Fahrenheit to Celsius Conversion: The Chart Power Station Engineers Need
A Fahrenheit to Celsius conversion is trivial arithmetic, C = 5/9 x (F minus 32), and consequential engineering. Nameplates, OEM derating curves, and international standards are written in Celsius. Site data from the United States arrives in Fahrenheit. Reading one as the other is how a plant gets specified for a temperature it will never see. The chart below runs from 0F to 120F.
Fahrenheit to Celsius Conversion Chart
| Deg F | Deg C | Deg F | Deg C |
| 0 | -18 | 61 | 16 |
| 1 | -17 | 62 | 17 |
| 2 | -17 | 63 | 17 |
| 3 | -16 | 64 | 18 |
| 4 | -16 | 65 | 18 |
| 5 | -15 | 66 | 19 |
| 6 | -14 | 67 | 19 |
| 7 | -14 | 68 | 20 |
| 8 | -13 | 69 | 21 |
| 9 | -13 | 70 | 21 |
| 10 | -12 | 71 | 22 |
| 11 | -12 | 72 | 22 |
| 12 | -11 | 73 | 23 |
| 13 | -11 | 74 | 23 |
| 14 | -10 | 75 | 24 |
| 15 | -9 | 76 | 24 |
| 16 | -9 | 77 | 25 |
| 17 | -8 | 78 | 26 |
| 18 | -8 | 79 | 26 |
| 19 | -7 | 80 | 27 |
| 20 | -7 | 81 | 27 |
| 21 | -6 | 82 | 28 |
| 22 | -6 | 83 | 28 |
| 23 | -5 | 84 | 29 |
| 24 | -4 | 85 | 29 |
| 25 | -4 | 86 | 30 |
| 26 | -3 | 87 | 31 |
| 27 | -3 | 88 | 31 |
| 28 | -2 | 89 | 32 |
| 29 | -2 | 90 | 32 |
| 30 | -1 | 91 | 33 |
| 31 | -1 | 92 | 33 |
| 32 | 0 | 93 | 34 |
| 33 | 1 | 94 | 34 |
| 34 | 1 | 95 | 35 |
| 35 | 2 | 96 | 36 |
| 36 | 2 | 97 | 36 |
| 37 | 3 | 98 | 37 |
| 38 | 3 | 99 | 37 |
| 39 | 4 | 100 | 38 |
| 40 | 4 | 101 | 38 |
| 41 | 5 | 102 | 39 |
| 42 | 6 | 103 | 39 |
| 43 | 6 | 104 | 40 |
| 44 | 7 | 105 | 41 |
| 45 | 7 | 106 | 41 |
| 46 | 8 | 107 | 42 |
| 47 | 8 | 108 | 42 |
| 48 | 9 | 109 | 43 |
| 49 | 9 | 110 | 43 |
| 50 | 10 | 111 | 44 |
| 51 | 11 | 112 | 44 |
| 52 | 11 | 113 | 45 |
| 53 | 12 | 114 | 46 |
| 54 | 12 | 115 | 46 |
| 55 | 13 | 116 | 47 |
| 56 | 13 | 117 | 47 |
| 57 | 14 | 118 | 48 |
| 58 | 14 | 119 | 48 |
| 59 | 15 | 120 | 49 |
| 60 | 16 |
Values are rounded to the nearest whole degree. Note that a temperature difference converts differently: a 9F change equals a 5C change, with no offset.
The Temperatures That Decide Your Output
Three numbers govern most rating discussions. Gas turbines are rated at ISO conditions of 15C, or 59F. Reciprocating engines under ISO 3046 are referenced to 25C, or 77F. Generating sets are commonly rated at 40C ambient, or 104F.
Every degree above the reference costs output. For natural gas turbines the loss is typically 0.5 to 0.9 percent of rated power per degree Celsius above 15C, subject to the machine curve. At 45C in Mali or Iraq that decides whether a guarantee is met. Diesel and HFO generating sets derate more gently but still derate, and radiator sizing adequate at 25C will not be at 45C.
Frequently Asked Questions
What is the formula to convert Fahrenheit to Celsius?
C = 5/9 x (F minus 32). Subtract 32 first, then multiply by 5 and divide by 9. So 95F is 35C.
What is 104F in Celsius?
40C, the standard ambient rating point for most generating sets.
Why do power ratings quote 15C and 25C?
15C is the ISO reference for gas turbines, 25C the ISO 3046 reference for reciprocating engines. Output quoted there is a laboratory reference, not a site guarantee.
Site rated output is the only number worth contracting on. USP&E Global has delivered 150+ projects across 35+ countries in some of the hottest environments on earth, and our EPC construction teams derate against measured site conditions rather than nameplate. Climate and energy data by country is published by the International Energy Agency, the World Bank, and the African Development Bank.
Ready to Power Your Project? Talk to USP&E’s Engineers Free.
USP&E Global offers a complimentary 4-hour engineering consultation for qualified power station, EPC, and O&M projects. Whether you are in early feasibility or ready to mobilize, our team of 350+ engineers across 35+ countries is ready to guide your project to success with speed and without excuses.
USP&E Global. Powering Possibility. Built for the Frontier.
ISO 9001:2015 | ISO 45001:2018 | 150+ Projects | 35+ Countries | Zero Lawsuits