Latitude/Longitude Marine Coordinate Converter

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

1. Enter a latitude in decimal degrees (e.g. 37.7749) or in DMS form (e.g. 37° 46' 29.64" N).
2. Enter a longitude in decimal degrees (e.g. -122.4194) or in DMS form (e.g. 122° 25' 9.84" W).
3. Select the hemisphere (N/S, E/W) using the radio buttons if entering DMS.
4. Click Convert or type in any field — both formats update instantly.
5. Copy the NMEA-style string for use in chart software or GPS devices.
6. Use the Swap button to reverse direction (DD→DMS or DMS→DD).

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