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Temperature Conversions — °C to °F Reference
Celsius to Fahrenheit conversion formula and common UK plumbing, heating and construction temperature reference points.
Quick Conversion Table
| °C | °F | °C | °F |
|---|---|---|---|
| -10 | 14 | 50 | 122 |
| 0 | 32 | 55 | 131 |
| 5 | 41 | 60 | 140 |
| 10 | 50 | 65 | 149 |
| 15 | 59 | 70 | 158 |
| 20 | 68 | 75 | 167 |
| 25 | 77 | 80 | 176 |
| 30 | 86 | 90 | 194 |
| 37 | 98.6 | 100 | 212 |
| 40 | 104 | 120 | 248 |
UK Construction Temperature Reference Points
| Application | °C | °F | Reference |
|---|---|---|---|
| Frost protection (pipes) | 0 | 32 | Lagging, trace heating |
| Min temp for painting (exterior) | 5 | 41 | Most manufacturers |
| Min temp for concreting | 5 | 41 | BS 8500 |
| Room temperature (design) | 21 | 70 | Part L / CIBSE Guide A |
| Bathroom temperature (design) | 22 | 72 | CIBSE Guide A |
| Shower temperature | 38 – 41 | 100 – 106 | User preference |
| Max bath temperature (TMV) | 48 | 118 | Part G / NHS scalding prevention |
| DHW distribution minimum | 50 | 122 | HSE L8 / HSG274 |
| Legionella danger zone | 20 – 45 | 68 – 113 | HSE L8 |
| DHW storage minimum | 60 | 140 | HSE L8 / Part G |
| Heating flow (traditional) | 75 | 167 | Standard radiator design |
| Heating return (traditional) | 65 | 149 | 10°C DT |
| UFH flow temperature | 35 – 55 | 95 – 131 | BS EN 1264 |
| PVC cable max operating temp | 70 | 158 | BS 7671 |
Related Pages
See the Boiler Flue Temperature Ranges, the Pressure Unit Conversions, and the Part G Hot Water Standards.
Next up: related pages
Frequently Asked Questions
°F = (°C × 9/5) + 32. Or more simply: double the Celsius value and add 30 for a quick approximation. To convert back: °C = (°F - 32) × 5/9. Key reference points: 0°C = 32°F (freezing), 100°C = 212°F (boiling), 20°C = 68°F (room temperature), 37°C = 98.6°F (body temperature).
Hot water must be stored at a minimum of 60°C to prevent Legionella bacteria growth per HSE Approved Code of Practice L8 and HSG274. Legionella thrives between 20°C and 45°C and is killed above 60°C. The stored water temperature should be checked regularly. Distribution temperature should reach 50°C at outlets within 1 minute of running. Domestic hot water should not exceed 48°C at bath outlets (to prevent scalding, especially in homes with children or vulnerable people).
Traditional UK heating systems: flow temperature 75°C, return 65°C (10°C differential). Modern condensing boilers are more efficient at lower temperatures — weather compensation systems may use flow temperatures of 40-55°C. Underfloor heating typically operates at 35-55°C flow temperature. For a condensing boiler to condense efficiently, the return water temperature should be below 55°C (the dewpoint of flue gases for natural gas).
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Last updated: April 2026
Verified against UK standards · estimates only, confirm with your supplier.