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Coordinate Converter - DD, DMS, DDM Format

Free coordinate converter: DD, DMS, DDM formats. Bulk paste multi-line, use my location, export CSV. GPS coordinate format converter for surveyors and developers.

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Paste one coordinate per line in DD format (lat, lon). Export to CSV, KML (Google Earth), GPX (GPS devices) or GeoJSON.

What is Coordinate Conversion?

Coordinate conversion is the process of transforming geographic coordinates from one format to another. The three most common formats used for latitude and longitude are Decimal Degrees (DD), Degrees Minutes Seconds (DMS), and Degrees Decimal Minutes (DDM).

Different applications and devices use different coordinate formats. GPS devices might display coordinates in DMS format, while web mapping services like Google Maps use DD format. Converting between these formats is essential for navigation, surveying, geocaching, and geographic information systems (GIS).

Understanding coordinate formats:

  • Decimal Degrees (DD): Coordinates expressed as decimal numbers (e.g., 21.0278° N, 105.8342° E). Most common in digital mapping and web applications.
  • Degrees Minutes Seconds (DMS): Traditional format using degrees, minutes, and seconds (e.g., 21° 1' 40" N, 105° 50' 3" E). Common in navigation and surveying.
  • Degrees Decimal Minutes (DDM): Hybrid format with degrees and decimal minutes (e.g., 21° 1.668' N, 105° 50.052' E). Used by some GPS devices.

Each format has advantages: DD is simplest for calculations, DMS is traditional and precise, and DDM balances precision with readability.

How to Convert Between Coordinate Formats

Converting between coordinate formats involves understanding the relationship between degrees, minutes, and seconds:

Conversion formulas:

  • 1 degree = 60 minutes = 3600 seconds
  • DMS to DD: DD = Degrees + (Minutes/60) + (Seconds/3600)
  • DD to DMS: Extract degrees, multiply decimal by 60 for minutes, multiply remaining decimal by 60 for seconds
  • DDM to DD: DD = Degrees + (Decimal Minutes/60)
  • DD to DDM: Extract degrees, multiply decimal by 60 for decimal minutes

Example conversion from DMS to DD:

21° 1' 40.08" N = 21 + (1/60) + (40.08/3600) = 21.0278° N

Remember to use negative values for South latitude and West longitude in DD format, or add directional indicators (N/S, E/W) in DMS and DDM formats.

Common Coordinate Format Use Cases

Different coordinate formats are preferred in various applications:

  • Decimal Degrees (DD): Web mapping (Google Maps, OpenStreetMap), programming, databases, GIS software
  • Degrees Minutes Seconds (DMS): Traditional navigation, nautical charts, aviation, surveying, topographic maps
  • Degrees Decimal Minutes (DDM): Handheld GPS devices, marine GPS, recreational navigation
  • Scientific Research: DD format for data analysis and calculations
  • Mobile Apps: Usually DD for API integration, but may display DMS for user readability

Coordinate Precision and Accuracy

The precision of coordinates depends on the number of decimal places used:

  • DD with 4 decimal places ≈ 11 meters precision
  • DD with 5 decimal places ≈ 1.1 meters precision
  • DD with 6 decimal places ≈ 0.11 meters precision
  • DMS with seconds to 2 decimal places ≈ 0.3 meters precision

For most applications, 5-6 decimal places in DD format or seconds to 2 decimal places in DMS format provide sufficient accuracy for navigation and mapping purposes.

About Coordinate Converter - DD, DMS, DDM Format

Coordinate Converter translates GPS latitude/longitude between Decimal Degrees (DD), Degrees-Minutes-Seconds (DMS) and Degrees-Decimal-Minutes (DDM) — the three formats you'll encounter on Google Maps, aviation charts, marine GPS units, surveyors' notes, and old topographic atlases. Paste a single coordinate or batch-convert hundreds of lines at once, export the results as CSV, KML for Google Earth, GPX for handheld GPS, or GeoJSON for web maps. Built for pilots cross-referencing nautical and aviation charts, surveyors translating field readings, geocachers sharing waypoints, GIS developers cleaning datasets, and anyone tired of doing 1°/60-minutes/3600-seconds arithmetic by hand. Try also our Distance Bearing and Address Geocoder.

Frequently Asked Questions

All three describe the same point on Earth using latitude and longitude, but they package degrees differently. Decimal Degrees (DD) writes the full angle as one decimal number, like 21.0278, which is the easiest form for spreadsheets, databases, and web APIs like Google Maps or OpenStreetMap. Degrees Minutes Seconds (DMS) splits the angle into integer degrees, integer minutes (1/60 of a degree), and seconds with optional decimals (1/3600 of a degree), written 21° 1' 40.08" N — the traditional form on nautical charts, aviation maps, and surveying documents. Degrees Decimal Minutes (DDM) is a hybrid used by many handheld GPS units and the marine community: integer degrees plus decimal minutes, like 21° 1.668' N. ISO 6709 accepts all three, so conversion is purely cosmetic — no precision is lost as long as you keep enough digits.

In DD format, the sign carries the hemisphere: positive latitudes are North, negative are South; positive longitudes are East, negative are West. So 21.0278 is 21.0278° N, and -21.0278 becomes 21.0278° S. When converting to DMS or DDM, take the absolute value before splitting into degrees/minutes/seconds, then append the cardinal letter at the end: -21.0278 → 21° 1' 40.08" S. Going the other way, strip the cardinal letter, compute the decimal magnitude, then prefix a minus sign if the letter was S or W. A common mistake is keeping the minus sign in the degrees field of DMS (-21° 1' 40"), which most parsers reject. This converter handles both conventions, but for cross-system data exchange always pick one and document it.

Three things typically diverge. First, format: your GPS may show DMS or DDM while Google shows DD, and a hasty conversion can drop a decimal place. Second, datum: nearly all modern devices use WGS84, but older topographic maps or some national GPS units (especially in Europe and Asia) use NAD27, ED50, or Tokyo Datum, which can shift the same point by 100-200 meters. Third, precision: a handheld GPS reading is accurate to roughly 3-5 meters under open sky, while Google's pin reflects a published address centroid that may be on the building roof or street segment, not the actual entrance. Always compare apples to apples — convert both to DD WGS84 and treat differences under about 10 meters as instrument noise rather than a real mismatch.

WGS84 (World Geodetic System 1984) is the global reference ellipsoid maintained by the U.S. National Geospatial-Intelligence Agency and used by GPS satellites, web maps, and most modern GIS software. It models Earth as an oblate ellipsoid with semi-major axis 6,378,137 m and flattening 1/298.257223563. "Datum" matters because the same latitude-longitude pair refers to a slightly different physical point on different ellipsoids. Converting between WGS84 and a regional datum like NAD83 (North America) or GDA94 (Australia) involves a Helmert 7-parameter transformation, not just a coordinate format change. Within centimeters NAD83(2011) and WGS84(G2139) agree in CONUS, but legacy NAD27 can be off by 30-100 m. This converter assumes WGS84 throughout — convert your data into WGS84 before using it.

Precision in DD scales by about 11 meters per 1/10000th of a degree at the equator (shrinking by cos(latitude) east-west). Useful benchmarks: 1 decimal place ≈ 11 km (country / region), 2 places ≈ 1.1 km (city), 3 places ≈ 110 m (neighborhood), 4 places ≈ 11 m (individual building), 5 places ≈ 1.1 m (tree, lamppost), 6 places ≈ 11 cm (survey marker), 7 places ≈ 1.1 cm (cadastral corner). In DMS, 1 second of latitude ≈ 30.9 m, so two decimal places in the seconds field give roughly 0.3 m. Storing more digits than your source supports is misleading — a GPS fix accurate to 5 m doesn't gain accuracy by being written out to 8 decimal places. Round to match real-world uncertainty.

Latitude lines are parallel circles, so 1° of latitude is always about 111.13 km (slightly more near the poles because of Earth's oblate shape). Longitude lines are meridians that all meet at the poles, so 1° of longitude shrinks with latitude: at the equator it's 111.32 km, at 30° it's about 96.49 km, at 45° about 78.85 km, at 60° about 55.80 km, and at the poles it's zero. The formula is 1° longitude ≈ 111.32 × cos(latitude) km. This matters when designing bounding boxes, grid cells, or proximity queries: a query of "within 0.01° in any direction" defines a square at the equator but a tall thin rectangle near Helsinki. For distance-based queries, always project to meters or use the haversine formula instead of degree boxes.

ISO 6709 is the international standard for representing geographic point locations in a machine-readable text string. Its short form puts latitude, longitude, and optional altitude as signed numbers with mandatory sign characters and explicit field widths: +21.0278-105.8342+010.0/ — the slash terminates the string and altitude is in meters. The standard also accepts DMS variants and CRS (coordinate reference system) tags. It's widely used in XMP photo metadata, Google's KML extensions, and some MPEG/EXIF profiles. For human-facing UIs, plain "21.0278, 105.8342" is friendlier; for inter-system data exchange or batch geocoding pipelines, ISO 6709 removes ambiguity about which value is which and which hemisphere applies. This converter can output a Google Maps URL, which is the de facto modern equivalent for sharing single points.

Yes, but check the datum and the meridian. Pre-1980 maps in the United States often use NAD27 with the Clarke 1866 ellipsoid; converting them to WGS84 requires a datum shift of roughly 30-90 m depending on the state. European maps may use ED50 (shifts 100-200 m from WGS84). French maps before 2000 used the Paris meridian instead of Greenwich, so all longitudes are offset by 2.337229° — failing to account for that drops you several kilometers east. Old Russian maps used Pulkovo 1942. This tool only does format conversion (DD ↔ DMS ↔ DDM), not datum transformation: if your source is on a non-WGS84 datum, use a tool like cs2cs (from PROJ) or QGIS to do the geodetic shift first, then run the result through this converter for cosmetic reformatting.
Coordinate Converter - DD, DMS, DDM Format — Free coordinate converter: DD, DMS, DDM formats. Bulk paste multi-line, use my location, export CSV. GPS coordinate form
Coordinate Converter - DD, DMS, DDM Format
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