Convert Lat Long to Hours Minutes Seconds?

This calculator converts a pair of latitude and longitude coordinates from decimal degrees into hours, minutes, and seconds of arc. You enter the decimal degree value (for example, 37.7749) and the calculator outputs the equivalent in degrees, minutes, and seconds (37° 46′ 29.64″). The result also shows the direction (N, S, E, W) based on the sign of the input, so you can directly use it for mapping, navigation, or astronomy.

Formula

The conversion from decimal degrees (DD) to degrees, minutes, and seconds (DMS) follows a simple three-step process:

• Degrees: The whole number part of the decimal degree value (ignore the sign for now).
• Minutes: Multiply the fractional part by 60. The whole number part of the result is the minutes.
• Seconds: Multiply the fractional part of the minutes by 60. The result is the seconds, usually rounded to two decimal places.

In mathematical notation, for a decimal degree value D:

Degrees = floor(|D|)
Minutes = floor((|D| - Degrees) × 60)
Seconds = ((|D| - Degrees) × 60 - Minutes) × 60

Where |D| is the absolute value of the decimal degree. The sign of the original value determines the hemisphere: positive latitude is North, negative is South; positive longitude is East, negative is West.

Worked Example

Using the default input of 37.7749 (the latitude of San Francisco, California):

1. Absolute value: |37.7749| = 37.7749
2. Degrees = floor(37.7749) = 37
3. Fractional part = 37.7749 – 37 = 0.7749
4. Minutes = floor(0.7749 × 60) = floor(46.494) = 46
5. Seconds = (46.494 – 46) × 60 = 0.494 × 60 = 29.64

So 37.7749° = 37° 46′ 29.64″. Since the input is positive, the direction is North. The calculator’s first output shows the DMS value, and the second output shows “N/E� for positive inputs.

Why Convert Between DD and DMS?

Decimal degrees are the standard for most digital mapping tools (Google Maps, GPS devices, GIS software) because they are easy to compute with. However, degrees-minutes-seconds is still widely used in:

• Paper maps and nautical charts – many printed maps show grid lines in DMS.
• Astronomy – right ascension is measured in hours, minutes, and seconds (though that is a different system, see below).
• Aviation and marine navigation – some radio beacons and nautical publications use DMS.
• Surveying and property boundaries – legal land descriptions often use DMS.

Knowing how to convert lets you read old maps, communicate coordinates with people who use DMS, and check your GPS against a printed source.

Common Mistakes and Pitfalls

Several errors are easy to make when converting:

• Forgetting the sign: Decimal degrees are negative for south latitudes and west longitudes. When converting, you must drop the sign for the DMS value, then add the correct hemisphere letter. For example, -122.4194 becomes 122° 25′ 9.84″ W, not -122° 25′ 9.84″.
• Mixing up minutes and seconds: Each degree has 60 minutes, each minute has 60 seconds. It is not a decimal system. 1.5 minutes is 1 minute and 30 seconds, not 1 minute and 50 seconds.
• Rounding too early: If you round the fractional part of degrees to two decimals before multiplying by 60, you will get a slightly different result. Always carry full precision until the final step.
• Using the wrong direction: Latitude can be N or S, longitude can be E or W. A common mistake is to label a negative longitude as “W� but then also label a negative latitude as “W� – latitude never uses E/W.

How to Choose the Right Format

Which format you should use depends on your task:

• Digital mapping and GPS: Use decimal degrees (DD). Most software and devices accept DD directly. If you enter DMS, you often have to convert it to DD first.
• Printed maps and charts: Use DMS if the map’s grid is labeled that way. You can read the coordinates directly.
• Astronomy (right ascension): This is a different conversion. Right ascension is measured in hours (0–24), not degrees (0–360). To convert right ascension from hours to degrees, multiply by 15 (since 24 hours = 360°). The calculator here is for latitude/longitude, not for right ascension.
• Data exchange: Some file formats (like GPX) use decimal degrees, others (like some KML) can use DMS. Check the specification of the format you are using.

For most everyday use, decimal degrees is the simplest and least error-prone. DMS is mainly for reading or writing coordinates on paper.

Limitations of the Conversion

This conversion is purely mathematical – it does not account for the shape of the Earth or map projections. The same decimal degree value always converts to the same DMS value, regardless of where you are on the globe. However, the physical distance represented by a degree of longitude varies with latitude (it is about 111 km at the equator, but zero at the poles). That is not a problem for this calculator because it only changes the format, not the location.

Another limitation: the calculator assumes you are using the WGS84 datum (the standard for GPS). If you are using a different geodetic datum (like NAD27), the same coordinates may represent a slightly different point on the ground. The conversion from DD to DMS is unaffected by datum, but the original coordinate values are datum-dependent.

Finally, the calculator does not handle the “hours� part of the title question in the astronomical sense. If you meant “convert latitude/longitude to hours, minutes, seconds of right ascension,� that is a different calculation that also requires the date and time to account for the Earth’s rotation.

Frequently Asked Questions

What is the difference between decimal degrees and degrees, minutes, seconds?

Decimal degrees express a coordinate as a single number (e.g., 37.7749°). Degrees, minutes, seconds break that number into three parts: whole degrees, whole minutes (1/60 of a degree), and seconds (1/3600 of a degree). Both represent the same angle, just in different notation.

How do I convert DMS to decimal degrees?

To go the other way, divide the seconds by 3600 and the minutes by 60, then add them to the degrees. For example, 37° 46′ 29.64″ = 37 + 46/60 + 29.64/3600 = 37.7749°. If the direction is S or W, make the result negative.

Why are there 60 minutes in a degree?

This comes from the ancient Babylonians, who used a base-60 (sexagesimal) number system. They divided a circle into 360 degrees, and each degree into 60 minutes, each minute into 60 seconds. The system has persisted because 60 is divisible by many numbers (2, 3, 4, 5, 6, 10, 12, 15, 20, 30), making calculations easier.

Can I use this calculator for right ascension in astronomy?

No. Right ascension is measured in hours, minutes, and seconds of time, where 24 hours equals a full circle (360°). To convert right ascension hours to degrees, multiply by 15. For example, 2 hours = 30°. This calculator is for latitude and longitude only.

What is the precision of one second of latitude?

One second of latitude is about 30.9 meters (approximately 101 feet). One second of longitude varies with latitude: at the equator it is also about 30.9 meters, but at 45° latitude it is about 21.8 meters, and at the poles it is zero.

Why does my GPS show decimal degrees but my map shows DMS?

Many GPS devices and apps default to decimal degrees because they are easier to compute and display. Paper maps and some older navigation equipment use DMS because it was the standard before digital displays. You can usually change the format in the device settings.

Related

• Minutes to Quarter Hours Conversion
• Minutes to Hours: Quick Conversion & Formula
• Minutes to Hours Equation: Simple Conversion

in d | Decimal degrees | ° | 37.7749 | -180
out dms | Degrees, minutes, seconds | ° ′ ″ | d | 2
out dir | Direction | - | (d >= 0 ? "N/E" : "S/W") | 0