How to photo-print a properly-sized reference scale

Back to reference scale page

The goal is to make a photo print with the scale being exactly 10 cm long.

This would be easy if photofinishers printed our images sized perfectly to a 4x6 print, but they don't; it's too difficult to align images exactly with the print boundary. So instead they project the image upon an area slightly larger than the print. That means we need to check the length of the scale on the print.

When the print is received, use a ruler to measure the 10cm scale on the print as accurately as possible (you should be able to estimate fractions of a millimeter and thus get centimeters to two decimal places, eg., 10.13 cm). If the printed scale is as close as you'd like to 10 cm, you're done! Just use scissors to cut out the scales. Otherwise, you can adjust the image size and reprint it, using the custom image generator below.

Reference scale generator/downloader

Use the buttons below to generate and download a reference scale image file to save on your computer/device. Send the image file to a photofinisher for printing as a 4x6 inch print. Matte finish reduces glare and fingerprints.

Standard size

Choose this if you haven't already tried printing a scale.

Custom size

Choose this if you printed a scale and it was not exactly 10 cm.

Suggestion: Prints are inexpensive, so rather than sending just one file to the photofinisher, perhaps send several, each a slightly different size, to increase the chance that one of them will be printed with a scale exactly 10 cm. For example, to make three files with scales differing by one millimeter, use 'custom size' with these pairs of values:


(The width of 3141 px is the 'standard size', thought to be most likely to result in a 10 cm print.)

Photofinisher printing machines are usually stable, so when you get one well-sized, it will probably reprint at that photofinisher without need for further adjustment (assuming all machines at that service are set up similarly).

The red 'arrows' are cropping indicators; they provide information, just for interest, about how much of the image was cropped by the photofinisher. Their scale is in pixels.

If you are using a desktop printer (rather than sending the file to a photofinisher), try the 'standard-size' image printed with a DPI setting of 508 dots/inch = 200 dots/cm.

Use scissors to cut the reference scales from the print along the guide lines and at the base of the millimeter scale.

Comments? How'd it go? How close to 10.00 cm was the 'standard size' printed for you?

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Copy of generated reference scale image file