Orders of magnitude

An order of magnitude is a difference between two numbers equal to multiplying one of them by ten. Orders of magnitude are quite easily and commonly described through the use of scientific notation and powers of ten.

One way of categorising things in the physical world is by their size. The pages below contain lists of items that are of the same order of magnitude in length, area, volume, or mass. This is useful for getting an intuitive sense of the comparative size of things and the overall scale of the universe.

In the following table the different quantities are lined up so that the following are in the same row: length and the time taken by light to cross that length, area of a square and the length of one side, volume of a cubes and the area of one face, mass of some water and its volume.

Time	Length	Area	Volume	Mass	Energy
10-44 s	10-35 m
...
10-28 s	10-19 m
10-27 s	10-18 m
10-26 s	10-17 m
10-25 s	10-16 m
10-24 s	10-15 m
10-23 s	10-14 m
10-22 s	10-13 m
10-21 s	10-12 m			10-33 kg 10-32 kg 10-31 kg	1000 eV 104 eV 105 eV
10-20 s	10-11 m			10-30 kg 10-29 kg 10-28 kg	1 MeV 10 MeV 100 MeV
10-19 s	0.1 nm	10-20 m2 10-19 m2		10-27 kg 10-26 kg 10-25 kg
10-18 s	1 nm	10-18 m2 10-17 m2		10-24 kg 10-23 kg 10-22 kg
10-17 s	10 nm	10-16 m2 10-15 m2		10-21 kg 10-20 kg 10-19 kg
10-16 s	100 nm	10-14 m2 10-13 m2	10-21 m3 10-20 m3 10-19 m3	10-18 kg 10-17 kg 10-16 kg	0.1 J 1 J 10 J
1 fs	1 μm	10-12 m2 10-11 m2	10-18 m3 10-17 m3 10-16 m3	10-15 kg 10-14 kg 10-13 kg	100 J 1000 J 104 J
10 fs	10 μm	10-10 m2 10-9 m2	10-15 m3 10-14 m3 10-13 m3	10-12 kg 10-11 kg 10-10 kg
100 fs	100 μm	10-8 m2 10-7 m2	10-12 m3 10-11 m3 10-10 m3	10-9 kg 10-8 kg 10-7 kg
1 ps	1 mm	10-6 m2 10-5 m2	10-9 m3 10-8 m3 10-7 m3	10-6 kg 10-5 kg 10-4 kg
10 ps	1 cm	1 cm2 10 cm2	1 ml 10 ml 100 ml	1 g 10 g 100 g
100 ps	100 cm	0.01 m2 0.1 m2	1 l 10 l 100 l	1 kg 10 kg 100 kg
1 ns	1 m	1 m2 10 m2	1 m3 10 m3 100 m3	1 t 10 t 100 t
10 ns	10 m	100 m2 1,000 m2	1,000 m3 10,000 m3 105 m3	106 kg 107 kg 108 kg
100 ns	100 m	1 ha 10 ha	106 m3 107 m3 108 m3	109 kg 1010 kg 1011 kg
1 μs	1 km	1 km2 10 km2	1 km3 10 km3 100 km3	1012 kg 1013 kg 1014 kg
10 μs	10 km	108 m2 109 m2	1012 m3 1013 m3 1014 m3	1015 kg 1016 kg 1017 kg
100 μs	100 km	1010 m2 1011 m2	1015 m3 1016 m3 1017 m3	1018 kg 1019 kg 1020 kg
1 ms	1000 km	1012 m2 1013 m2	1018 m3 1019 m3 1020 m3
10 ms	104 km	1014 m2 1015 m2
100 ms	105 km	1016 m2 1017 m2
1 s	106 km	1018 m2 1019 m2
10 s	107 km	1020 m2 1021 m2
100 s	1 AU
1 hr	10 AU
10 hr	100 AU
1 day	1000 AU
10 day	104 AU
1 yr	1 LY
10 yr	10 LY
100 yr	100 LY
1000 yr	1000 LY
104 yr	104 LY
105 yr	105 LY
106 yr	106 LY
107 yr	107 LY
108 yr	108 LY
109 yr	109 LY
1010 yr	1010 LY
...
1031 yr

Units used in the table:

• Time: femtosecond (fs), nanosecond (ns), microsecond, (μs), millisecond (ms), second (m), hour (hr), day (dy), year (yr)
• Length: nanometre (nm), micrometre (μm), millimetre (mm), centimetre (cm), metre (m), kilometre (km), astronomical unit (AU), light year (LY)
• Area: square metre (m²), hectare (ha), square kilometre (km²)
• Mass: gram (g), kilogram (kg), tonne (t)
• Volume: millilitre (ml), litre (l), cubic metre (m³)
• Energy: electronvolt (eV), Joule (J)

See also: SI units, SI prefix, conversion of units

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