Temperature Compare

[Please note first]

This app cannot tell you how hot anything is. Phones have no air-temperature

hardware inside them. You type in a figure you already know, and it is lined up

against everyday things. It does not fetch local weather or a forecast, and it

gives no health, medical or food-safety advice.

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Temperature Compare — how hot is that, really?

"45 °C" on its own does not tell you much. A hot bath is 42 to 43 °C,

so it is a little above that. "Magma is 700 to 1,200 °C" gets closer

once you know that gold melts at 1,064 °C.

Type in one figure and 33 things line up around it, from absolute zero

to the surface of the Sun.

■ Switch between °C, °F and K

Three buttons at the top change the input and the whole list at once.

Type in the Fahrenheit figure you saw in an article, or work in kelvin

the way a physics class does.

0 °C = 32 °F = 273.15 K

Minus forty is the one point where the two scales meet: −40 °C = −40 °F.

Changing the unit never changes the order. Only the numbers look different.

■ Thirty-three things

Absolute zero (−273.15 °C), cosmic background radiation, liquid nitrogen

boiling, night on the Moon, the coldest reading ever taken in Antarctica,

dry ice turning to gas, Mars on average, the coldest reading in Japan,

mercury freezing, a home freezer, water freezing (0 °C), a home fridge,

chocolate melting, butter melting, the human body, a warm bath, the

hottest reading in Japan, a hot bath, the hottest air ever recorded,

inside a sauna, water boiling (100 °C), day on the Moon, deep-frying oil,

lead-free solder melting, lead melting, the surface of Venus, aluminum

melting, magma, gold melting, a candle flame, iron melting, tungsten

melting (3,422 °C) and the surface of the Sun (5,500 °C).

Tap any row to load its figure.

■ Temperature is compared by difference

20 °C is not "four times as warm" as 5 °C. Zero does not mean "no heat" —

it is simply where water freezes — so dividing one temperature by another

tells you nothing.

When this app sorts by nearness it looks at the difference, not the ratio.

That is the one thing it does differently from an app about weight or length.

■ Ranges are shown as ranges

A home fridge is 3 to 5 °C, the human body 36 to 37 °C, a hot bath 42 to 43 °C.

Anything that varies with use is given a range alongside its typical figure.

The range is shown only for reading; the comparison always uses the single

typical figure.

■ Nothing below absolute zero

There is no temperature below −273.15 °C, because that is the point where

nothing can get any colder. Type in something lower and the app explains

that instead of answering.

■ Good for

▪ Making sense of a figure in the news or in a recipe

▪ Turning a Fahrenheit figure from an article into something familiar

▪ Explaining heat to a child

▪ Attaching a real feeling to a number from a science lesson

■ Things worth knowing (included in the app)

▪ −273.15 °C is absolute zero. Temperature has a floor beneath it

▪ 20 °C is not four times 5 °C, because zero does not mean "no heat"

▪ Japan's records, from the Japan Meteorological Agency: 41.1 °C (Hamamatsu

2020, Kumagaya 2018) and −41 °C (Asahikawa 1902)

▪ World records: 56.7 °C (Death Valley 1913) and −89.2 °C (Antarctica 1983)

▪ Mercury is liquid at −38.8 °C; tungsten stays solid to 3,422 °C

▪ A Japanese bath runs 38 to 43 °C — hotter than a typical Western bathtub

■ How the app is built

▪ A single screen. No settings page, no tabs to hunt through

▪ Your last five entries are kept and can be tapped to restore

▪ Japanese and English, following your device language

▪ No account needed. The comparison runs on your device and your figures are never sent anywhere

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Note: figures given as a range are typical guides; a home fridge, a bath or

frying oil all vary with how they are used. This app has no way of telling

how hot anything actually is, and offers no health, medical or food-safety

advice.