21zoo Labs - Assorted Stuff

How to Calculate the Distance Between Two Lat,Long Points in Golang

Posted at — Jun 7, 2019

This will return the distance between two points in miles. To get the distance in kilometers, multiply with 1.60934.

func distance(lat1 float64, lng1 float64, lat2 float64, lng2 float64) float64 {
	radlat1 := float64(math.Pi * lat1 / 180)
	radlat2 := float64(math.Pi * lat2 / 180)

	theta := float64(lng1 - lng2)
	radtheta := float64(math.Pi * theta / 180)

	dist := math.Sin(radlat1)*math.Sin(radlat2) + math.Cos(radlat1)*math.Cos(radlat2)*math.Cos(radtheta)

	if dist > 1 {
		dist = 1
	}

	dist = math.Acos(dist)
	dist = dist * 180 / math.Pi
	dist = dist * 60 * 1.1515

	return dist
}