EPSG code is a unique identifier for different coordinate systems. It's a public registry of geodetic datums, spatial reference systems, Earth ellipsoids, coordinate transformations, and related units of measurement. Each entity is assigned an EPSG code between 1024-32767.
EPSG code is very important for us to find the correct location of your coordinates on earth. There are so many different coordinate systems defined for different areas. If you provide it wrong, the coordinates will be mapped to a completely different location.
To find your EPSG code correctly, the most accurate way is to check the coordinate system information on your GPS device, sometimes it won't show the EPSG code directly. Instead, you will have the name and related information of the coordinate system. Normally, the name will be combined with the datum and specific area name. Common datum names would be WGS84, NAD83, and NAD27. Common area names in US would be state plane like state name + zone number, state name + north/east/center, etc. Globally, most common names are UTM with zone number, you can search utm+zone code to find the EPSG.
Then you will get a list of coordinate systems that match the area name. You'll find the 5th result is what we want. You can click that result, you can find the EPSG code at the title.
Be careful of the units, the unit is defined inside the EPSG code, you need to make sure that the EPSG matches with your coordinate units. The above EPSG has units in meter, if you want the unit in feet, you should search California zone 4 ftus instead. Then you'll find NAD83 / California zone 4 (ftUS)
If you have the datum, the area name, and the unit right, you can upload it in our app. You should still check if it's located at the right place.
You can provide the datum and area name information to us if you still couldn't find the code with the above attempt.
If you have no idea of the coordinate system in the GPS device, the only thing you have is some coordinates and images taken by drone, you can also contact us. We'll search in our database to find the best matching EPSG code. However, this approach won't guarantee to be accurate, it will find the possible one, but it may not be the correct one. So it is still recommended to try the approach one first.
Another site to reference based on your state/location is https://spatialreference.org. Here you can search an area which will output a list of codes that may apply to your area plus surrounding areas.
With the search of California, we can see all possible EPSG codes in the state. With the understanding of what zone and datum you are in, you can then match the corresponding EPSG code to that. In cases where there may be two codes listed, click on each as it may say to use one vs another due to and update or error.