Ground Sample Distance (GSD) Calculator
Find out how much real-world ground one image pixel covers: enter your drone or camera altitude, lens focal length, sensor pixel pitch and image dimensions.
m
mm
μm
px
px
Real-world distance represented by one image pixel
- 1
Numerator (pixel pitch × altitude)
3.76 μm × 120 m = 451.2 - 2
Denominator (focal length × 10)
24 mm × 10 = 240 - 3
Ground Sample Distance
451.2 ÷ 240 = 1.88GSD in cm per pixel — the real-world ground size of one image pixel.
How does this calculator work?
GSD (cm/px) = pixel pitch (μm) × altitude (m) ÷ (focal length (mm) × 10). A 3.76 μm pixel pitch camera at 120 m with a 24 mm lens gives about 1.9 cm/px — enough for accurate mapping. Fly lower or use a longer lens for finer detail; fly higher for faster area coverage.
Formula
How this is calculated
Ground Sample Distance (GSD) is the distance on the ground that one pixel of an aerial image represents. A smaller GSD means higher spatial resolution — objects smaller than the GSD cannot be resolved. The formula derives from simple pinhole-camera geometry: the sensor pixel pitch (physical size of one pixel on the sensor) is scaled by the ratio of flying altitude to focal length, giving the equivalent ground size.
Converting units: pixel pitch in micrometres (μm) and altitude in metres and focal length in millimetres, the factor of 10 in the denominator handles the unit conversion to centimetres per pixel. For GSD in metres divide by an additional 100. The footprint width and height (how much ground a single image covers) are simply GSD multiplied by the number of pixels in each dimension, and area in hectares is footprint width × height ÷ 10 000.
Typical GSD benchmarks for drone mapping: ≤ 1 cm/px for precision surveying (very low altitude or long-focal-length lens), 2–5 cm/px for topographic mapping and volume calculations, and 5–15 cm/px for corridor inspection and broad area surveys. Higher altitude increases GSD (lower resolution); a longer focal length or smaller pixel pitch decreases it (higher resolution). The calculator assumes a nadir (straight-down) view — oblique angles increase effective GSD.
Frequently asked questions
The pixel pitch is in the camera or sensor spec sheet, often listed in micrometres (μm). For many popular drone cameras it is between 1.6 μm and 5 μm. You can also calculate it: sensor physical width (mm) ÷ image width (px) × 1000 gives the pitch in μm.
Industry guidance suggests GSD ≤ 2–3 cm/px for topographic surveys needing centimetre-level accuracy and GSD ≤ 1 cm/px for precision engineering or forensic applications. For general inspection and ortho-mosaics 5–10 cm/px is usually sufficient.
Yes — GSD is directly proportional to altitude. Flying twice as high doubles the GSD (halves resolution). Halving the altitude halves the GSD and quadruples the number of images needed to cover the same area, so there is a trade-off between resolution and survey efficiency.
Also known as
TG we-Calculate Editorial Team. (2026). Ground Sample Distance (GSD) Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/ground-sample-distance-calculator
TG we-Calculate Editorial Team. "Ground Sample Distance (GSD) Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/ground-sample-distance-calculator.
TG we-Calculate Editorial Team, "Ground Sample Distance (GSD) Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/ground-sample-distance-calculator
@misc{wecalculate_ground_sample_distance_calculator, title = {Ground Sample Distance (GSD) Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/ground-sample-distance-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?