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About this tool
Convert degrees Fahrenheit to degrees Celsius instantly. Free, bidirectional, and fully in-browser.
Convert degrees Fahrenheit to degrees Celsius with the formula °C = °F × 0.555556 − 17.777778 — type any temperature to see the result at once. This Fahrenheit to Celsius converter is a client-side tool: it applies the exact temperature formula (°C = °F × 0.555556 − 17.777778) in your browser, updates the moment you type, and works in both directions — edit either field, or press swap, to convert degrees Celsius back to degrees Fahrenheit. A reference table lists common fahrenheit values already converted, and nothing you enter is sent to a server.
Open Fahrenheit to Celsius Converter on AltFTool — it loads instantly in your browser.
Type the value you want to convert into the Fahrenheit field.
Read the equivalent in degrees Celsius in the result field, and copy it if needed.
Use the decimal-places slider for more or less precision, or press swap to convert degrees Celsius to degrees Fahrenheit.
The result updates as you type, and the swap button flips the conversion to celsius → fahrenheit without reloading.
The conversion uses the exact formula °C = °F × 0.555556 − 17.777778, so the number matches a manual calculation to the decimal places you choose.
A slider sets 0–10 decimal places, and very small or very large results switch to scientific notation instead of rounding to zero.
Everything runs locally in your browser — no upload, no account, no limit on conversions.
Use the formula °C = °F × 0.555556 − 17.777778. For example, 25 °F = -3.8889 °C.
°C = °F × 0.555556 − 17.777778. This tool applies it automatically and shows a worked example: 25 °F = -3.8889 °C.
Yes. Press the swap button, or type into the celsius field, and the tool converts degrees Celsius to degrees Fahrenheit using the inverse of the same relationship.
It uses the standard temperature definition, not a rounded approximation, so results are exact to the number of decimal places you select.
Yes. The converter is a browser-side script with no network calls: your values are never uploaded, and once the page has loaded it keeps working without a connection.
Add the Fahrenheit to Celsius Converter widget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
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