Enter the stellar radius and the star-planet distance into the Calculator. The calculator will evaluate the Transit Probability. 

Transit Probability Formula

Tp = R/a


  • Tp is the Transit Probability ()
  • R is the stellar radius
  • a is the star-planet distance

To calculate Transit Probability, divide the stellar radius by the star-to-planet distance.

How to Calculate Transit Probability?

The following steps outline how to calculate the Transit Probability.

  1. First, determine the stellar radius. 
  2. Next, determine the star-planet distance. 
  3. Next, gather the formula from above = Tp = R/a.
  4. Finally, calculate the Transit Probability.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

stellar radius = 5000

star-planet distance = 123000