Ground sampling distance (GSD)

How much ground each pixel covers, and the image footprint, from the camera and height above ground; catches 35 mm-equivalent focal lengths entered by mistake.

Go the other way: Height for a target GSD →

Planning and education aid. Not for primary navigation. Full disclaimer

Computing your own values needs JavaScript and WebAssembly. The worked example below was computed when this page was built, and the documentation under "How we got this" applies.

2.741cm

Each pixel covers 2.741 cm of ground, and one image spans 150 m across track.

Footprint across track
GSD along track
Footprint along track
Focal length used

Provenance

Computed by: drone.photogrammetry.gsd 1.0.0, core 0.1.0
Model: GSD = sensor width × height / (focal length × image width)
Accuracy: Exact for a nadir view over flat ground at the given height; real GSD varies with terrain and lens distortion
Notes: None
Cites: Wolf, P. R., Dewitt, B. A., and Wilkinson, B. E., McGraw-Hill, Elements of Photogrammetry with Applications in GIS

Something look off?

Your values

Showing an example. Change anything.

Height above ground Like 100 m AGL · plain numbers mean m Sensor width Physical width, like 13.2 mm for a 1-inch sensor · plain numbers mean mm Focal length Physical focal length, like 8.8 mm · plain numbers mean mm Image width Pixels across the long side, like 5472

More options 4

Sensor heightoptional Physical height, like 8.8 mm (for along-track values) · plain numbers mean mm Image heightoptional Pixels on the short side, like 3648 Focal length typeoptional physical (default) or equivalent-35mm Crop factoroptional Needed with a 35 mm-equivalent focal length, like 2.7

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How we got thisFormula, worked example, sources, and proof

Model: GSD = sensor width × height / (focal length × image width)

Show your work

Pixel pitch
pitch = sensor width / image width
13.2 mm / 5,472 px = 2.412 µm
Footprint across track
footprint = GSD × image width
2.741 cm × 5,472 px = 150 m
Ground sample distance
GSD = pitch × height / focal length
2.412 µm × 100 m / 8.8 mm = 2.741 cm

The same steps an agent gets from the MCP server with explain: true.

Accuracy: Exact for a nadir view over flat ground at the given height; real GSD varies with terrain and lens distortion

When to use this: Use this when you know the height you can fly and want to know what resolution the imagery will have: it gives the ground each pixel covers and the footprint of one image, across and along track. That footprint is what overlap, line spacing, and photo interval are computed from, so it is the starting point for the rest of the mission plan.

Limitations: It describes a nadir view over flat ground at one height with an undistorted lens. Terrain relief changes the ground sampling distance across the frame, oblique views change it more, and lens distortion and the processing pipeline move the final product's resolution away from this number. The sensor width and true focal length are the camera's own; a 35 mm-equivalent focal length entered here is caught rather than used.

Worked example: A 1-inch 20 MP camera at 100 m. Source: add-drone-suite scenario: 2.741 cm/px, 150.0 m across track. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.

You enter

Focal length: 8.8 mm
Height above ground: 100 m
Image height: 3648
Image width: 5472
Sensor height: 8.8 mm
Sensor width: 13.2 mm

You get

GSD: 2.741 cm
Footprint across track: 150 m
GSD along track: 2.741 cm
Footprint along track: 100 m
Focal length used: 8.8 mm

Review: Not yet independently reviewed by a Part 107 remote pilot.

Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.

Status: version 1.0.0, core 0.1.0. See this tool in the verification report.

Changes

2026-09-19, changed: Ground sampling distance and height for a target GSD are now stable. Both match a published worked example (a 1-inch camera at 120 m gives 3.13 cm per pixel) and 20 vectors each from a separate implementation. Results are unchanged. Changelog

Checked against: 22 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources

Elements of Photogrammetry with Applications in GIS, Wolf, P. R., Dewitt, B. A., and Wilkinson, B. E., McGraw-Hill, 4th edition. Chapter 6 (vertical photographs: scale and ground coverage). Read free.

Terms

GSD: ground sampling distance: The ground width one image pixel covers, such as 2 cm per pixel. A smaller GSD shows more detail. Source: Elements of Photogrammetry with Applications in GIS

Learn the concept: Photo overlap and flight lines explained, What is ground sample distance (GSD)?