How to Measure Distance in a Photo

Written by Darlene Antonelli, MA

Last Updated: January 29, 2024

Did you know that you can take a picture of the layout of an object, then later get its measurements? This wikiHow will teach you how to measure distance in a photo using Adobe's Photoshop on your computer.

Steps

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1
Open Photoshop. You'll find this in your Start Menu or Applications folder.
- If you don't have Photoshop, you can sign up for a free 7-day trial here. You can select a plan ranging from $9.99/mo to $52.99.mo.
You can either go to File > Open within Photoshop, or you can right-click the file in your file browser and select Open with > Photoshop.

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If you don't see this in your Tools menu, click and hold down on the Eyedropper Tool.
4
Click and drag from the starting point of your measurement to the end point. You'll see the ruler between the two points you've clicked. If you want to maintain 45 degree increments, press and hold the ⇧ Shift key as you drag the ruler.
- If you want to add another measurement angle, press Alt (Windows) or ⌥ Option (Mac) and drag your cursor to the other end point. In the case that you've already un-clicked from the last end-point, you can double-click the line to pick it up again.^{[1]
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Question

How do you measure distance in a photo? (This article doesn't actually cover that.)

G Innes

Community Answer

Every fixed lens has a fixed angle of view. Using graph paper or other known target, take a picture. Now you have a reference image that can be overlaid on unknown targets. You will at least get the size as an angle-of-view (in degrees). For example, the moon or the sun is about 0.47 degrees in size. To convert into linear distance, it is necessary to know how far away the target is. Google maps may help for outdoor targets. Clues from geometry in the frame may also help establish distance. For example, a road may have painted markings or signage at known distances or of known size near the target. Sometimes it will be necessary to reconstruct the scene using 3-dimensional software.

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Question

Which drawing program should you use?

G Innes

Community Answer

The freeware OpenOffice has drawing software that is compatible with the text editor and spreadsheet of the same suite. It is more modern than Microsoft Office software, especially using a trackpad. (Zooming is really easy and helps with detailed work.) You can save files in both OpenOffice and Microsoft formats.

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Question

HOW DO YOU GET A REFERECE DISTANCE?

G Innes

Community Answer

Every fixed lens has a fixed angle of view. Using graph paper or other known target, take a picture. Now you have a reference image that can be overlaid on unknown targets. You will at least get the size as an angle-of-view (in degrees). For example, the moon or the sun are about 0.47 degree in size. To convert into linear distance, it is necessary to know how far away the target is. Google maps may help for outdoor targets. Clues from geometry in the frame may also help establish distance. For example, a road may have painted markings or signage at known distances or of known size near the target.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
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