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Reference

Key Temperatures to Know: Freezing, Boiling, Body, and Oven

Gizmoop Team · 5 min read · May 22, 2026

Here are the 15 temperatures everyone should know, in both Celsius and Fahrenheit. Memorize these reference points and you can interpret any weather report, oven setting, body temperature, or recipe, anywhere in the world. The pairs anchor your mental temperature scale.

Master reference table

Phenomenon°C°FContext
Absolute zero-273.15-459.67Lowest possible temperature
Dry ice sublimes-78-109Solid CO2 turns to gas
Coldest natural temp on Earth-89.2-128.6Vostok, Antarctica, 1983
Typical freezer-180Domestic freezer setting
Water freezes032Phase change at sea level
Refrigerator439Safe food storage
Cool day1050Light jacket weather
Room temperature20-2268-72Comfortable indoor
Warm day2577T-shirt weather
Hot day3086Sweating weather
Body temperature3798.6Normal healthy adult
Fever threshold38100.4Officially a fever
Very hot day40104Heat warning territory
Hot tap water49-60120-140Can scald in seconds
Sauna80-100176-212Tolerable in dry heat only
Water boils100212At sea level
Moderate oven165325Custards, delicate baking
Hot oven175350Cookies, cakes, casseroles
Very hot oven230450Pizza, roasting, broiling
Aluminum melts6601220Useful for industry context
Iron melts15382800Forging and casting steel

The temperatures that anchor everything

If you only memorize five: water freezes (0°C / 32°F), room temperature (20°C / 68°F), body temperature (37°C / 98.6°F), water boils (100°C / 212°F), and oven baking (175°C / 350°F). These five let you reason about any other temperature you encounter.

For weather: 20°C (68°F) is "shirt-sleeves comfortable", 30°C (86°F) is "uncomfortably hot", 10°C (50°F) is "jacket weather", 0°C (32°F) is "freezing". For health: 37°C is normal body temperature, 38°C is a fever, 40°C is dangerous. For cooking: 100°C boils water, 175°C bakes most things, 230°C roasts and chars.

The conversion shortcut

Mental math from Celsius to Fahrenheit: double and add 30. So 25°C × 2 + 30 = 80°F (close to the exact 77°F). For Fahrenheit to Celsius: subtract 30 and halve. So 80°F − 30 = 50, ÷ 2 = 25°C (close to exact 26.7°C). The shortcut is off by a few degrees at temperature extremes; for everyday weather it works fine. For precision, multiply by 1.8 and add 32.

Why these references matter

Knowing key temperatures changes how you read information. A weather forecast of 35°C means nothing if you only think in Fahrenheit; knowing it equals 95°F (hot day) makes it actionable. A fever of 102°F means little to someone raised in Celsius; knowing it equals 39°C (high fever, see a doctor) makes it actionable. Cross-cultural medicine, travel, and science all require fluency with both scales.

Frequently asked questions

Water freezes at 0°C (32°F) and boils at 100°C (212°F) at standard atmospheric pressure (sea level). These are the two reference points for the Celsius scale and are exactly 180°F or 100°C apart. At higher elevations water boils at lower temperatures: in Denver (1,600 m altitude) water boils at about 95°C (203°F).

37°C (98.6°F) is the historical average, but the modern healthy range is 36.1-37.2°C (97-99°F). Body temperature varies through the day (lower in the morning, higher in the evening), with menstrual cycle, and after exercise. A 2020 study suggested average body temperature has dropped slightly since the 1860s, possibly because of better healthcare reducing chronic inflammation.

Above 38°C (100.4°F) is officially a fever in adults. 37.5-38°C (99.5-100.4°F) is a low-grade fever. Above 39°C (102.2°F) is a high fever; above 40°C (104°F) is dangerous and warrants medical attention. For children, fever thresholds are slightly lower (37.5°C is sometimes flagged).

Hot oven (350°F / 175°C, gas mark 4) is the most common baking temperature for cookies, cakes, and casseroles. Very hot oven (450°F / 230°C, gas mark 8) is used for roasting and pizza. Moderate oven (325°F / 165°C, gas mark 3) is for delicate baking like custards. Low oven (250-300°F / 120-150°C, gas mark 1-2) is for slow roasts and dehydrating.

20-22°C (68-72°F) is the typical comfortable indoor range. Thermostat settings vary by season and personal preference. Engineers often use 25°C (77°F) as "standard room temperature" for technical specifications. Heating and cooling systems are typically designed around this range.

Iron melts at 1538°C (2800°F). Steel ranges 1370-1500°C depending on alloy. Aluminum melts at 660°C (1220°F). Copper melts at 1085°C (1985°F). Tungsten melts at 3422°C (6192°F), the highest of any metal. A hot kitchen oven (260°C, 500°F) is nowhere near melting any common metal.

Naturally: -89.2°C (-128.6°F) at Vostok Station, Antarctica, in 1983. In laboratories: temperatures within a billionth of a degree of absolute zero (-273.15°C / -459.67°F) have been achieved using laser cooling. Absolute zero itself is impossible to reach, the third law of thermodynamics says you can get arbitrarily close but never exactly there.

Above 35°C (95°F) starts to feel uncomfortably hot. Above 40°C (104°F) is dangerous for prolonged exposure (heat stroke risk). Tactile threshold for pain on skin: about 45°C (113°F). Hot tap water in the US is typically 49-60°C (120-140°F) and can cause burns within seconds. Saunas run 80-100°C (176-212°F), tolerable only because of low humidity.