Aerial Photo Scale Calculator
Computes vertical aerial photo scale from camera focal length and flying height above ground.
Inputs
Vertical-photo scale 1 : n from the actual focal length and the height above ground.
Enter the values and press Calculate.
Or load an example to see a worked result.
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.
How the method works
Fixed example values for illustration — not your result.
How to use this calculator
- Enter the camera's actual (calibrated) focal length in millimetres — not a 35 mm-equivalent figure.
- Give the flying height above ground, or the camera elevation with the terrain elevation (a lowest and highest pair gives a scale range). Or choose the inverse mode to find the flying height for a target scale.
- Optionally enter a distance measured on the original photo to convert it to a ground distance.
- State whether the focal length is the actual one — a 35 mm-equivalent figure is refused because it gives the wrong scale. The similar-triangle diagram labels your values; the batch CSV run handles several heights at once.
How it works
For a vertical photo the scale is focal length over flying height above the ground: scale = f ÷ H, so the denominator is H ÷ f with both in the same units.
In elevation mode H = camera elevation − terrain elevation. Higher ground is closer to the camera, so its scale is larger; a terrain range gives the scale at each end.
Ground distance = photo distance × denominator. Tilt, relief displacement and lens distortion are outside this simple model, and a resized screen image has no known scale.
Worked example
f = 152 mm, H = 1520 m. Denominator = 1520 m ÷ 0.152 m = 10,000, so the photo is 1:10,000 and a 50 mm line is 500 m on the ground. A 20 mm lens at 100 m gives 1:5,000.
Common mistakes
- Using altitude above sea level instead of height above the ground.
- Entering a 35 mm-equivalent focal length for a small-sensor camera.
- Measuring on a zoomed or resized screen image.
Frequently asked questions
Is flying height the same as elevation?
No — use the height of the aircraft above the ground being photographed, not its altitude above sea level. Use the elevation mode to subtract the terrain for you.
Why isn't the scale exact everywhere on the photo?
A central-perspective photo only has one true scale at one ground height; higher ground is closer to the camera (larger scale) and lower ground is smaller. Orthophotos correct for this.
Is this official course material?
No. It is free study support mapped to surveying course levels — not official North Metropolitan TAFE content or advice. Always follow your lecturer and the official assessment brief, and check your own working.
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Cite this tool
Zerdly. (2026). Aerial Photo Scale Calculator. Retrieved from https://www.zerdly.com/tools/aerial-photo-scale-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.