Planetary Transit Calculator

Calculate transit depth, duration, probability, and timing for exoplanet transits.

Star Radius

Solar Radii

Planet Radius

Earth Radii

Orbital Period

days

Semi-Major Axis

Orbital Inclination

degrees

Tab to move between fields

Transit Depth

0.000001

Transit Duration

12.98 hours

Transit Probability

0.00465%

Impact Parameter0

Ingress Duration0.0005 days

Orbital Velocity29,785.68 m/s

How to Use This Calculator

Enter Star Radius (solar radii) and Planet Radius (Earth radii) for the target system.
Enter Orbital Period (days) and Semi-Major Axis (AU) — use Kepler's law if only one is known.
Set Orbital Inclination (°): 90° is perfectly edge-on; values below 90° reduce transit probability.
Read Transit Depth (fraction of stellar flux dimming) — a 1% dip means the planet covers 1% of the star's disk.
Use Transit Duration (hours) to plan observation windows and Transit Probability to assess detection likelihood.

What each input means

Transit Depth = (R_planet / R_star)²

Identify Input Parameters
4 parameters
Star Radius = 1, Planet Radius = 0.1, Orbital Period = 365.25, Semi-Major Axis = 1 = 5 input(s) provided
Calculate Transit Depth
Transit Depth
0.000001 = 0.000001
Calculate Transit Duration
Transit Duration
12.98 = 12.98
Calculate Transit Probability
Transit Probability
0.00465 = 0.00465%
Calculate Impact Parameter
Impact Parameter
0 = 0
Calculate Ingress Duration
Ingress Duration
0.0005 = 0.0005