What is the difference between decimal degrees and DMS?

Decimal degrees (DD) express latitude and longitude as a single floating-point number, e.g. 37.7749° N. DMS splits the same angle into whole degrees, whole minutes, and decimal seconds, e.g. 37° 46' 29.64" N. Both represent the same position; chart plotters and GPS units typically use DD while paper charts and verbal reports often use DMS.

What is DDM (degrees-decimal-minutes) format?

DDM (also written DD MM.MMM) is a third format used by many GPS units and NMEA sentences. It keeps whole degrees but expresses the remainder as decimal minutes rather than splitting into minutes and seconds. For example, 37° 46.494' N. This tool also outputs DDM alongside DD and DMS.

What is NMEA-style output?

NMEA 0183 is the serial data standard used by marine electronics. Latitude appears as DDMM.MMMM (4 integer digits for degrees+minutes, then decimals) followed by N or S; longitude as DDDMM.MMMM followed by E or W. Many chart plotters and VHF radios accept waypoints in this format.

How precise are the conversions?

The tool retains 6 decimal places in decimal degrees (about 0.1 m precision at the equator) and rounds seconds to 3 decimal places in DMS, which is better than 1 cm. For practical navigation, 4–5 decimal degree places (roughly 1–11 m) is more than sufficient.

Can I enter negative decimal degrees?

Yes. Negative latitude means South (e.g. −33.8688 = 33.8688° S). Negative longitude means West (e.g. −70.6693 = 70.6693° W). The tool automatically sets the hemisphere indicator when you enter a negative DD value.

Latitude/Longitude Marine Coordinate Converter

Convert latitude and longitude between decimal degrees and DMS (degrees-minutes-seconds) formats, with hemisphere selectors and NMEA-style output for marine navigation.

Decimal Degrees (DD)

Latitude (−90 to 90, negative = South)

Longitude (−180 to 180, negative = West)

Degrees-Minutes-Seconds (DMS)

Latitude

° ' "

N S

Longitude

° ' "

E W

Enter coordinates on the left to see all formats.

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Summary

Convert latitude and longitude between decimal degrees and DMS (degrees-minutes-seconds) formats, with hemisphere selectors and NMEA-style output for marine navigation.

How it works

Enter a latitude in decimal degrees (e.g. 37.7749) or in DMS form (e.g. 37° 46' 29.64" N).
Enter a longitude in decimal degrees (e.g. -122.4194) or in DMS form (e.g. 122° 25' 9.84" W).
Select the hemisphere (N/S, E/W) using the radio buttons if entering DMS.
Click Convert or press Enter to calculate all formats.
Copy the NMEA-style string for use in chart software or GPS devices.
To convert in reverse, enter DMS values in the DMS panel and click Convert DMS → DD / DDM.

Use cases

Transcribe a paper chart fix into decimal degrees for entry into navigation software.
Convert a GPS waypoint from decimal degrees to DMS for verbal radio position report.
Format coordinates in NMEA style for AIS, VHF DSC, or EPIRB programming.
Double-check hand-plotted DMS positions against a digital chart plotter.
Prepare waypoint lists for offshore passage planning.
Teach student navigators the relationship between DD and DMS formats.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu

Latitude/Longitude Marine Coordinate Converter

Decimal Degrees (DD)

Degrees-Minutes-Seconds (DMS)

Decimal Degrees (DD)

Degrees-Minutes-Seconds (DMS)

Degrees-Decimal Minutes (DDM)

NMEA 0183 Style

Summary

How it works

Use cases

Frequently Asked Questions

Latitude/Longitude Marine Coordinate Converter

Use the Latitude/Longitude Marine Coordinate Converter

Decimal Degrees (DD)

Degrees-Minutes-Seconds (DMS)

Decimal Degrees (DD)

Degrees-Minutes-Seconds (DMS)

Degrees-Decimal Minutes (DDM)

NMEA 0183 Style

Summary

How it works

Use cases

Frequently Asked Questions