Question 1

How do I calculate distance between two GPS coordinates?

Accepted Answer

Use the Haversine formula: d = 2r x arcsin(sqrt(sin^2((lat2-lat1)/2) + cos(lat1) x cos(lat2) x sin^2((lon2-lon1)/2))), where r = 6,371km (Earth radius). This gives the great-circle (straight-line across the globe) distance. For driving distance, use a routing API like Google Maps.

Question 2

How do I convert decimal degrees to degrees minutes seconds?

Accepted Answer

Degrees = integer part of decimal degrees. Minutes = integer part of (decimal fraction x 60). Seconds = (remaining fraction x 60). For 51.5074N: degrees = 51, minutes = int(0.5074 x 60) = 30, seconds = 0.444 x 60 = 26.64. Result: 51 degrees 30 minutes 26.64 seconds N.

Question 3

What is the difference between WGS84 and UTM coordinates?

Accepted Answer

WGS84 (World Geodetic System 1984) uses latitude/longitude in decimal degrees referenced to the Earth's centre. UTM (Universal Transverse Mercator) uses metres in a flat grid projection divided into 60 zones. UTM is better for measuring distances and areas in a local area; WGS84 is the standard for GPS and global datasets.

Question 4

Are these GIS tools free?

Accepted Answer

Yes - completely free, no sign-up required. Results export to CSV or PDF.

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