, science, and everyday temperature comparisons.

Last updated: March 2026 | By Patchworkr Team

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What is Fahrenheit to Celsius?

Fahrenheit and Celsius are two different temperature scales. Celsius is a relative scale based on water's freezing (0°C) and boiling (100°C) points. Fahrenheit is also relative, but uses different reference points.

The two scales differ in two ways:

  • Different zero points: Celsius sets 0° at water's freezing point, while Fahrenheit sets 0° much colder (at a brine mixture's freezing point).
  • Different degree sizes: A 1°C change is larger than a 1°F change. Specifically, a 1°C increment equals a 1.8°F increment.

Water freezes at 0°C = 32°F and boils at 100°C = 212°F.

In both scales, absolute zero (the lowest possible temperature) occurs at −273.15°C or −459.67°F.

How it works

Formula #1: Standard form (°F → °C)

°C = (°F − 32) × 5/9

First subtract 32 to undo the offset, then multiply by 5/9 to scale down.

Formula #2: Decimal form (equivalent)

°C = (°F − 32) × 0.5556

Same result as formula #1 (since 5/9 ≈ 0.5556). Use whichever is more convenient.

Reverse formula (°C → °F)

°F = (°C × 9/5) + 32

Scale up by 9/5, then add 32 to shift to Fahrenheit baseline.

Fast mental estimate (less accurate but faster)

(°F − 30) ÷ 2 ≈ °C

Roughly 10% off but works well for everyday weather temperatures.

How to convert 86°F to Celsius

Convert 86°F to Celsius (step-by-step)

Step 1: Subtract 32

86 − 32 = 54

Step 2: Multiply by 5/9 (or 0.5556)

54 × 5/9 = 30
30°C

Quick Reference

32°F = 0°C
50°F = 10°C
68°F = 20°C
77°F = 25°C
86°F = 30°C
104°F = 40°C
-40°F = -40°C

Frequently Asked Questions

Which formula is better: 5/9 or 0.5556?

They give identical results. Use whichever is more convenient. 0.5556 is simpler; 5/9 shows the underlying ratio.

How do I convert Fahrenheit to Celsius quickly?

Subtract 32, then multiply by 5/9 (or 0.5556).

What's a quick mental estimate?

Subtract 30 and divide by 2. This is roughly 10% off but works well for everyday weather temperatures.

When are Fahrenheit and Celsius the same?

-40°.

Is 70°F hot or cold?

About 21°C — comfortable room temperature.

Why does Fahrenheit use 32 as a base?

It was defined using older reference points before modern standards.

What is 100°F in Celsius?

About 37.8°C.

Can I use this for cooking?

Yes—especially when converting oven temps from US recipes.

Is Celsius used worldwide?

Yes, almost everywhere outside the US.

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