−40 °C to Fahrenheit.
−40 °C = −40 °F. −40 is the one temperature where the Celsius and Fahrenheit scales show the same number.
What −40 °C means
- −40 °C is 40 °C below the freezing point of water (0 °C, 32 °F).
- −40 °C is 77 °C below the generally accepted average normal body temperature (37 °C, 98.6 °F).
- −40 °C is 140 °C below the boiling point of water at sea level, rounded to 100 °C (212 °F).
- In wind, −40 °C feels colder. Use the wind chill calculator to see how cold.
How to convert
- Multiply by 9/5 (1.8): −40 × 1.8 = −72.
- Add 32: −72 + 32 = −40 °F.
To convert the other way, use the Fahrenheit to Celsius converter.
Nearby values
| Celsius | Fahrenheit |
|---|---|
| −45 °C | −49 °F |
| −44 °C | −47.2 °F |
| −43 °C | −45.4 °F |
| −42 °C | −43.6 °F |
| −41 °C | −41.8 °F |
| −40 °C | −40 °F |
| −39 °C | −38.2 °F |
| −38 °C | −36.4 °F |
| −37 °C | −34.6 °F |
| −36 °C | −32.8 °F |
| −35 °C | −31 °F |
Questions people ask
What is −40 °C in °F?
−40 °C is −40 °F.
Is −40 °C above body temperature?
No. It is 77 °C below it. The generally accepted average normal body temperature is 37 °C (98.6 °F).
How do I estimate −40 °C in °F in my head?
Double the °C and add 30. That gives −50 °F. The exact value is −40 °F, so the error is 10 °F.
Sources: °F = °C × 9/5 + 32, exact (NIST SP 811); body temperature: MedlinePlus (NIH): Body temperature norms.
Sources & verification
Unit definitions used by this converter:
- Temperature scales: T/K = t/°C + 273.15; t/°C = (t/°F − 32)/1.8; T/K = (t/°F + 459.67)/1.8; °R = K × 9/5, exact — NIST SP 811, Appendix B.8
Other Celsius to Fahrenheit values
−20 °C · −15 °C · −10 °C · 0 °C · 10 °C · 15 °C · 16 °C · 18 °C · 19 °C · 20 °C · 21 °C · 22 °C · 23 °C · 24 °C · 25 °C · 27 °C · 28 °C · 30 °C · 32 °C · 33 °C · 35 °C · 36 °C · 36.9 °C · 37 °C · 37.2 °C · 37.7 °C · 38 °C · 38.5 °C · 40 °C · 42 °C · 45 °C · 70 °C · 100 °C · 160 °C · 170 °C · 180 °C · 190 °C · 200 °C · 220 °C