Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Horizon Distance Calculator

Calculate the maximum distance at which an observer can see a target object over the horizon, based on both their heights above sea level. Ideal for navigation, broadcasting tower placement, and outdoor planning.

Observer Height (m)

Target Height (m)

Fill in the required fields to see your result.

Geography

Earthquake Distance Calculator

Estimate the distance from a seismograph station to an earthquake epicenter using the arrival time difference between P and S seismic waves. Useful for seismology education and rapid preliminary epicenter location.

P Wave Arrival Time (seconds)

S Wave Arrival Time (seconds)

Fill in the required fields to see your result.

Key differences

	Horizon Distance Calculator	Earthquake Distance Calculator
Category	Geography	Geography
Inputs required	2	2
Result	Visibility Distance (km)	Epicenter Distance (km)
What it does	Calculate the maximum distance at which an observer can see a target object over the horizon, based on both their heights above sea level. Ideal for navigation, broadcasting tower placement, and outdoor planning.	Estimate the distance from a seismograph station to an earthquake epicenter using the arrival time difference between P and S seismic waves. Useful for seismology education and rapid preliminary epicenter location.