How do you convert delta degrees Fahrenheit to delta degrees Celsius?

• A. C = F / 1.8
• B. F = C / 1.8
• C. C = F × 1.8
• D. F = C × 1.0

Answer: (A)

Converting delta temperatures uses the fixed ratio between Fahrenheit and Celsius scales. A change of 1 degree Fahrenheit corresponds to a change of 5/9 degree Celsius, so to get the Celsius change from a Fahrenheit change you divide by 1.8 (or multiply by 5/9). That means the delta Celsius is ΔC = ΔF × 5/9, which is equivalently C = F / 1.8 when you’re given the Fahrenheit delta.

Note that the 32-degree offset matters for converting actual temperatures, not for changes—the offset cancels out for deltas.

The other forms would not preserve the correct scaling: dividing F by 1.8 to get C is the right approach; multiplying by 1.8 would exaggerate the change; using a 1.0 factor ignores the scale difference.