DMS to Decimal Degrees: How to Convert Coordinates Step by Step

That one line is the whole formula. In practice, however, most mistakes happen in the signs, the separators and the rounding, not in the math. We are Talha Aslan and team, and we do this conversion often when we add location data to business pages, clean up map listings and tidy address lists for clients. So this guide puts the formula, the hemisphere letters, the minus sign, worked examples and the link between decimal places and meters in one place.

If you would rather skip the arithmetic, use our free coordinate converter. It converts between decimal degrees, DMS, degrees decimal minutes and UTM. In addition, the calculation runs entirely in your browser, so the coordinate you type never reaches a server. Still, knowing the formula is the fastest way to sanity check any result a tool gives you.

What does the DMS format actually describe?

DMS stands for degrees, minutes, seconds. It splits an angle the same way a clock splits an hour. One degree has 60 minutes, and one minute has 60 seconds. In other words, one degree holds 3600 seconds. Latitude and longitude are angles measured from the center of the Earth, which is why this base 60 system feels natural for them.

A typical DMS coordinate looks like this: 51°30'02.6"N 0°07'28.7"W. The degree sign (°) marks degrees, the single quote (') marks minutes and the double quote (") marks seconds. Here N means north and W means west. The first value is the latitude; the second value is the longitude.

• Latitude: How far north or south of the equator you are, from 0 to 90 degrees.
• Longitude: How far east or west of the prime meridian you are, from 0 to 180 degrees.
• Minutes and seconds: Both must stay between 0 and 59; a value of 60 or more points to a typo.

Nautical charts, aviation documents, older paper maps and land survey records still lean on DMS. Therefore, when someone hands you a survey plat, a boat log or a printed map, the coordinate will most likely arrive in degrees, minutes and seconds.

Why did decimal degrees become the common language of maps?

Decimal degrees, or DD, write the angle as a single number such as 51.50072. There is no split into minutes and seconds; the fraction is simply part of the degree. As a result, software can store, compare and calculate with a coordinate as one plain number.

For example, RFC 5870, the document that defines the geo URI for sharing locations on the internet, writes latitude and longitude in decimal degrees on the WGS84 reference system. The same document marks south latitudes and west longitudes with a leading minus sign. Web maps, phone location services and structured data markup follow largely the same logic.

Decimal degrees have one more advantage: they need no letters. North and east are positive, south and west are negative, so a pair like 51.50072, -0.12464 carries its direction inside the numbers. That is why decimal degrees cause the fewest surprises when you move data between systems. In short, DMS suits human readers, while decimal degrees suit machines.

What are degrees decimal minutes, and why do people mix them up with DMS?

Degrees decimal minutes, often shortened to DDM or DMM, keep the degrees whole but write a fraction of a minute instead of seconds. For instance, N 51° 30.044' means 51 degrees and 30.044 minutes. GPS units, some marine navigation screens and geocaching apps like this format.

The confusion is easy to see. Take 51° 30.5' and 51° 30' 05". They look alike, yet they are not the same point. In the first, half a minute equals 30 seconds. In the second, there are only 5 seconds. That gap of 25 seconds of latitude works out to several hundred meters on the ground.

Converting DDM to decimal degrees is even simpler: add the minutes divided by 60 to the degrees. Worked example: 51 + 30.044 / 60 = 51.50073. So you reach the same point by a third route. Whenever you see this format, check for a missing seconds mark and a decimal point inside the minutes.

What is the DMS to decimal degrees formula?

The DMS to decimal degrees formula fits on one line: decimal degrees = degrees + minutes / 60 + seconds / 3600. You divide minutes by 60 because a degree has 60 minutes. Likewise, you divide seconds by 3600 because a degree has 60 × 60 = 3600 seconds.

The last step is the sign. If the point lies in the southern hemisphere or west of the prime meridian, you make the result negative. Leave this step until the very end. The minus sign belongs to the whole number, not only to the whole degrees. Follow this order and you will avoid most errors:

1. Write down degrees, minutes and seconds separately, and note the hemisphere letter.
2. Divide the minutes by 60.
3. Divide the seconds by 3600.
4. Add the three values.
5. If the letter is S or W, put a minus sign in front of the total.
6. Round to the precision you need; five or six decimal places usually suffice.

Once this order becomes a habit, a basic calculator gets you there in seconds. On the other hand, if you have dozens of points, jump to the spreadsheet section further down.

Worked example: how do you convert DMS to decimal degrees for a London point?

As an example scenario, take 51°30'02.6"N 0°07'28.7"W. We convert the latitude first and the longitude second. The latitude is north, so it stays positive. The longitude is west, so it will turn negative.

Latitude: 51 + 30 / 60 + 2.6 / 3600. Here 30 / 60 equals exactly 0.5. Next, 2.6 / 3600 equals about 0.0007222. The total is 51.5007222, which rounds to 51.50072 at five places.

Longitude: 0 + 7 / 60 + 28.7 / 3600. Here 7 / 60 equals about 0.1166667. Then 28.7 / 3600 equals about 0.0079722. The total is 0.1246389. Because the letter is W, the result becomes -0.12464.

So the decimal coordinate is 51.50072, -0.12464. Paste it into a map search box and you should land on the same spot. Notice the trap in this example: the degree part of the longitude is zero. You cannot write "-0" degrees and expect every tool to keep the sign. That is exactly why the sign has to apply to the full decimal result, not to the degree field.

Where does the minus sign go for south and west coordinates?

The minus sign always goes in front of the whole number. Take 22°54'30"S 43°10'45"W as an example scenario. For the latitude, 22 + 54 / 60 + 30 / 3600 = 22.908333. The letter is S, so the result is -22.908333. For the longitude, 43 + 10 / 60 + 45 / 3600 = 43.179167, and the letter W gives -43.179167.

The most common error is to apply the minus only to the degrees and then add the minutes and seconds as positive values. That gives -22 + 0.908333 = -21.091667. This number sits about 1.8 degrees further north, well over a hundred miles away. So calculate the absolute value first, then add the sign at the end.

Some sources also put a minus sign in DMS notation, such as -22°54'30". The rule stays the same: the minus applies to the degrees together with their minutes and seconds. Also, if a coordinate shows both a minus sign and an S or W letter, you risk a double negative. When you see that, go back to the source and confirm what the author meant.

What do the N, S, E and W letters change?

The letters replace the sign. N marks north and S marks south for latitude. E marks east and W marks west for longitude. In German sources you may also see O for Ost, which means east, and in Turkish sources you may see K, G, D and B.

• N: Northern hemisphere, positive latitude.
• S: Southern hemisphere, negative latitude.
• E: East of the prime meridian, positive longitude.
• W: West of the prime meridian, negative longitude.

Here is a quick rule of thumb. The entire contiguous United States sits north of the equator and west of the prime meridian. Therefore, every US address should have a positive latitude and a negative longitude. If a US location shows a positive longitude, the sign was most likely dropped during conversion.

Likewise, in the UK the longitude can be positive or negative, because the prime meridian runs through Greenwich. Points in the east of England sit east of it, while most of the country sits west of it. That makes the sign check even more important for British data.

How do you convert decimal degrees back to DMS?

Going back reverses the steps and takes three moves. First, take the whole number as degrees. Next, multiply the fractional part by 60; the whole number of that result is the minutes. Finally, multiply what is left by 60 again to get the seconds.

Worked example: convert 51.50072 back. The whole number is 51, so 51 degrees. Then 0.50072 × 60 = 30.0432, so 30 minutes. What remains is 0.0432 × 60 = 2.592, which rounds to 2.6 seconds. The result is 51°30'02.6"N, right where we started.

For a negative value, split off the sign first. For -0.12464, work with 0.12464 and add W at the end. Multiplying the fraction of a negative number directly invites sign errors. In addition, if you only need degrees decimal minutes, stop after the second move: 0° 07.478' W.

How do you convert coordinates with our tool?

Doing the DMS to decimal degrees math by hand teaches the method, yet for daily work a tool is faster and safer. With our converter the process looks like this:

1. Open the coordinate converter tool and stay in the "Convert" mode.
2. Type or paste your coordinate into the box, for example 51°30'02.6"N 0°07'28.7"W.
3. The tool recognizes the format and shows decimal degrees, DMS, decimal minutes and UTM at once.
4. Read the precision line to see roughly how many meters your source can resolve.
5. Copy the format you need, or use "Open in maps" to check the point on a map.

The converter also reads hemisphere letters, comma decimals and map links. Moreover, if the latitude comes out above 90, it tells you the latitude and longitude may be swapped. These small warnings save you from a pin that lands in the wrong country. Note that the tool works with WGS84; national grids and cadastral systems are out of scope.

How many decimal places do you need for accuracy?

The number of decimal places sets how small an area your coordinate points to. According to the USGS answer on degree distances, one degree of latitude equals about 69 miles, or roughly 111 km. The same source puts one minute at about 6,068 feet and one second at about 101 feet, or roughly 31 meters. The table below derives approximate values from that figure:

In practice, five places are enough to mark a shop entrance. However, RFC 5870 reminds us that the number of digits alone does not measure accuracy. If your phone located you within 20 meters, writing eight decimals will not make the point any better.

Why is one degree of longitude not the same length everywhere?

Lines of longitude, called meridians, meet at the poles. So the distance between two meridians is widest at the equator, shrinks as you move north or south and falls to zero at the poles. USGS makes the same point: a degree of latitude stays fairly constant, while a degree of longitude varies greatly toward the poles.

For a quick estimate, multiply the length of one degree of latitude by the cosine of your latitude. Worked example: London sits at about 51.5 degrees north, and cos 51.5° is about 0.62. So one degree of longitude there is roughly 111 × 0.62 ≈ 69 km, or about 43 miles. At 60 degrees, cos 60° = 0.5, so the same degree drops to about 56 km.

In practical terms, the meter values in the table apply along latitude. Along longitude, the same number of decimals covers a somewhat smaller distance. For everyday pins this does not matter. For distance math, though, it matters a lot, which is why our converter offers a separate two point mode.

How many decimals should structured data on a business page use?

In its local business structured data documentation, Google asks for at least five decimal places in the latitude and longitude of the geo property. So a shortened value like 51.501 does not meet that guidance, while 51.50072 does. The property is recommended rather than required. Still, if you add it, add it correctly.

If your coordinate arrives in DMS, run the DMS to decimal degrees formula above, then round to at least five places. One caution: a DMS value with whole seconds, such as 02", only resolves to about 31 meters. Converting it to five decimals looks precise on paper but does not sharpen the actual point. The better move is to drop a pin on the entrance and copy the coordinate again.

We explain the bigger picture in our schema markup guide. You can also build the markup with our schema generator instead of writing it by hand. Keep in mind that map visibility depends on far more than a coordinate; our Google Maps SEO guide covers the rest.

Which coordinate formats does Google Maps accept?

The Google Maps Help page on coordinates shows three formats you can type into the search box: degrees, minutes and seconds; degrees and decimal minutes; and decimal degrees. It also lists a few formatting rules. Use a period as the decimal separator, not a comma. Enter the latitude before the longitude. Finally, keep the first number of the latitude between -90 and 90 and the first number of the longitude between -180 and 180.

Comma decimals are the classic problem when data comes from European spreadsheets. A string like 51,50072, -0,12464 can turn into four separate numbers. Before pasting, switch the decimal separators to periods and leave a single comma between the two values.

For the opposite direction, copying a point's coordinates out of the map, see our guide on how to find coordinates in Google Maps. The decimal value you copy there converts into any other format with the method in this article.

What are the most common conversion mistakes?

Over the years of cleaning client data, we have seen the same mistakes again and again. The list below helps you work out why a converted point landed in the wrong place:

• Swapped latitude and longitude: Writing -0.12464, 51.50072 drops the pin somewhere completely different.
• Minus on the degrees only: On south and west values this shifts the point by a long way.
• Dividing minutes by 100: Reading 30'02" as 0.3002 is a classic decimal habit error.
• Mixing up DMS and DDM: Reading 30.5 minutes as 30 minutes and 5 seconds moves the point.
• Comma decimals: Most maps and software expect a period.
• Rounding too early: Rounding to two places in the middle of the math ruins the result at the kilometer level.

The easiest way to catch these is to open the result on a map and look. For instance, if a London office pin lands in the North Sea or in another city, one of the items above is almost certainly to blame.

What do you do when seconds round up to 60?

When you convert decimal degrees back to DMS, the seconds sometimes come out as 59.99. Round that to one place and you get 60.0; however, seconds cannot equal 60. In that case, set the seconds to 0 and add one to the minutes. If the minutes then reach 60, set them to 0 and add one to the degrees.

Worked example: imagine converting 51.0166664. The fraction 0.0166664 × 60 = 0.999984 minutes, so 0 minutes. Next, 0.999984 × 60 = 59.99904 seconds, which rounds to 60.0 at one place. The correct notation is 51°01'00.0", not 51°00'60.0".

This looks minor, but it often trips up automated systems. Some software rejects a value with 60 seconds as invalid. Others quietly misread it. So if your own spreadsheet or script outputs DMS, always check for this carry. Also, always round in the very last step.

Is every coordinate WGS84, and why does the datum matter?

No, not every coordinate uses the same reference system. Web maps, phones and GPS receivers generally use WGS84, and RFC 5870 also sets WGS84 as the default for geo URIs. Survey records, property documents and engineering drawings, however, may use other datums and map projections.

Why does that matter? The same DMS value written against a different datum can point to a slightly different spot on the ground. Your formula can be perfect, yet if you assume the wrong datum, the result still lands off target on the map. Moreover, that offset is not the same size everywhere.

Our advice is simple. Check which system a document uses, either in the document itself or with the office that issued it. For official survey or property work, have a licensed surveyor confirm the result. Put simply, the formula in this guide changes the angle format; it does not change the datum. Our converter also works in WGS84 only.

How do you batch convert DMS to decimal degrees in Excel or Google Sheets?

If you have dozens of branches or points, converting DMS to decimal degrees one by one gets tiring. Put degrees, minutes and seconds in separate columns, write the formula once and fill it down. For instance, with degrees in column A, minutes in column B and seconds in column C, the decimal degrees formula is =A2+B2/60+C2/3600.

We recommend a separate column for the hemisphere letter. If the letter is S or W, multiply the result by -1. That way you never type the minus sign by hand on each row. In addition, a direction column prevents the minus on the degrees only mistake, and it handles the zero degree longitude case cleanly.

• If your sheet uses a locale with comma decimals, check the separator before you export.
• Format the result column to show at least five decimal places.
• Spot check a few random rows with the tool or on a map.

With this setup you get a process that is both quick and easy to audit. For example, you can clean the location list of a multi location business in a single afternoon.

How do you verify a converted coordinate?

Do not use a converted value before you check it. This does not take long; the short checklist below catches most errors in a few minutes:

1. Is the latitude between -90 and 90, and the longitude between -180 and 180?
2. Do the signs match the hemisphere letters you started with?
3. Is the latitude written first and the longitude second?
4. Is the decimal separator a period?
5. When you open it on a map, does the pin land on the building you expect?
6. If you convert it back, do you get the original DMS value?

The last item is a particularly strong check. Converting the decimal value back to DMS and comparing it with the source exposes formula and sign errors right away. Also, when you send the result to someone else, state both the format and the reference system.

Why make coordinate conversion a routine?

Converting coordinates looks like a small job. Yet a wrong pin can send a customer to the wrong street, delay a delivery or make the location on a business page look inconsistent. That is why it pays to understand the formula once and then apply it in the same order every time.

To sum up, remember three rules. Divide minutes by 60 and seconds by 3600. Apply the minus sign to the whole number at the end. Round last, and keep at least five decimal places. On top of that, always check the result on a map.

If you plan to add a map to your site, we also looked at the performance side in does embedding Google Maps slow down a website. When you think about location data, structured data and map visibility together, a correctly converted coordinate becomes a small but solid building block of your site.