Planck time
Planck time is the theoretical shortest meaningful interval of time, defined using fundamental physical constants.
How big is it?
5.391 × 10⁻⁴⁴ s
Time · theoretical
A little perspective
About the same scale as Planck length.
Planck length: The Planck length is a scale formed from fundamental physical constants.
Measurements, assumptions & sources +
Planck time
A theoretical scale, not an experimentally demonstrated smallest time step.
NIST — 2022 CODATA fundamental constants
The marked time is calibrated. Unmeasured illustration details are representative.
Planck length
A theoretical scale formed from the speed of light, reduced Planck constant and gravitational constant. It is not experimentally established as the smallest possible length. The area and volume are derived mathematical scales.
NIST — 2022 CODATA fundamental constants
The marked time is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 5.391 × 10⁻⁴⁴ s
For comparison, this page uses time. This is a theoretical scale, not a measured hard boundary or proof of a physical limit.
A theoretical scale, not an experimentally demonstrated smallest time step.
The identifying illustration and the numerical comparison remain separate. How calibrated comparisons work →
Recorded properties
Planck time dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 5.391 × 10⁻⁴⁴ s | Not recorded | theoretical |
Around this scale
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These links use compatible time records, ordered around the selected value.
Sources and method
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The source records and measurement method remain available for inspection.
- NIST — 2022 CODATA fundamental constantsRecommended constants with uncertainties; exact SI definitions are distinguished from measured constants.
More ways to see it
Curated comparisons
There’s always another scale
Follow your curiosity.
TimeBlink of an eye150 msA blink of an eye is the quick closing and opening of the eyelid, usually happening involuntarily.TimeHuman lifetime80 yearsA human lifetime is the span from a person's birth to their death.
TimeAge of Earth4.54 GyrThe age of Earth is the time that has passed since the planet formed from the solar nebula.TimeAge of the universe13.8 GyrThe age of the universe is the time since the Big Bang, marking the beginning of cosmic expansion.
Fundamental physicsPlanck length1.616 × 10⁻³⁵ mThe Planck length is a scale formed from fundamental physical constants.
TimeTop quark lifetime5 × 10⁻²⁵ sThis is the average time a top quark exists before it decays into other particles.TimeAtomic-scale transition1 fsAn atomic-scale transition is a rapid change in the energy state of an atom, often occurring in extremely short intervals.Fundamental physicsCaesium-133 clock transition108.8 psThe caesium-133 clock transition is the specific change in energy state of a caesium-133 atom that defines the duration of one second in the International System of Units.