How much does shrink plastic shrink?

Polystyrene shrink plastic (like Shrinky Dinks) typically shrinks by about 45% in each direction, so your finished piece is about 55% of the original size. Polyester shrink film shrinks more, around 55% in each direction.

Does shrink plastic shrink evenly?

Most shrink plastic shrinks more or less evenly in both directions, though there can be slight variation. Pre-sanded or printed shrink plastic may shrink slightly less evenly. Always test a small piece first.

How thick does shrink plastic get?

As the plastic shrinks in area it thickens proportionally. A piece that shrinks by 45% in each direction will become roughly 3.3x thicker than the original sheet. Standard 0.3mm sheets become about 1mm thick after shrinking.

Can I adjust the shrink percentage?

Yes. Use Advanced Options to set a custom shrink percentage if your specific material shrinks differently from the default. Always test a sample piece to confirm the exact shrink rate.

CraftCalcs

Shrink Plastic Calculator — Starting Size for Shrink Art

Calculate the starting size to cut your shrink plastic so it shrinks to your desired finished dimensions.

Desired Finished Width

Width measurement

Desired Finished Height

Height measurement

Material Type

Different plastics shrink at different rates

How We Calculate This

This calculator works backwards from your desired finished size, dividing by the remaining percentage after shrinkage to find the starting cut size.

The formula

Starting size = Finished size / (1 - Shrink %)

Thickness multiplier = Scale factor\u00B2

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.