What do the N, S, E, W letters mean?

N (North) and S (South) indicate whether a latitude is in the Northern or Southern Hemisphere, and E (East) and W (West) indicate whether a longitude is east or west of the prime meridian. In decimal form, northern latitudes are positive and southern latitudes are negative, while eastern longitudes are positive and western longitudes are negative. Hemisphere letters remove that sign convention from the number itself.

Latitude Longitude Converter (DMS ↔ Decimal) - Free

Q: What is the difference between decimal degrees and DMS?

Decimal degrees express latitude and longitude as a single floating-point number per axis, for example 40.7128 for New York's latitude. Degrees-minutes-seconds (DMS) breaks the same angle into three components: whole degrees, arc minutes (sixtieths of a degree), and arc seconds (sixtieths of a minute), plus a hemisphere letter. Decimal degrees are easier to store and compute with, while DMS is the traditional format on navigation charts and older maps.

Q: Which format should I use?

Use decimal degrees for software, GPS devices, APIs, and spreadsheets, because every modern system accepts them as a single number and they are easier to sort and compare. Use DMS when reading nautical charts, USGS topographic maps, aviation sectionals, or older surveying documents, which still display coordinates in the traditional three-part format. Many apps let you switch between the two in their settings.

Q: How precise is one arc second?

One arc second of latitude is about 30.87 meters on the ground, and one arc second of longitude is about 30.87 × cos(latitude) meters, which shrinks as you move toward the poles. Six decimal places of decimal degrees give you roughly 0.11 meter resolution, which is enough for most surveying and all consumer mapping uses.

Convert between decimal degrees and degrees-minutes-seconds (DMS) coordinate formats in both directions. Paste GPS coordinates or chart readings and get the other format instantly.

How to Use the Latitude/Longitude Converter

Choose a direction at the top of the converter: DMS to Decimal if you have coordinates like 40°42'46"N that you want to paste into software, or Decimal to DMS if you have a number like 40.7128 that you want to show on a nautical chart or in a traditional map annotation. Enter the values and the calculator instantly displays the other format. Hemisphere letters (N/S for latitude, E/W for longitude) are handled automatically: a southern or western value in decimal form becomes negative, and the DMS form uses S or W without a minus sign.

Decimal Degrees vs DMS — Which Should You Use?

Decimal degrees are preferred by virtually all modern software, including GPS devices, smartphones, GIS systems, APIs, and spreadsheets. They are a single number per axis, easy to sort, easy to compute with, and they avoid the awkward sexagesimal arithmetic that DMS demands. Degrees-minutes-seconds remains the traditional format on printed nautical charts, aviation sectionals, USGS topographic maps, and older surveying documents. Many field users still prefer DMS because it is more human-readable: 40°42'46"N is immediately recognizable as "about two-thirds of the way between the 40th and 41st parallel, almost exactly on a specific minute," whereas 40.7128 takes a mental step to interpret.

Understanding Precision

One degree of latitude is approximately 111 kilometers on the ground, one arc minute is about 1.85 kilometers, and one arc second is roughly 31 meters. For longitude, the same values hold at the equator and shrink with the cosine of the latitude as you move toward the poles. If you need to pinpoint a location to the nearest meter, you need coordinates precise to about 5 decimal places in decimal degrees, or to hundredths of a second in DMS. Six decimal places is overkill for anything non-survey-grade; use fewer digits on casual maps to avoid implying false precision.

Common Pitfalls

The most common mistake when entering coordinates is forgetting the sign for the western and southern hemispheres. Decimal latitudes in the Southern Hemisphere must be negative, and decimal longitudes in the Western Hemisphere must be negative. Another common error is mixing up latitude and longitude: latitude always comes first in most formats, but some mapping systems, notably GeoJSON, reverse the order to longitude-latitude. When in doubt, remember that latitude is limited to the range -90 to 90, while longitude can span -180 to 180, so a value above 90 in the "latitude" field is a clear sign you have the two swapped.

Frequently Asked Questions

What is the difference between decimal degrees and DMS?

Decimal degrees use a single floating-point number per axis. DMS splits that angle into degrees, arc minutes, and arc seconds, plus a hemisphere letter. Decimal is easier for software; DMS is traditional on charts.

How do I convert DMS to decimal degrees manually?

Take the degrees, add the minutes divided by 60, add the seconds divided by 3600, and apply a negative sign for S or W hemispheres.

Which format should I use?

Use decimal degrees for GPS, software, APIs, and spreadsheets. Use DMS when reading nautical charts, aviation sectionals, and printed maps.

What do N, S, E, W mean?

They indicate the hemisphere. N and E are positive in decimal form, while S and W are negative. In DMS you keep the value positive and add the letter instead.

How precise is one arc second?

About 31 meters of latitude, and 31 × cos(latitude) meters of longitude. Six decimal places of decimal degrees give you roughly 0.11 meter resolution.

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