Orders of magnitude (time)

An order of magnitude describes the link between two amounts. The difference between each step is usually 10, with each order being either 10 times greater or 10 times smaller than the next amount. This makes the scale easy to manipulate using logarithms. For time, the difference between the smallest limit of time, the Planck time, and the next order of magnitude is larger than 10.

Seconds

Orders of magnitude (time)

Factor (s)	Multiple	Symbol	Definition	Comparative examples & common units	Orders of magnitude
10−44		tP	Planck time is the unit of time of the natural units system known as Planck units.	The shortest length of time that can be described by physics. ≈ 5.4×10−44 s. (≈ meaning about)	10−44 s
10−24	1 yoctosecond	ys	Yoctosecond, (yocto + second), is one quadrillionth (in the long scale) or one septillionth (in the short scale) of a second.	0.3 ys: mean life of the W and Z bosons. 1 ys: time for top quark decay. 1 ys: time taken for a quark to emit a gluon. 91 ys: half-life of lithium-4.	1 ys and less, 10 ys, 100 ys
10−21	1 zeptosecond	zs	Zeptosecond, (zepto + second), is one trillionth of one billionth of one second.	7 zs: half-life of helium-9's outer neutron in the second nuclear halo. 17 zs: approximate period of electromagnetic radiation at the boundary between gamma rays and X-rays. 300 zs: approximate typical cycle time of X-rays, on the boundary between hard and soft X-rays	1 zs, 10 zs, 100 zs
10−18	1 attosecond	as	Attosecond is one quintillionth of a second	100 attoseconds: shortest measured period of time.	1 as, 10 as, 100 as
10−15	1 femtosecond	fs	Femtosecond is one quadrillionth of a second.	cycle time for 390 nanometre light, transition from visible light to ultraviolet	1 fs, 10 fs, 100 fs
10−12	1 picosecond	ps	Picosecond is one trillionth of a second.	1 ps: half-life of a bottom quark 4 ps: Time to execute one machine cycle by an IBM Silicon-Germanium transistor (supercomputer)	1 ps, 10 ps, 100 ps
10−9	1 nanosecond	ns	Nanosecond is one billionth of a second.	1 ns: Time to execute one machine cycle by an Intel Pentium 4 1 GHz microprocessor 1 ns: Light travels 12 inches (30 cm) 1,000,000,000 nanoseconds: 1 second	1 ns, 10 ns, 100 ns
10−6	1 microsecond	µs	Microsecond is one millionth of a second.	sometimes also abbreviated µsec 1 µs: Time to execute one machine cycle by an Intel 80186 microprocessor 4-16 µs: Time to execute one machine cycle by an older minicomputer	1 µs, 10 µs, 100 µs
10−3	1 millisecond	ms	Millisecond is one thousandth of a second.	50-80 ms: The time taken to blink an eye	1 ms, 10 ms, 100 ms
10−2	1 centisecond	cs	Centisecond is one hundredth of a second.
100	1 second	s		1 s: "One Mississippi" said aloud 60 s: 1 minute	1 s, 10 s, 100 s
103	1 kilosecond (16.7 minutes)	ks		3.6 ks: 3600 s or 1 hour 86.4 ks: 86 400 s or 1 day 604.8 ks: 1 week	103 s, 104 s, 105 s
106	1 megasecond (11.6 days)	Ms		month = 2.6 x 106 s year = 31.6 Ms = 107.50 s ≈ π x 107 s	106 s, 107 s, 108 s
109	1 gigasecond (32 years)	Gs		century = 3.16 Gs ≈ π×109 s millennium = 31.6 Gs ≈ π×1010 s	109 s, 1010 s, 1011 s
1012	1 terasecond (32 000 years)	Ts		eon = 31.6 Ts ≈ π×1013 s	1012 s, 1013 s, 1014 s
1015	1 petasecond (32 million years)	Ps		aeon = 31.6 Ps ≈ π×1016 s 435 Ps = 4.35×1017 s ≈ 13.8 billion years, the approximate age of the Universe	1015 s, 1016 s, 1017 s
1018	1 exasecond (32 billion years)	Es		0.43 Es ≈ the best estimate of the age of the Universe	1018 s, 1019 s, 1020 s
1021	1 zettasecond (32 trillion years)	Zs			1021 s, 1022 s, 1023 s
1024	1 yottasecond (32 quadrillion years)	Ys			1024 s, 1025 s, 1026 s and more

Years

Orders of magnitude (time)

Factor (a)	Multiple	common units	orders of magnitude
10−50		Planck time, the shortest physically meaningful interval of time ≈ 1.71×10−50 a	10−50 a
10−24	1 yoctoannum	--	1 ya and less, 10 ya, 100 ya
10−21	1 zeptoannum	--	1 za, 10 za, 100 za
10−18	1 attoannum	--	1 aa, 10 aa, 100 aa
10−15	1 femtoannum	--	1 fa, 10 fa, 100 fa
10−12	1 picoannum	--	1 pa, 10 pa, 100 pa
10−9	1 nanoannum	1 second = 3.17 × 10−8 a ≈ 10-7.50 a	1 na, 10 na, 100 na
10−6	1 microannum	1 minute = 1.90 × 10−6 a 1 hour = 1.40 × 10−4 a	1 ua, 10 ua, 100 ua
10−3	1 milliannum	1 day = 2.73 × 10−3 a 1 week = 1.91 × 10−2 a	1 ma, 10 ma, 100 ma
100	1 annum	year = 1 annum decade = 10 anna century = 100 anna	1 a, 10 a, 100 a
103	1 kiloannum	millennium = 1000 anna	103 a, 104 a, 105 a
106	1 megaannum	epoch = 1,000,000 anna	106 a, 107 a, 108 a
109	1 gigaannum	aeon = 1,000,000,000 anna 13.7 Ga = 1.37×1010 a ≈ 13.7 billion years, the approximate age of the Universe	109 a, 1010 a, 1011 a
1012	1 teraannum	---	1012 a, 1013 a, 1014 a
1015	1 petaannum	---	1015 a, 1016 a, 1017 a
1018	1 exaannum	--	1018 a, 1019 a, 1020 a
1021	1 zettaannum	--	1021 a, 1022 a, 1023 a
1024	1 yottaannum	--	1024 a, 1025 a, 1026 and more