GSD Calculator

Two ways to use it

• Height to GSD. Enter your camera and flying height to get the ground size of one pixel and the area each photo covers.
• GSD to height. Enter the GSD your project needs to get the height to fly at.

Both use the standard formula: GSD = sensor width × height ÷ (focal length × image width). Our guide to ground sample distance explains the formula, worked examples and how to choose a target.

Getting the camera numbers right

Pick your drone from the camera list to fill in the sensor size, image size and focal length. Each preset comes from the manufacturer's published specifications. If your drone isn't listed, enter the values yourself:

• Sensor width and height (mm). Spec sheets usually give a format name instead, such as "1-inch", "1/1.3-inch" or "4/3". The names are historical and don’t match the real size: a “1-inch” sensor measures roughly 13.2 × 8.8 mm, and a 4/3 sensor roughly 17.3 × 13 mm.
• Image width and height (px). Use the resolution you will actually shoot at. Many 48 MP drone cameras shoot 12 MP by default, and the GSD at 12 MP is twice as coarse.
• Focal length (mm). Enter the lens’s actual focal length rather than its 24 mm-equivalent figure. Every photo records it in its metadata, which you can read with the EXIF Viewer.

Small errors in these values produce small errors in the GSD. Swapping the equivalent focal length for the real one, or using the wrong resolution mode, produces large ones.

Height means height above the ground

The height in the calculator is the distance from the camera to the ground below it, not the height shown on your controller. Controllers usually show height above the take-off point. They are only the same over flat ground:

• Take off from a hill and map the valley below, and the camera is further from the ground than the controller shows, so the GSD is coarser than planned.
• Map up a slope at a fixed height above take-off, and the camera gets closer to the ground as you go, so the GSD gets finer and the overlap between images drops.

Use terrain-follow in your mapping app on sloping sites, or plan for the lowest and highest parts of the site separately.

Check your result in the field

After a short test flight, open one photo at 100% and look at something of known size, such as road markings, paving slabs or a car. If the detail you need is clearly visible, the GSD works for the job. If not, fly lower or use a camera with a longer lens.

Staying within the height limit

In the EU and UK the open category limit is 120 m above the ground, and in the US it is 400 ft (about 122 m). If the calculator suggests a height above the limit for your target GSD, you can fly lower than suggested, which gives a finer GSD but more images and a longer flight. Use the Coverage Calculator to see what that costs in flight time.