Seconds Pendulum (Period = 2 s, Length ≈ 0.994 m)
A seconds pendulum requires a length of approximately 0.994 m to achieve exactly a 2-second period on Earth.
How to use this tool
- Enter pendulum length l, gravity g and amplitude θ in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your period (small-angle approx.) and the full breakdown beneath it.
The 'seconds pendulum' with a 2-second period (1 second per half-swing) was historically used to define the metre.
Frequently asked questions
- What is the period of a 1-metre pendulum on Earth?
- Approximately 2.006 seconds, which is why 1-metre pendulums were historically used in grandfather clocks (half-period ≈ 1 s per swing).
- Does mass affect the period?
- No — the small-angle period T = 2π√(L/g) is entirely independent of mass.