🌡️ Temperature Converter
Freezing (0°C) Boiling (100°C) Body Temp (37°C) Room Temp (20°C) Absolute Zero
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Temperature Conversion Formulas Explained

Every temperature scale conversion reduces to a simple linear formula. Here's exactly how each one works.

Celsius ↔ Fahrenheit
°F = (°C × 9/5) + 32
°C → °F: multiply by 1.8, add 32
°F → °C: subtract 32, divide by 1.8
Celsius ↔ Kelvin
K = °C + 273.15
Kelvin has no negative values — 0 K is absolute zero.
Celsius ↔ Rankine
°R = (°C + 273.15) × 9/5
Rankine is Fahrenheit-sized degrees on an absolute-zero scale.
Celsius ↔ Réaumur
°Ré = °C × 4/5
Once common in Europe, still occasionally seen in older recipes and dairy/spirits industries.

Worked Example: 20°C to Fahrenheit

1
Multiply 20 by 9/5 (1.8): 20 × 1.8 = 36
2
Add 32: 36 + 32 = 68
✓ 20°C = 68°F · Reverse: (68 − 32) ÷ 1.8 = 20°C

Oven Temperature, Gas Mark & Air Fryer Conversion Guide

British recipes use Gas Mark, American recipes use Fahrenheit, and most of the world bakes in Celsius. Here's how they line up.

Gas MarkCelsiusFahrenheitOven Description
¼110°C225°FVery cool
½120°C250°FVery cool
1140°C275°FCool
2150°C300°FCool
3160°C325°FWarm
4180°C350°FModerate (most common)
5190°C375°FModerately hot
6200°C400°FHot
7220°C425°FHot
8230°C450°FVery hot
9240°C475°FVery hot

Fan / Convection Oven Adjustment

Fan-forced (convection) ovens circulate hot air and typically run about 20°C (35°F) hotter than a conventional oven at the same dial setting. If a recipe was written for a conventional oven and you're using a fan oven, lower the temperature by 20°C (35°F) — our Cooking mode above does this automatically.

Converting an Oven Recipe for an Air Fryer

Air fryers cook faster because a small fan circulates hot air tightly around the food. The general rule: reduce the oven temperature by about 25°F (roughly 15°C) and start checking for doneness 20-25% earlier than the original oven time.

Body Temperature & Fever Ranges by Age

General reference ranges for oral temperature readings. Actual clinical thresholds can vary by measurement method and individual baseline.

CategoryCelsiusFahrenheit
HypothermiaBelow 35.0°CBelow 95.0°F
Below normal35.0–36.0°C95.0–96.8°F
Normal range36.1–37.2°C97.0–99.0°F
Low-grade fever37.3–38.0°C99.1–100.4°F
Fever38.1–39.4°C100.5–103.0°F
High fever39.5–41.0°C103.1–105.8°F
Medical emergencyAbove 41.0°CAbove 105.8°F

Infants Under 3 Months Are Different

For babies under 3 months old, any rectal reading at or above 38.0°C (100.4°F) is generally treated as a reason to contact a clinician the same day, even if the baby otherwise seems well — this age group doesn't follow the general adult scale above.

Measurement Method Matters

Rectal and ear readings tend to run slightly higher than oral readings, while armpit readings tend to run slightly lower — often by around 0.3-0.5°C (0.5-1°F). Our Body & Fever mode factors this in when classifying a reading.

This information is for general reference only and is not medical advice. If you're concerned about a fever, a very low reading, or any other symptom, contact a doctor or healthcare provider.

Common Temperature Conversions

DescriptionCelsiusFahrenheitKelvin
Absolute zero-273.15°C-459.67°F0 K
Water freezes0°C32°F273.15 K
Room temperature20°C68°F293.15 K
Average body temperature37°C98.6°F310.15 K
Water boils (sea level)100°C212°F373.15 K
Moderate oven (Gas Mark 4)180°C356°F453.15 K

Temperature Converter — Frequently Asked Questions

Common questions about scale conversions, oven/gas mark settings, and body temperature readings.