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Pendulum period calculator

How long a simple pendulum takes to swing back and forth, from its length.

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Period (there and back) 2.006 s

How it works

T = 2π √(L ÷ g)

For small swings (under about 15°), a pendulum’s period depends only on its length and gravity, not on its weight or how far it swings. That regularity is why pendulums ran clocks for 300 years: a 99.4 cm pendulum ticks once a second each way. Four times the length doubles the period.

  1. 2π times the square root of L ÷ g 2π × √(1 ÷ 9.80665) = 2.006 s

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