Location by Latitude and Longitude

The short answer

Latitude and longitude describe any point on Earth as two numbers. Latitude is the position north or south of the equator, from -90 to +90 degrees. Longitude is the position east or west of the prime meridian, from -180 to +180 degrees. When your vehicle breaks down, reading these two numbers from your phone and passing them on, latitude first, gives a tow operator, roadside assistance provider or emergency dispatcher a point they can enter into a map. That point can still be wrong or vague in some situations, so check it against what you can see around you.

In the contiguous United States, latitude is positive (north) and longitude is negative (west) when written in decimal degrees. If the longitude loses its minus sign, the point moves to the other side of the world. This is one of the most common reasons shared coordinates fail.

Coordinate formats you may see

Phones, map apps and vehicle systems show the same location in different formats. All of the forms below are valid. The person receiving your coordinates needs to know which format you are giving them, so read them out exactly as shown, including any letters or symbols.

Format | How it is written | Notes; Decimal degrees (DD) | Two decimal numbers, e.g. latitude 00.00000, longitude -00.00000 | Easiest to type into a map search box; the minus sign marks south or west; Degrees, minutes, seconds (DMS) | Degrees, then minutes, then seconds, followed by N, S, E or W | The letters replace the minus sign; in the US this is N and W; Degrees and decimal minutes (DDM) | Degrees, then minutes with a decimal, followed by a direction letter | Common on some GPS units and marine or aviation devices

To convert DMS to decimal degrees, use: degrees + (minutes ÷ 60) + (seconds ÷ 3600). Then add a minus sign if the direction is S or W. The layout below shows the structure only. The numbers are placeholders, not a real location.

Decimal degrees: LAT dd.ddddd LON -ddd.ddddd; DMS: LAT dd° mm' ss" N LON ddd° mm' ss" W; Order: latitude first, then longitude

How precise do the numbers need to be?

One degree of latitude is roughly 111 kilometres (about 69 miles). Each extra decimal place therefore narrows the point by about a factor of ten. A degree of longitude covers the same distance only at the equator and gets shorter further north. Across the US, longitude digits represent somewhat less ground than the latitude figures below.

Decimal places | Approximate span in latitude; 2 | About 1.1 km; 3 | About 110 m; 4 | About 11 m; 5 | About 1.1 m

Precision and accuracy are not the same. Five decimal places describe a point down to roughly a metre, but your phone's position fix may be much less accurate than that. Tall buildings, deep cuts in terrain, tunnels, dense tree cover and the inside of a vehicle can all reduce accuracy. A responder can usually work with four or five decimal places in decimal degrees. Sharing every digit your phone shows does no harm.

Step by step: getting and sharing your coordinates after a breakdown

1) Get to safety first. Turn on your hazard lights and move yourself and any passengers away from traffic where it is safe to do so. If anyone is hurt or in danger, call 911 before anything else. 2) Open a map app with location services turned on and wait for your position marker to settle. A fix taken the moment the app opens may be out of date. 3) Display the coordinates. In many map apps, pressing and holding on your position, or dropping a pin, shows the latitude and longitude. Some phones also show coordinates in a compass or similar built-in app. Menus vary by app, version and device, so use whatever your phone offers. 4) Copy the coordinates exactly as shown. Keep the minus sign or the N/S/E/W letters, the decimal points and the order: latitude, then longitude. 5) Share them in writing if you can, by text message or through the provider's app, so nobody has to transcribe digits by ear. If you must read them aloud, say each digit separately and say 'minus' or 'west' clearly. 6) Add context the coordinates cannot carry: road name or route number, direction of travel, nearest exit or mile marker, which shoulder you are on, and your vehicle's make, model, colour and licence plate. 7) Stay reachable and keep your phone charged. If you move the vehicle or walk to a safer spot, send updated coordinates.

Checking that the coordinates are correct

Before you rely on the numbers, paste them back into your map app's search box. The pin should land on the road you are on, close to your marker. Then compare it with what you can actually see. If the pin is on a different road, on the wrong side of a divided highway, in a field far from the roadway or in another state or country, the coordinates have been mistyped or the fix is poor.

Swapped values: latitude and longitude entered in reverse order. Missing minus sign: a US longitude without its minus sign points to the eastern hemisphere. Format mix-up: DMS or DDM numbers typed as if they were decimal degrees, which can shift the point a long way. Dropped or merged digits: especially when numbers are read aloud over a poor connection. Stale fix: the phone reporting an earlier position, such as where it last had a good signal.

Looking up a location from coordinates you were sent

If you are the one going to the stranded vehicle, as a friend, family member or recovery driver, enter the coordinates into a map app's search field. Most major map apps accept decimal degrees separated by a comma, latitude first. Many also accept DMS. Check where the pin lands before you set off. If it looks wrong, ask the sender to confirm the minus sign, the order and the format before you drive anywhere.

Recognizing the right vehicle at the location

Coordinates get you to a point, not to a specific car. On the scene, confirm you have the right vehicle with details the driver gave you, not just its position.

Licence plate and state: the most reliable single identifier. Make, model and colour: useful at a distance, but many vehicles look alike, especially common models in common colours. Hazard lights or other agreed signals: ask the driver to flash lights or confirm by phone as you approach. Direction of travel and shoulder: on a divided highway, the pin can sit between carriageways. Knowing which direction the driver was heading tells you which side to search. Level: where roads cross on overpasses, interchanges or stacked ramps, coordinates alone do not say which level the vehicle is on. Road name and nearby exit resolve this.

Limits to keep in mind

Coordinates do not include height, lane, direction of travel or which roadway of a divided highway you are on. Accuracy depends on your device and surroundings. In the US, wireless carriers may pass location data to 911 automatically. How precise that data is depends on the phone, the carrier and the local 911 system, so give your coordinates and landmarks to the dispatcher anyway. Text-to-911 is not available everywhere. Where it is not supported, you should get a bounce-back message telling you to call.

Some vehicles have connected services or emergency call buttons that can report location on their own. Whether yours does depends on the model year, market, trim and active subscription. Check your owner's manual or the manufacturer's service terms rather than assuming the feature is there. Likewise, not every roadside assistance provider or towing company takes coordinates in the same way. If you have time, ask which format they prefer.

What this guide does not cover

No specific figures for phone GPS accuracy, app menu paths, provider procedures or vehicle telematics features were available for this guide. Apart from the arithmetic relationship between degrees and distance, the steps above rely on general principles of how coordinates work. For exact instructions, check your phone's and map app's help pages, your vehicle documentation and your roadside assistance provider.