DMS Converter

Understanding the "DMS" System

In the modern world, we are used to seeing decimals everywhere. If you check Google Maps, you might see a coordinate like 40.7128° N. This is known as the "Decimal Degree" format.

However, historically (and in many scientific fields today), angles and geographic coordinates are broken down using the Sexagesimal System. This system divides circles and spheres into:

• Degrees (°): The largest unit. There are 360° in a full circle.
• Minutes ('): Each degree is divided into 60 minutes.
• Seconds ("): Each minute is divided into 60 seconds.

This is why it is called the "DMS" (Degree-Minute-Second) system. It functions exactly like a clock, where 1 hour = 60 minutes, but applied to geometry.

Why do we still use DMS?

You might wonder, why not just use decimals for everything? While computers prefer decimals, the DMS system is still standard in:

• Astronomy: Locating stars using Right Ascension and Declination.
• Navigation: Maritime and Aviation charts still rely heavily on Minutes and Seconds.
• Land Surveying: Legal boundaries of property lines are often defined in DMS.

The Conversion Math Formula

Our DMS calculator above handles the heavy lifting instantly, but it is always good to know the math behind the magic. Converting DMS to Decimal Degrees involves simple division.

Formula: DMS to Decimal

$$Decimal = Degrees + \frac{Minutes}{60} + \frac{Seconds}{3600}$$

Formula: Decimal to DMS

Going the other way is slightly trickier because you have to isolate the remainders.

• Degrees: Take the whole number part (Integer).
• Minutes: Multiply the decimal remainder by 60. Take the whole number part.
• Seconds: Multiply the new remainder by 60.

Accuracy in GPS Coordinates

When working with GPS and Mapping, precision matters. In the Decimal system, the number of digits after the dot determines your accuracy on the ground. This is why converting correctly is crucial.

If you are inputting coordinates into a drone or hiking GPS, simply rounding off the last few decimals can put you hundreds of meters off course!