DMS to Decimal Degrees Converter - Free Online

Convert Degrees, Minutes, and Seconds (DMS) to decimal latitude and longitude online for free with this DMS to decimal degrees converter. It transforms coordinates like 40° 26' 46" N into the modern decimal format (40.446111°) used by GPS devices, geocoding APIs, and mapping software. Perfect for GPS navigation, geocaching, and GIS — just enter your DMS values and get precise decimal coordinates in seconds.

Decimal degrees are the format most software expects: a single signed number that is easy to store, compare, and pass to mapping libraries. This converter collapses DMS notation into that number while preserving the hemisphere. To go the other way, use the Lat Long to DMS tool.

Why Convert DMS to Decimal Degrees?

A DMS to decimal converter is the bridge between legacy coordinate notation and modern software. Aviation charts, marine plots, survey plats, and legal property descriptions still use degrees–minutes–seconds, but every mapping API, GPS app, geocoding service, and spatial database expects a single signed decimal number. Converting by hand invites sign errors on south and west hemispheres that silently place points on the wrong side of the planet.

This degrees minutes seconds to decimal tool handles the arithmetic and the hemisphere correctly every time, whether the input uses symbols (° ' "), letter suffixes (N/S/E/W), or signed values. Because conversion runs entirely in your browser, you can safely process coordinates from confidential surveys, client sites, or sensitive locations without uploading them anywhere.

Live Example

DMS collapses into a single decimal value per axis, with the sign carrying the hemisphere:

48° 51' 30.24" N
2° 17' 40.20" E

Latitude:  48.8584
Longitude: 2.2945

How to Convert Degrees Minutes Seconds to Decimal Degrees

1. Enter Latitude Values: Type the degrees, minutes, and seconds for your latitude.
2. Enter Longitude Values: Type the degrees, minutes, and seconds for your longitude.
3. Convert: Click Convert to calculate high-precision decimal coordinates.
4. Copy or Download: Copy the decimal coordinates to your clipboard or save them as a text file.

Key Features

• ✅ Convert latitude and longitude from DMS to decimal degrees
• ✅ Support for positive and negative coordinates
• ✅ High-precision output with six decimal places
• ✅ Copy converted coordinates to clipboard
• ✅ Download coordinates as a text file
• ✅ Input validation for accurate results

Common Use Cases

• GPS Devices: Convert traditional DMS coordinates for use in modern GPS receivers.
• Mapping Software: Prepare coordinates for Google Maps, QGIS, and other web mapping tools.
• Geocaching: Transform DMS waypoints into decimal format for geocaching apps.
• GIS Applications: Standardize survey and location data for geographic information systems.

Benefits of Using Our Tool

• ✅ Free to use with no registration required
• ✅ Instant, high-precision conversions
• ✅ Handles positive and negative coordinates
• ✅ Copy and download results in one click
• ✅ All processing in your browser—your data stays private

About Converting DMS to Decimal Degrees

DMS (degrees, minutes, seconds) divides each degree into 60 minutes and each minute into 60 seconds — the same way an hour is divided. To collapse it into a single decimal degree value, convert the minutes and seconds into a fraction of a degree and add them to the whole degrees: decimal = degrees + (minutes / 60) + (seconds / 3600). The hemisphere letter sets the sign: N and E are positive, S and W are negative.

Decimal degrees are what computers prefer. GPS devices, Google Maps URLs, geocoding APIs, and spatial databases all use signed decimal values because they sort, compare, and compute distances with simple arithmetic (no need to carry three fields per axis). Latitude stays within ±90 and longitude within ±180, which makes range validation trivial. For most street-level work, five decimal places (about 1.1 m) is plenty; fewer is fine for city-level mapping.

The tricky part of DMS parsing is the variety of input styles — 48°51'30"N, 48 51 30 N, or 48.8584 — and handling the rollover when seconds or minutes reach 60. A robust converter normalises all of these and applies the hemisphere sign correctly. To reverse the conversion, use the Lat Long to DMS tool.

Common Errors and How to Fix Them

• Wrong sign on the result: The hemisphere sets the sign. South (S) latitudes and West (W) longitudes must always yield negative decimal values; omitting directional indicators defaults to positive values, plotting your coordinates in the incorrect hemisphere.
• Value out of range: Latitude degrees must be between -90 and +90, while longitude degrees must fall between -180 and +180. Any minute or second value greater than or equal to 60 indicates an uncarried overflow that must be rolled into higher units.
• Input notation mismatch: Ensure minutes and seconds are numeric values. If your source coordinates contain fractional minutes (e.g., 40° 26.767' N), you are working with DDM (Degrees Decimal Minutes) rather than DMS, requiring separate arithmetic.
• Latitude and longitude swapped: Latitude (North/South) never exceeds ±90°, whereas longitude (East/West) extends to ±180°. Submitting a longitude coordinate greater than 90° into the latitude input field will trigger a validation error.

Coordinate Systems: DMS vs. DDM vs. Decimal Degrees

Different industries and hardware devices record spatial positioning using distinct notation formats. Understanding these conventions ensures seamless data exchange across surveying, maritime navigation, and web mapping platforms:

Mathematical Conversion Formula: DMS to Decimal Degrees

Converting degrees, minutes, and seconds into decimal degrees is achieved by converting minutes and seconds into fractional base-60 degree components and summing them:

To preserve hemisphere direction, apply a negative sign if the coordinate lies in the Southern hemisphere (South / S) or Western hemisphere (West / W):

1. Divide Minutes by 60: One degree contains 60 arcminutes. A value of 30 minutes equals 30 / 60 = 0.5°.
2. Divide Seconds by 3600: One degree contains 3,600 arcseconds (60 minutes × 60 seconds). A value of 45 seconds equals 45 / 3600 = 0.0125°.
3. Sum the Values: Add the absolute degrees, fractional minutes, and fractional seconds: 40 + 0.433333 + 0.012778 = 40.446111°.
4. Apply Directional Sign: If the hemisphere is South or West (or negative degree value), multiply the final sum by -1. For example, 73° 59' 11" W becomes -(73 + 59/60 + 11/3600) = -73.986389°.

How to Convert DMS to Decimal Degrees in Code

When parsing geographical datasets or coordinate telemetry feeds, implement the conversion algorithm programmatically using these clean JavaScript and Python reference functions:

function dmsToDecimal(degrees, minutes, seconds, hemisphere) {
  const deg = Math.abs(Number(degrees) || 0);
  const min = (Number(minutes) || 0) / 60;
  const sec = (Number(seconds) || 0) / 3600;
  let dd = deg + min + sec;

  const hemi = String(hemisphere).trim().toUpperCase();
  if (hemi === 'S' || hemi === 'W' || degrees < 0) {
    dd = -dd;
  }

  return Number(dd.toFixed(6));
}

// Example: 40 deg 26 min 46 sec N
console.log(dmsToDecimal(40, 26, 46, 'N')); // 40.446111

def dms_to_decimal(degrees: float, minutes: float, seconds: float, hemisphere: str = 'N') -> float:
    deg = abs(float(degrees))
    min_fraction = float(minutes) / 60.0
    sec_fraction = float(seconds) / 3600.0
    dd = deg + min_fraction + sec_fraction

    hemi = str(hemisphere).strip().upper()
    if hemi in ('S', 'W') or degrees < 0:
        dd = -dd

    return round(dd, 6)

# Example: 73 deg 59 min 11 sec W
print(dms_to_decimal(73, 59, 11, 'W')) # -73.986389