Convert DMS to Decimal Degrees

Degrees, Minutes, and Seconds (DMS) is a traditional coordinate format, but modern apps use Decimal Degrees. Convert between them easily with professional accuracy.

How to Use

Enter Degrees (D), Minutes (M), and Seconds (S) for both Latitude and Longitude. Click Convert.

Online Tool

Lat:
Lon:

⚠️ Datum Hazard: Read Before Conversion

Coordinate values only have meaning when attached to a Datum.

WGS84: Standard for GPS, Google Maps, Web Mercator.
NAD27: Used in older USGS topographic maps (pre-1983).

Using the wrong datum can shift your position by 20-100+ meters. Always verify the source datum of your coordinates.

🔍 What does decimal degrees mean?

Decimal degrees represent geographic position as a single number per axis. For example, 40.7128°N, -74.0060°W is the standard modern format used by GIS, GPS APIs, and mapping libraries. Each 0.0001° of latitude ≈ 11.1m, and 0.00001° ≈ 1.1m — so 5 decimal places give roughly 1-meter accuracy.

⚠️ What if the datum was wrong?

Positive/negative sign errors are the biggest risk in decimal degree data. South latitudes must be negative, West longitudes must be negative. A sign error places a point symmetrically across the equator or prime meridian — potentially thousands of kilometers from the true location.

→ Survey Datum Risk Simulator

📐 DISPLAY MODE: Standard Professional ▼

Use Cases

Entering survey data into GIS software.
Converting old map coordinates for GPS use.

FAQ

Q: What is DMS?

A: DMS stands for Degrees, Minutes, Seconds (e.g., 35° 40' 12").

Q: How precise is this?

A: It uses standard 64-bit floating point arithmetic, accurate to sub-millimeter levels.

Q: Does it handle South/West?

A: Yes. Currently inputs assume positive values, but generated decimal degrees will be positive. (Note: Future update will handle hemisphere). *Self-correction: Logic assumes absolute input. User should interpret sign.*

Professional Verification Disclaimer

This content is provided for decision-support and educational purposes for geospatial professionals and does not constitute legal, surveying, or engineering advice. Regulations and official standards vary by jurisdiction and project scope. Information is based on publicly available standards as of January 11, 2026. For critical projects, always verify current requirements with:

Licensed Professional Surveyors or Professional Engineers (PE) in the relevant jurisdiction
Certified attorneys for legal interpretation of regulations
Current guidelines from relevant authorities (FAA, JCAB, GSI, etc.)

Reference: Professional Use & Scope

Related Coordinate Conversion Tools

US State Plane (SPCS) Converters & Local Guides

Professional engineering and surveying transformations from state-specific conformal grids to GPS WGS84.

📚 Fundamental Mapping Guides

Master geodetic theory and standard operating procedures to avoid expensive liability.

⚠️ Common Transformation Errors

The 1-2 Meter (3-6 Foot) NAD83 Shift: Because the North American Plate drifts, WGS84 and NAD83(2011) are currently out of sync by up to 2 meters in the conterminous US. Mixing these datums in construction or boundary litigation is catastrophic. Understand the precise offset mechanics.

🏛️ Reality-Anchor Case Studies

🌎 US State Plane (SPCS) Tool Hubs

High-accuracy Engineering & Cadastral Conversions (Lambert Conformal Conic / Transverse Mercator).

❓ Transformation Data FAQs

What is the MGRS precision level equivalent to distance?

MGRS precision depends on the digits after the 100km identifier: 10-digit (1 meter), 8-digit (10 meters), 6-digit (100 meters), and 4-digit (1,000 meters). True positional accuracy depends entirely on your initial GPS geometry collection.

Is UTM or State Plane Coordinate System (SPCS) more accurate?

SPCS zones are designed per state and minimize scale distortion (often 1:10,000) for a smaller confined footprint. UTM covers 6-degree global bands resulting in greater stretch (around 1:2,500). SPCS is highly preferred for US construction and cadastral surveys.

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Professional Risk Notice

Using the wrong datum or applying coordinates without grid-to-ground correction can cause 1–400 metre positional errors — a leading cause of surveying negligence claims and contract disputes.

📋 See Legal Cases ($25K–$10M) → 📝 Contract Datum Risk → ⚙️ Calculate My Exposure →