How to Convert GPS Coordinates

Q: How do I convert decimal degrees to DMS manually?

Take the decimal degrees value, for example 40.7128. The whole number part (40) is the degrees. Multiply the decimal part (0.7128) by 60 to get minutes: 0.7128 × 60 = 42.768. The whole number (42) is the minutes. Multiply the remaining decimal (0.768) by 60 to get seconds: 0.768 × 60 = 46.08. The result is 40°42'46.08". For negative values (west longitude or south latitude), drop the minus sign and add the correct direction letter (W or S).

Q: Why does a negative longitude mean west?

The Prime Meridian (0° longitude) passes through Greenwich, England. Longitudes east of Greenwich are positive, and longitudes west of Greenwich are negative in the decimal degrees system. So -74.0060 means 74.0060 degrees west of Greenwich — which is New York City. Similarly, negative latitude values represent positions south of the equator. This signed convention is universally used in digital mapping systems.

Q: Which GPS coordinate format does Google Maps use?

Google Maps primarily uses Decimal Degrees (DD) in its URLs and API. When you right-click a location on Google Maps and select 'What's here?', the coordinates shown in the info card are in DD format. However, you can search in DMS format too — Google Maps accepts inputs like '40°42'46"N 74°0'21"W' and converts them automatically. For sharing or embedding coordinates programmatically, DD is always the simplest and most reliable format.

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What are GPS coordinate formats?

Every location on Earth can be described by two numbers: its latitude (north-south position relative to the equator) and its longitude (east-west position relative to the Prime Meridian through Greenwich, England). Both are measured in degrees — a full circle is 360°. The difference between the three main formats is simply how the fractional part of a degree is expressed: as a decimal, as minutes and seconds, or as decimal minutes.

The three formats are mathematically equivalent — they describe the exact same physical point. Converting between them is straightforward arithmetic, but doing it manually for a list of coordinates is tedious and error-prone. A coordinate converter handles the math instantly and eliminates transcription mistakes.

The three GPS coordinate formats explained

Here is how the same location — Times Square in New York City — looks in each format:

Decimal Degrees (DD): 40.7580, -73.9855 — The latitude and longitude are expressed as plain decimal numbers. Positive latitude is north, negative is south. Positive longitude is east, negative is west. This is the dominant format in software, web APIs, databases, and URLs.
Degrees, Minutes, Seconds (DMS): 40°45'28.8"N 73°59'7.8"W — Each degree is divided into 60 arcminutes, and each arcminute into 60 arcseconds. This format appears on topographic maps, aviation charts, and in many GPS receivers' display modes. It can feel more intuitive for navigation since it mirrors how we think about time.
Degrees Decimal Minutes (DDM): 40°45.480'N 73°59.130'W — A hybrid: whole degrees plus decimal minutes (no seconds). This is the default output of most handheld GPS devices and the format used on nautical charts. It splits the difference between the precision of DD and the readability of DMS.

How to convert GPS coordinates — step by step

Converting from Decimal Degrees to DMS by hand uses only multiplication and division. Here is the full process with a real example:

Step 1: Identify the input format and value. Suppose you have a latitude of 40.7128°N in Decimal Degrees. Note the direction (N, S, E, or W) separately, or infer it from the sign (positive = N or E, negative = S or W).
Step 2: Extract the whole degrees. The integer part of 40.7128 is 40°. Keep the decimal remainder: 0.7128.
Step 3: Convert the decimal to minutes. Multiply 0.7128 × 60 = 42.768. The whole number (42) is the arcminutes. Keep the decimal remainder: 0.768. If you only need DDM format, you are done: 40°42.768'N.
Step 4: Convert the decimal minutes to seconds. Multiply 0.768 × 60 = 46.08. This is the arcseconds value. The full DMS result is 40°42'46.08"N. For the reverse (DMS to DD), divide seconds by 3600, divide minutes by 60, and add to whole degrees.

Tips and best practices

Always specify the hemisphere. A coordinate like 40°42'46" is ambiguous without N/S/E/W or a sign. When sharing coordinates with others, include the direction letters — or use the signed DD format where negative latitude means south and negative longitude means west.
Check your decimal separator. Some countries use a comma as the decimal separator. If you copy coordinates from a non-English source and see 40,7128 instead of 40.7128, you may need to replace the comma with a period before pasting into mapping software.
Be precise — one arcsecond is about 31 meters. One degree of latitude is approximately 111 km. One arcminute is about 1.85 km. One arcsecond is roughly 31 meters. Rounding errors can place a pin in the wrong city block, so retain at least 4–6 decimal places in DD format for practical use.
Watch the coordinate order. Some systems expect latitude first (lat, long), while others use longitude first (long, lat). GeoJSON, for example, uses longitude, latitude. Google Maps expects latitude, latitude. Always confirm the expected order before pasting into a new system.

Frequently asked questions

What is the difference between DD, DMS, and DDM formats?

Decimal Degrees (DD) expresses latitude and longitude as simple decimal numbers, such as 40.7128, -74.0060. It is the most common format in software, APIs, and databases. Degrees, Minutes, Seconds (DMS) breaks each coordinate into degrees, arcminutes, and arcseconds — for example 40°42'46"N — and is common on paper maps and in aviation and maritime navigation. Degrees Decimal Minutes (DDM) is a hybrid that uses whole degrees plus decimal minutes, like 40°42.767'N, and is the default format for most GPS receivers and nautical charts.

How do I convert decimal degrees to DMS manually?

Take the decimal degrees value — say 40.7128. The whole number (40) is the degrees. Multiply the decimal part (0.7128) by 60 to get minutes: 42.768. The whole number (42) is the minutes. Multiply the remaining decimal (0.768) by 60 to get seconds: 46.08. Result: 40°42'46.08". For negative values, drop the minus sign and add the direction letter W (for longitude) or S (for latitude).

Why does a negative longitude mean west?

The Prime Meridian at 0° longitude passes through Greenwich, England. Longitudes east of Greenwich are positive, and longitudes west of Greenwich are negative in the decimal degrees system. So -74.0060 means 74.0060 degrees west of Greenwich — which corresponds to New York City. Negative latitude values represent positions south of the equator. This signed convention is universally used in digital mapping and geospatial software.

Which GPS coordinate format does Google Maps use?

Google Maps primarily uses Decimal Degrees in its URLs and API. When you right-click a location on Google Maps and select "What's here?", the coordinates shown are in DD format. However, you can also search using DMS format — Google Maps accepts inputs like 40°42'46"N 74°0'21"W and converts them automatically. For sharing or embedding coordinates programmatically, DD is always the simplest and most reliable format to use.

Conclusion

GPS coordinate formats can seem confusing at first, but once you understand that DD, DMS, and DDM are just three different ways of writing the same fractional degree value, the math becomes intuitive. For software and APIs, stick with Decimal Degrees. For paper maps and navigation instruments, DMS and DDM are more human-readable. Use the free GPS Coordinate Converter to switch between all three formats in seconds — no manual arithmetic required.

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