I am wanting to know how do you calculate the curvature distance a fold line may produce based on paper thickness?

For instance I am wanting to do artwork on a thick paper stock and I want to make sure my artwork is within the folds instead of perhaps very close to it. As what I am doing is on small thick boxes, it is critical that I can work this out.

Many thanks.


1 Answer 1


Length of a perfect circular fold for 180 degree turn is π × W:

         corner fold

Image 1 Corner shift

In practice thus you have some slack to the inner side, so W is actually width of paper plus how much inner radius you use. So W is somewhere between 1-2 times the width of the card stock. and the amount of paper that the corner eats is:

         π × 1-2 × w × a/180

where a is the angle of your corner, and w is the width of your cardstock. A value 2 might be pushing it i have never needed to measure card stock this accurately so i allays used a value of 1, but i do regularly accurate sheet metal work which is similar tech. So this is the theoretical underpinning.

Ultimately: Ask your printer.

  • Thanks for the reply however I am a bit confused. What it 'TT' symbol? And what is 'a', this is the radius of the angle? Could you give me an example and your calculation so I can see how you calculate it so I can replicate it as its easier to see it in example since geometry is not my strongsuit since I finished it at school 20 years ago :( Thanks again.
    – Ninjab
    Commented Mar 26, 2015 at 14:19
  • It's not "TT" it's a π symbol which = Pi
    – SaturnsEye
    Commented Mar 26, 2015 at 14:27
  • @Ninjab the "TT" is the greek letter pi which is a mathematical constant. a is the angle of your fold if you have a full fold it would br 180 degrees if its the side of a box it would most likely be 90. w is the width of your cardstock
    – joojaa
    Commented Mar 26, 2015 at 15:20
  • Heh yeh I realied after I posted it cause I recognised pi with the curves. Thanks. However how do I work out this calculation. For instance could you show me an example you would use to work it out. I am not that mathematically gifted. Thanks.
    – Ninjab
    Commented Mar 27, 2015 at 8:20
  • @Ninjab NP, assume you want to fold a 90 degree turn then you would calculate 3.14159*1.1* Width of card*90/180 this is the amount of paper you loose in the fold. Im allowing for not a operfect fold hece 1.1 .
    – joojaa
    Commented Mar 27, 2015 at 8:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.