Every point on Earth's surface can be written two common ways: Degrees-Minutes-Seconds
(DMS), like 26° 54' 44.6" N, or Decimal Degrees (DD), like 26.9124°.
They describe the exact same location — the difference is purely notation, inherited from
how latitude and longitude were originally measured with a sextant, in a system borrowed
from how we divide an hour into minutes and seconds.
How the conversion actually works
A degree splits into 60 minutes, and each minute splits into 60 seconds — the same structure as time. To get Decimal Degrees from DMS:
So 26° 54' 44.6" becomes 26 + (54/60) + (44.6/3600) = 26.9124°.
Going the other direction, the whole-number part of the decimal value is the degrees; the
remaining fraction, multiplied by 60, gives the minutes; and the fraction of that,
multiplied by 60 again, gives the seconds.
Where this quietly goes wrong
- Dropping the hemisphere. A coordinate without N/S or E/W (or without a correctly applied negative sign for S/W) can end up on the wrong side of the equator or prime meridian entirely — the numbers look right, the location is wrong.
- Treating minutes/seconds as base-10. They're base-60. Averaging
26° 30'and26° 45'is not26° 37.5'by simply averaging the raw numbers if seconds are involved — the carrying between units has to be handled correctly. - Copy-paste symbol corruption. The degree symbol, prime ('), and double-prime (") often get mangled when copying coordinates out of a PDF or a website — turning into straight quotes, question marks, or disappearing entirely, which then fails to parse correctly downstream.
When you'd use each format
Decimal Degrees is what almost all modern software — GIS tools, GPS devices, mapping APIs — expects internally. DMS is still common on printed survey documents, older government records, and some legal/cadastral descriptions. Converting between them is usually the first step in getting older coordinate data into a modern workflow.
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