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Geo & Coordinate Tools

Decimal Degrees to DMS Converter

Convert a latitude/longitude pair from decimal degrees to carry-safe DMS, edit DMS back to decimal, compare DDM, verify round-trip precision, batch mixed coordinate pairs, and copy GIS-friendly formats.

Wave188 · coordinate format workflow

Decimal Degrees ↔ DMS — pair-safe and carry-safe

Work with latitude and longitude as a pair, not as anonymous angles. Edit DD or DMS, control seconds precision, verify the displayed DMS by round trip, and copy GIS-friendly formats without losing hemisphere meaning.

Browser-local arithmetic

Latitude · decimal degreesLongitude · decimal degreesSeconds precision

Latitude DMS

Longitude DMS

Copy order: latitude, longitude

——

—Decimal degrees (DD)

—Degrees decimal minutes (DDM)

—geo: URI

—Displayed-DMS round-trip error

Enter coordinates above.

Position sanity-check grid

This graticule verifies hemisphere and rough global position. It is not a street map.

Open in Google Maps Open in OpenStreetMap

Opening an external map sends the coordinates to that provider. Conversion on this page itself stays local.

Copy-ready coordinate formats

—Selected pair order

—WKT uses longitude first

—GeoJSON coordinate array uses longitude first

Session history

Batch convert up to 100 coordinate pairs

One pair per line. Accepts decimal pairs such as 40.7128, -74.0060 or DMS pairs such as 40°42′46″N, 74°00′22″W.

Precision and coordinate order

Latitude is limited to ±90°. Longitude is limited to ±180°. If both numbers are within ±90°, swapping latitude and longitude can still produce a valid-looking but wrong location. WKT and GeoJSON coordinates conventionally use longitude first; ordinary map/GPS text often uses latitude first.

DMS seconds are rounded only for display. When rounding reaches 60, the Studio carries into minutes/degrees so it never emits 60″ or 60′.

Truth boundary: DD↔DMS is a representation conversion and does not change datum. The arithmetic works for any angular coordinate, but the map links and geographic range checks assume latitude/longitude on Earth. This page does not reverse-geocode, request device location, or silently upload coordinates.

Convert coordinates without losing sign, order or precision

Hemisphere carries the sign

For geographic coordinates, negative latitude becomes south and negative longitude becomes west. DMS minutes and seconds stay non-negative.

Rounding must carry

A displayed value such as 59.9996 seconds can round to 60.000. A correct formatter carries that into the next minute instead of printing invalid 60-second or 60-minute components.

Latitude and longitude are not interchangeable

Latitude is constrained to ±90° and longitude to ±180°, but many real pairs have both values inside ±90°. That means a swapped pair can still pass range validation and land in the wrong place.

DDM is a useful middle format

Degrees decimal minutes keeps whole degrees and expresses the rest as decimal minutes. Marine and aviation workflows often use it alongside DD and DMS.

GIS copy formats use different order

Human-readable coordinate pairs are commonly latitude, longitude. WKT POINT and GeoJSON coordinate arrays use x/y order—longitude first, then latitude.

Round-trip error shows display loss

The Studio converts the rounded DMS shown on screen back to decimal degrees and estimates the distance from the original pair. More second precision reduces this formatting error but cannot improve the source measurement itself.

Keep coordinate conventions explicit

Latitude/longitude order, hemisphere, datum and precision can all change the interpreted location. WebToolArc keeps WGS84 assumptions visible and separates conversion math from geocoding.

Verify before reuse

A formatted coordinate can look plausible while being swapped, rounded too aggressively or interpreted in the wrong system. Decode or open a map link before importing important points elsewhere.

Sign, hemisphere, and rounding

Degrees-minutes-seconds expresses the same angle as decimal degrees: the integer part is degrees, the fractional remainder is multiplied by 60 for minutes, and the remaining fraction is multiplied by 60 again for seconds. For coordinates, negative latitude normally maps to south and negative longitude to west rather than to negative minutes or seconds.

Check boundary values carefully

Rounding seconds can carry into the next minute, and rounding 59 minutes 59.999… seconds can carry into the next degree. Latitude and longitude also have different valid geographic ranges. If the output is going into GIS software, verify the expected sign/hemisphere convention and precision rather than assuming every application parses DMS text the same way.

Practical guide and verification

Keep latitude and longitude sign conventions explicit

Positive latitude is north and negative latitude is south; positive longitude is east and negative longitude is west in the usual geographic convention. When converting to DMS, the hemisphere letter carries the sign, so do not add a negative sign again to the degree component.

Carry seconds when rounding reaches sixty

Rounding 59.999 seconds to 60.00 seconds requires carrying one minute, and 59 minutes 60 seconds requires carrying one degree. A converter should normalize this boundary instead of emitting an invalid-looking DMS coordinate.

Use a round trip to verify precision

Convert decimal degrees to DMS and then convert that displayed DMS value back to decimal degrees. The difference should be consistent with the chosen seconds precision; a large mismatch usually indicates a hemisphere or degree-minute-second entry error.

Coordinate precision implies a physical scale

Extra decimal places are not free accuracy. Source GPS, map selection and datum quality limit the meaningful precision even if the formatter prints many digits. Preserve only the precision supported by the original coordinate source and the task.

Do not swap latitude and longitude

Many systems accept both numbers even when their order is reversed, producing a valid coordinate in the wrong place. Check that latitude stays within ±90 degrees and longitude within ±180 degrees, then verify the point on a trusted map when location matters.