How to Calculate Poly Mailer Sizes for Shipping in less than 30 Seconds

Shipping products to customers using poly mailers can save shipping costs and provide a flexible way to wrap the product without needing a bulky or odd-shaped box. Unfortunately, it’s not always clear what size poly mailer to use for a product. Here’s how to calculate poly mailer sizes for shipping.

Once you know what parts of the product to consider and why figuring out what size poly mailer to use is simple. We’ve created the free calculator below to help you determine the right size poly mailer for your product. Not too big, not too small.

Poly Mailer Size Calculator

Here’s a handy calculator to determine the ideal poly mailer size for your next shipment. Input the product’s length, width, and height below.

Our Picks for Poly Mailers and Bubble Mailers

You can also order most of these sizes from your local office supply store–and find smaller quantities in-store for immediate fulfillment needs, but you will likely pay a lot more.

For the odd sizes, try the Scotch Flex & Seal Shipping Roll.

The Formula to Calculate Poly Mailer Sizes

The general formulae for determining poly mail size are these:

Length: product length (in) + product height (in) + 2"
Width: product width (in) + product height (in) + 1/2"

Looking at these two formulas, a pattern emerges and decides the minimum size.

Sticking a product into a poly mailer will stretch its opening. Since a poly mailer itself isn’t stretchable, the maximum amount of surface area it can cover will never change. The product’s height will expand the mailer accordingly. This is why we have the height in both dimensions. The taller the product, the wider the poly mailer needs to be.

We add 2″ to the length to account for the flap and 1/2″ to account for deviations in measurements by manufacturers, extra room for maneuvering the product into the poly mailer, and if we’re using a bubble mailer, specifically, accounting for the thickness of the mailer itself.

READ THIS NEXT: How to save money on USPS shipping.

If, when calculating this on your own, you end up with a 1/2″ result, round up to the next whole inch. Having a too-big mailer is much preferred over a too-small mailer.