Temperature Converter
Celsius, Fahrenheit and Kelvin, with site temperature references.
Inputs
Result
Formula
| Celsius to Fahrenheit | °F = °C × 1.8 + 32 |
| Fahrenheit to Celsius | °C = (°F − 32) ÷ 1.8 |
| Celsius to Kelvin | K = °C + 273.15 |
| Kelvin to Celsius | °C = K − 273.15 |
| Rankine | °R = (°C + 273.15) × 1.8 |
| Intervals | Δ1°C = Δ1.8°F — only differences scale |
20°C is 68°F, 293.15 K or 527.67 °R. At 5°C concrete cures normally; at −2°C it needs insulating or heating, or the early frost damage permanently reduces strength.
Temperatures that matter on site
| Temperature | Situation | Requirement |
|---|---|---|
| 0°C | Freezing point | Water freezes; concrete needs frost protection |
| 5°C | Winter concreting | Winter rules apply below 5°C for five consecutive days |
| 10°C | Asphalt placement | Not normally placed below 10°C |
| 20°C | Cube curing | Standard curing at 20 ± 2°C |
| 60°C | Steam curing cap | Usually not above 60°C to avoid strength regression |
| 100°C | Boiling point | Water boils at atmospheric pressure |
FAQ
Why can't Celsius be doubled to get Fahrenheit?
Because the zeros differ: 0°C is 32°F, not 0°F, so the offset must be applied before scaling. The “double and add 30” shortcut is only a rough estimate — 2°C out near 20°C but 12°C out near 100°C, useless for measuring asphalt or concrete temperature.
What temperature triggers winter concreting rules?
Winter rules apply when the daily mean stays below 5°C for five consecutive days. Then thermal blankets, heated enclosures or antifreeze admixtures are required, with placing temperature not below 5°C (2°C for mass concrete). The earlier and colder the freeze, the greater and more permanent the strength loss.
Kelvin and Celsius differ by a constant, so why keep both?
Kelvin starts at absolute zero, which physics formulas such as the ideal gas law and radiation laws require, otherwise negatives break the equations. Celsius puts zero at the freezing point of water, which suits daily use, and site work, material standards and codes all use it. The conversion is simply 273.15.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.