Degrees Celsius to degrees Fahrenheit converter

A Celsius reading may describe weather, a room or an oven setting. Temperature scales use different zero points, so a ratio alone is insufficient. Converting a temperature reading is also different from converting a temperature difference, where the offset cancels.

Multiply by 9/5 (1.8) and add 32: 37 °C × 1.8 + 32 = 98.6 °F. The 1.8 is the ratio of degree sizes and the 32 is the offset between the two zero points.

Double the Celsius value and add 30. It is exact at 10 °C (50 °F) and drifts by 1 °F for every 5 °C away from 10: at 20 °C it gives 70 °F instead of 68 °F, and at 30 °C it gives 90 °F instead of 86 °F.

Exactly 98.6 °F: 37 × 1.8 + 32 = 98.6. 37 °C is the traditional figure for normal human body temperature, from Carl Wunderlich's 1868 study.

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “37 °C to °F” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.