Camera
Pick a verified drone preset or enter custom camera specs. Focal length must be the actual focal length in mm (not the 35mm equivalent).
Preset sources: Mini 4 Pro — 1/1.3″ CMOS 48MP (8064×6048), FOV 82.1°, 24mm equiv (DJI official specs); sensor 9.68×7.26mm from 1.2µm pixel pitch; actual focal ≈6.94mm derived from DJI FOV. Mavic 3 — 4/3 CMOS 20MP (5280×3956), 12.29mm (DJI official specs). Phantom 4 Pro — 1″ CMOS 20MP (5472×3648), 8.8mm (DJI official specs).
1 · Ground sample distance
GSD = (flight height × sensor width) / (focal length × image width)
2 · Max flight height for target GSD
Reverse: highest you may fly while still achieving the target ground sample distance.
3 · Ground footprint per photo
Width = GSD × image width, height = GSD × image height.
4 · Mapping flight planner
From front/side overlap to photo spacing, flight-line spacing and photo count for a survey area.
5 · Drone preset comparison
Computed GSD at 100 m AGL for each verified preset (same formula, same height).
| Drone | Sensor | Focal (actual) | Image | GSD @100 m |
|---|---|---|---|---|
| DJI Mini 4 Pro | 1/1.3″ CMOS, 9.68×7.26 mm | 6.94 mm | 8064×6048 | 1.73 cm/px |
| DJI Mavic 3 | 4/3 CMOS, 17.3×13.0 mm | 12.29 mm | 5280×3956 | 2.67 cm/px |
| DJI Phantom 4 Pro | 1″ CMOS, 13.2×8.8 mm | 8.8 mm | 5472×3648 | 2.74 cm/px |
Sources: DJI official specifications (Mini 4 Pro user manual & spec sheet; Mavic 3 spec sheet; Phantom 4 Pro spec sheet). Mini 4 Pro sensor dimensions from 1.2µm pixel pitch × 8064×6048; actual focal ≈6.94mm derived from DJI's published 82.1° FOV.
The GSD formula
GSD = ( H × Sw ) / ( f × Iw )
H = flight height above ground (m) · Sw = sensor width (mm) · f = actual focal length (mm) · Iw = image width (px). Result in m/px; ×100 for cm/px. This is the standard similar-triangles relation used in UAV photogrammetry (e.g. Remote Sensing 2025, eq. 1). Pixel size on the sensor is simply Sw / Iw (e.g. Mini 4 Pro: 9.68mm / 8064px ≈ 1.2µm); invert the ratio for a pixel size on ground calculator.
Scope note: this tool covers ground sample distance and mapping flight geometry for drone photogrammetry. For exposure and ND-filter math on drone video, use our ND Filter Exposure Suite; for converting pixels to physical print sizes, see Pixels ↔ Inches Conversion.
Frequently asked questions
What is ground sample distance (GSD)?
Ground sample distance (GSD), also called ground sampling distance, is the real-world size of a single image pixel measured on the ground. A GSD of 2 cm/px means each pixel in your drone photo covers a 2 × 2 cm square of ground. Smaller GSD means finer detail: 1 cm/px resolves small cracks and markings, while 10 cm/px only shows large features. Enter your numbers above to use this page as a ground sampling distance calculator.
What is the formula to calculate GSD?
The standard photogrammetry formula is GSD = (flight height × sensor width) / (focal length × image width). Use consistent length units for sensor width and focal length (both in mm) and flight height in meters; the result is in meters per pixel, multiply by 100 for cm/px. This matches the equation published in the peer-reviewed UAV mapping literature (e.g. Remote Sensing 2025) — the same equation inside every photogrammetry GSD calculator. For how to calculate ground sample distance by hand, work the example in Mode 1 with your own numbers.
How do I calculate GSD for a drone camera?
Enter your camera's sensor width (mm), actual focal length (mm), image width (pixels) and flight height above ground (m) into Mode 1 of this drone GSD calculator. For example, a DJI Mini 4 Pro (9.68 mm sensor, 6.94 mm lens, 8064 px) flown at 100 m gives about 1.73 cm/px. Or pick a drone preset to fill the specs automatically. It doubles as a DJI GSD calculator — override the preset values if you fly another model. To calculate GSD drone operators need just four numbers: sensor width, focal length, image width and flight height.
What GSD do I need for drone mapping and surveying?
It depends on the deliverable: about 1–2 cm/px for detailed inspection, crack detection or small-feature mapping; around 2–5 cm/px for general topographic surveying and orthomosaics; 5–10+ cm/px is enough for large-area reconnaissance. Lower GSD needs lower flight height or a longer focal length, which increases flight time and photo count. Use this drone mapping GSD calculator in Mode 1 to check a planned altitude, or as a drone survey resolution calculator when writing flight specifications.
How high should I fly to get a target GSD?
Use Mode 2 (reverse): maximum flight height = (target GSD × focal length × image width) / sensor width. For example, a DJI Mavic 3 (17.3 mm sensor, 12.29 mm lens, 5280 px) needs to fly no higher than about 75.0 m to achieve 2 cm/px. Flying lower than the maximum gives an even smaller (better) GSD. Mode 2 is effectively a GSD to flight height calculator: set the resolution, get the ceiling.
Why must I use the actual focal length, not the 35mm equivalent?
The GSD equation is a physical similar-triangles relationship, so the focal length must be the real optical distance from lens to sensor in mm. The 35mm-equivalent focal length (e.g. 24 mm on most DJI drones) is a field-of-view convention, not a physical measurement — plugging it in gives a wrong GSD. This calculator's presets already store the true focal lengths (Mini 4 Pro ≈ 6.94 mm, Mavic 3 12.29 mm, Phantom 4 Pro 8.8 mm).
What is the difference between GSD and image resolution (megapixels)?
Megapixels count how many pixels the image has; GSD tells you how big each of those pixels is on the ground. Two 20 MP cameras can give very different GSDs if their sensor sizes, focal lengths or flight heights differ. For the related concept of converting between pixels and physical print/screen sizes, see our pixels to inches converter.
Does a bigger sensor automatically give a better (smaller) GSD?
No. From the formula, GSD improves with a wider sensor only if focal length and image width stay the same — but bigger-sensor cameras usually pair with longer lenses. Compare at the same 100 m height: the DJI Mavic 3 (4/3 sensor) gives ≈ 2.67 cm/px while the smaller-sensor Mini 4 Pro gives ≈ 1.73 cm/px, because the Mini's shorter 6.94 mm lens and 8064 px width dominate. Always compute the full equation rather than judging by sensor size alone.
How do front overlap and side overlap work in drone mapping?
Front (forward) overlap is the shared area between consecutive photos along one flight line; side (lateral) overlap is the shared area between adjacent flight lines. Photogrammetry software needs this redundancy to stitch images and reconstruct 3D geometry. Higher overlap improves reconstruction quality but means tighter photo spacing and more images — Mode 4 of this calculator converts your overlap percentages into exact photo spacing and line spacing, acting as a drone overlap calculator mapping professionals use to lock in 80/70 coverage.
What overlap percentages should I use for photogrammetry?
The widely used starting point is 80% front overlap and 70% side overlap for nadir mapping missions. Use higher values (85/75 or more) over forests, uniform fields, or featureless terrain where matching points are hard to find. Lower overlap (70/60) can work over urban areas with rich texture, but risks gaps in the reconstruction.
How do I calculate the ground footprint of one drone photo?
Multiply GSD by the image dimensions: footprint width = GSD × image width, footprint height = GSD × image height. Mode 3 does this automatically. Example: a Mavic 3 at 75 m (2 cm/px, 5280 × 3956 px) covers about 105.6 × 79.1 m per photo. In other words, Mode 3 is a ground footprint calculator for drone photos: it takes the GSD and multiplies it by the image dimensions automatically — a ground footprint calculator drone photo planners can use before takeoff, doubling as a cm per pixel drone calculator.
How many photos do I need to map a survey area?
Mode 4 (flight planner) computes it: photo spacing along-track = footprint height × (1 − front overlap), line spacing = footprint width × (1 − side overlap), then lines = ceil(area length / line spacing) and photos per line = ceil(area width / photo spacing). Example: a 200 × 150 m area at 80/70 overlap with the Mavic 3 footprint above needs 5 lines × 13 photos = 65 photos. The flight line spacing calculator drone mappers need is built into Mode 4: it derives the line spacing from your side-overlap setting.
Will the 48MP mode on the DJI Mini 4 Pro halve my GSD?
On paper, 8064 px vs 4032 px halves the computed GSD — and this calculator's preset uses the full 8064 px width. In practice the Mini 4 Pro uses a Quad Bayer sensor, so true resolved detail in 48MP mode is less than a native 48MP sensor would deliver; treat the 48MP GSD as a best case. The 12MP binned mode gives cleaner images with double the GSD.
Is GSD measured from ground level (AGL) or sea level?
Always above ground level (AGL) — the height of the drone above the terrain being photographed, not altitude above sea level. Over hilly terrain the true GSD varies with the ground elevation under each photo; plan with the highest ground point in the survey area to guarantee your target GSD everywhere.
Which drone gives the best GSD: Mini 4 Pro, Mavic 3, or Phantom 4 Pro?
At the same 100 m flight height this calculator gives: Mini 4 Pro ≈ 1.73 cm/px, Mavic 3 ≈ 2.67 cm/px, Phantom 4 Pro ≈ 2.74 cm/px. The Mini 4 Pro wins on pure GSD thanks to its short lens and high pixel count, while the Mavic 3's larger 4/3 sensor captures better dynamic range and low-light detail. Use the table as a Mavic 3 GSD calculator, a DJI Mini 4 Pro GSD reference, or a Phantom 4 Pro ground sample distance comparison — pick presets in Mode 1 to compare any altitude side by side.