Lat Lon to Decimal: Convert Coordinates Easily

This calculator converts latitude and longitude coordinates from degrees, minutes, and seconds (DMS) or degrees and decimal minutes (DM) into decimal degrees (DD). You enter the degrees, minutes, and seconds (or just degrees and minutes) for either latitude or longitude, and the tool returns the decimal value you need for GPS, mapping, and data analysis.

Formula

The conversion from DMS to decimal degrees is straightforward:

Decimal Degrees = Degrees + (Minutes / 60) + (Seconds / 3600)

• Degrees (°): the whole number part of the coordinate (e.g., 45°).
• Minutes (‘): the fractional part expressed in minutes (1° = 60′).
• Seconds (“): the further fractional part in seconds (1′ = 60″).
• Direction: positive for North/East, negative for South/West.

For DM (degrees and decimal minutes), just omit the seconds: Decimal = Degrees + (Minutes / 60).

Worked Example

Using the default values from the calculator: 45° 30′ 15″ N.

1. Degrees = 45
2. Minutes = 30 → 30 / 60 = 0.5
3. Seconds = 15 → 15 / 3600 = 0.0041667
4. Sum = 45 + 0.5 + 0.0041667 = 45.5041667°
5. Direction N = +1, so the result is 45.504167° (rounded to 6 decimal places).

If the direction were S, the result would be -45.504167°.

Why Use Decimal Degrees?

Decimal degrees are the standard for digital mapping and GPS because they store coordinates as a single number, making calculations and comparisons easier. Most online maps, GIS software, and data formats (like GeoJSON) expect DD. Converting from DMS avoids errors when entering coordinates manually and simplifies distance calculations.

How to Choose the Right Format

You’ll encounter three common formats:

• DMS (Degrees, Minutes, Seconds): e.g., 45° 30′ 15″ N – used on paper maps and some nautical charts.
• DM (Degrees, Decimal Minutes): e.g., 45° 30.25′ N – used by many GPS devices and aviation.
• DD (Decimal Degrees): e.g., 45.504167° – used by most software and web APIs.

If you have DM, simply divide the decimal minutes by 60 and add to the degrees. If you have DMS, divide seconds by 3600 as well.

Common Mistakes and Pitfalls

• Forgetting the sign: A coordinate without a direction (N/S/E/W) is ambiguous. Always include the sign or the hemisphere.
• Mixing up minutes and seconds: 1 minute = 60 seconds, not 100. A common error is dividing seconds by 100 instead of 3600.
• Rounding too early: Rounding minutes or seconds before converting can shift the location by hundreds of meters. Keep full precision until the final answer.
• Using the wrong direction: Latitudes are N/S, longitudes are E/W. Swapping them puts you on the opposite side of the world.

Accuracy and Precision

Decimal degrees with 5 decimal places give about 1 meter accuracy, 6 decimal places about 0.1 meter. For most mapping purposes, 6 decimal places is sufficient. If you need centimeter-level accuracy (e.g., surveying), use 7 or more decimals, but be aware that GPS itself has limited accuracy (typically 3-5 meters).

Alternatives to Manual Conversion

Besides this calculator, you can convert coordinates using:

• Online mapping tools that accept DMS input directly.
• Spreadsheet formulas: for example, in Excel, =deg + min/60 + sec/3600.
• Programming languages: Python, JavaScript, etc., have built-in math functions.

But a dedicated calculator like this one gives you an instant, error-free result without needing to remember formulas.

Frequently Asked Questions

What is the difference between latitude and longitude?

Latitude measures north-south position relative to the equator (0° to 90° N/S). Longitude measures east-west position relative to the Prime Meridian (0° to 180° E/W). Both are needed to pinpoint a location.

How do I know if a coordinate is latitude or longitude?

Latitude values are between -90 and 90, while longitude values are between -180 and 180. Also, latitude is often written first, but not always—check the context.

Can I convert from decimal degrees back to DMS?

Yes. Take the decimal part, multiply by 60 to get minutes, then take the remaining decimal and multiply by 60 to get seconds. For example, 45.504167° → 45° + 0.504167*60 = 30.25′ → 0.25*60 = 15″.

Why do some coordinates have negative numbers?

Negative decimal degrees indicate South (for latitude) or West (for longitude). For example, -33.8688 is Sydney, Australia (south of the equator).

What is the maximum number of decimal places needed?

For most practical purposes, 6 decimal places (about 0.1 meter) is overkill but safe. 4 decimal places gives about 11 meters, which is fine for city-level accuracy.

Does this calculator work for both latitude and longitude?

Yes. The math is identical; just choose the appropriate direction (N/S for latitude, E/W for longitude). The calculator doesn’t distinguish between them.

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in deg | Degrees | ° | 45 | 0
in min | Minutes | ' | 30 | 0
in sec | Seconds | " | 15 | 0
in dir | Direction | N=1, S=-1, E=1, W=-1 | 1 | 0
out dd | Decimal degrees | ° | dir * (deg + min/60 + sec/3600) | 6