How is orbital period calculated?

Using Kepler's Third Law relating period squared to the semi-major axis cubed.

Does orbital period depend on the orbiting object's mass?

No — for small orbiting bodies, it depends almost entirely on distance and the central body's mass.

Why do outer planets take longer to orbit?

They're much farther away, and period increases with distance per Kepler's law.

Orbital Period Calculator - CalculatorLabs.net

Orbital Period Calculator

An object's orbital period is the time it takes to complete one full trip around the body it orbits.

Semi-Major Axis a (m)

Central Mass M (kg)

Instant Result

Orbital Period (seconds) -

Orbital Period (days) -

What Is a Orbital Period Calculator?

An object's orbital period is the time it takes to complete one full trip around the body it orbits. Kepler's Third Law connects that period to the size of the orbit (semi-major axis) and the mass being orbited.

How to Use This Orbital Period Calculator

Enter the orbit's semi-major axis in meters (the average distance from the central body).
Enter the mass of the central body being orbited, in kilograms.
Click Calculate to get the orbital period in seconds and days.

Formula

Orbital Period T = 2π × √(a³ / GM)
G = 6.674 × 10⁻¹¹ N·m²/kg²

Worked Example

The Moon orbits Earth (M = 5.97×10²⁴ kg) at a = 3.84×10⁸ m. T = 2π√((3.84×10⁸)³ / (6.674×10⁻¹¹ × 5.97×10²⁴)) ≈ 2,373,000 s ≈ 27.5 days — matching the Moon's real orbital period.