Zerdly

Drone GSD Calculator

Ground sample distance on both image axes from the physical camera geometry and camera-to-ground height, with terrain and motion-blur checks.

100% FreeRuns in your browserIntermediate
How to use this calculator

Inputs

Ground sample distance on both image axes from the physical camera geometry and the camera-to-ground height.

Camera

The lens's real focal length, not its 35 mm-equivalent figure.

Height

Above the ground being imaged — not above sea level, not above the launch point. With a terrain range below, H is above the LOWEST ground.

More options
Terrain range (constant flight elevation)
Motion blur (optional)

e.g. 0.001 s for 1/1000.

Enter the values and press Calculate.

Or load an example to see a worked result.

Pinhole geometry: sensor, focal length, height and footprint
Not to scale — f exaggerated
Pinhole geometry: sensor, focal length, height and footprintSide view: the sensor above the lens, rays through the lens to the ground footprint, with f and H dimensioned, and a small pixel grid.Sensor widthlensfHFootprint W1 px = GSD
Rays through the lens make similar triangles: footprint ÷ H = sensor width ÷ focal length, so W = H × sensor ÷ f and GSD = W ÷ pixels.
Calculate first: a stale result cannot be exported.

Batch from CSV

One row per calculation, with a header row. Values use the units currently selected in the form above. Up to 10,000 rows; nothing is uploaded.

Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.

How to use this calculator

  1. Enter the physical sensor width and focal length (not a 35 mm equivalent) and the image width in pixels.
  2. Add the sensor height and image height for the y axis — without them only the x axis is reported.
  3. Enter the camera-to-ground height, or flight and ground elevations on the same vertical datum.
  4. Optionally add a terrain range, and a speed and exposure time for a motion-blur estimate.

How it works

GSDₓ = H × sensor width ÷ (f × Nₓ) and GSDᵧ = H × sensor height ÷ (f × Nᵧ), in m/px; × 100 for cm/px. The coarser axis is the headline because it limits detail.

H is camera-to-ground height — not sea-level elevation and not height above the launch point. Under a constant flight elevation the coarsest pixel is over the LOWEST ground.

Motion blur ≈ speed × exposure ÷ along-track GSD (straight, uniform motion). GSD is pixel size on the ground, not a measured survey accuracy.

Worked example

13.2 mm sensor, 8.8 mm lens, 5472 px, 100 m. GSDₓ = 100 × 13.2 ÷ (8.8 × 5472) = 0.0274123 m = 2.741228 cm/px (x axis only, because no sensor height was given). The illustrative 36 × 24 mm, 36 mm, 6000 × 4000 camera at 100 m gives 1.666667 cm/px on both axes and a 100 × 66.67 m footprint.

Frequently asked questions

Why must the focal length be physical?

A 35 mm-equivalent figure assumes a full-frame sensor. Using it with the real sensor width gives a wrong GSD, so the tool refuses it rather than guess a crop factor.

Does a smaller GSD mean a more accurate survey?

No. GSD is the ground size of a pixel. Accuracy depends on control, geometry and processing, and is measured with independent checkpoints.

Why do the x and y GSD differ?

When the sensor's aspect ratio differs from the image's pixel aspect (cropping or resizing), the two axes have different ground scales. The tool keeps them separate.

Related tools

Explore more in Surveying, Coordinates, GIS & CAD.

Cite this tool

Zerdly. (2026). Drone GSD Calculator. Retrieved from https://www.zerdly.com/tools/drone-gsd-calculator/

Tip: Enter any known values to calculate the remaining results.

Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.