Drone Camera Ground Coverage Calculator
A drone camera pointing straight down captures a rectangle of ground whose size is set by the sensor dimensions, the lens focal length and the flight altitude. From the same inputs plus the image pixel count you also get the ground sampling distance: the ground size of a single pixel, which is the resolution that matters for mapping and inspection. This calculator applies the pinhole-camera similar-triangles relationship to return the ground footprint width and height, the total area, and the GSD in centimetres per pixel.
Ground coverage formula
ground width = sensor width * altitude / focal length
ground height = sensor height * altitude / focal length
footprint area = ground width * ground height
GSD (m/px) = (sensor width * altitude) / (focal length * image width)
GSD (cm/px) = GSD (m/px) * 100
Sensor and focal length use the same units (mm); altitude is in metres so the ground footprint is in metres. The pinhole model assumes a nadir view over flat ground.
Drone coverage context
- Footprint scales linearly with altitude; double the height doubles each side and quadruples the area.
- GSD scales linearly with altitude too, so higher flights trade detail for coverage.
- Use the true physical focal length and sensor size, not a 35 mm equivalent.
- The model assumes a straight-down (nadir) view; obliques and terrain change the footprint.
- Mapping missions choose altitude to hit a target GSD while keeping image overlap.
Drone camera coverage: frequently asked questions
What is the ground footprint of a drone camera?
The ground footprint is the rectangular area on the ground captured in one nadir (straight-down) image. Its width equals sensor width times altitude divided by focal length, and its height equals sensor height times altitude divided by focal length. It grows linearly with altitude.
What is ground sampling distance (GSD)?
GSD is the real-world distance represented by one pixel, usually in centimetres per pixel. GSD = (sensor width times altitude) / (focal length times image width in pixels). A smaller GSD means finer detail. It is the key resolution metric for mapping and inspection flights.
How does altitude affect coverage and detail?
Footprint area grows with the square of altitude, so flying twice as high covers four times the ground per image but doubles the GSD (halves the detail). There is always a trade-off between area covered per image and resolution on the ground.
Do I use focal length or 35 mm equivalent?
Use the true (actual) focal length of the lens together with the true physical sensor dimensions, all in the same units (millimetres). Do not mix a 35 mm equivalent focal length with a small physical sensor; that would give the wrong footprint.
Does this assume the camera points straight down?
Yes. The formula assumes a nadir view with the sensor parallel to flat ground. Oblique angles and terrain relief change the footprint shape and require a more complex projection. For typical mapping flights at nadir, this is the standard calculation.
Official sources
- U.S. Geological Survey: aerial imagery and ground sampling distance.
- U.S. Federal Aviation Administration: drone (UAS) operations.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.