How many poly mailers should you stock for the holiday peak?

Why does mailer stock matter more in peak than the rest of the year?

Running out of poly mailers stops shipping the same day. Overbuying ties up cash and shelf space. Most of the year a small mistake either way is easy to fix. In the holiday peak it is not: order volume jumps, carriers are busier, and suppliers get more orders at the same time.

The 2026 calendar is tight. Thanksgiving falls on November 26, so Black Friday is November 27 and Cyber Monday November 30. USPS recommends sending Christmas parcels by December 17 (Ground Advantage and First-Class Mail), December 18 (Priority Mail) or December 19 (Priority Mail Express) for delivery in the contiguous US. That leaves about three weeks between the first big sales weekend and the last sensible shipping day. Your mailers need to be on the shelf before that window opens, not halfway through it.

What numbers do you need before you calculate?

Collect these from your own store and shipping data. Everything below works on your figures, not on industry averages.

Input	Where to find it	Example (for illustration only)
Normal orders per day	Store reports, an ordinary month such as September	120
Shipping days per week	Your warehouse schedule	5
Mailers per order	Most orders use 1; split shipments use more	1.1
Peak factor	Last year's Nov–Dec daily orders ÷ ordinary daily orders	2.5
Supplier lead time	Order date to delivery at your door, in weeks	6
Safety stock	Extra weeks of cover you want to hold	2
Stock on hand	Count it, by size	4,000

If you have no history from last year, use your best estimate and keep the safety stock higher. The point is to make the assumption visible so you can check it against reality in the first peak week.

How do you work out peak usage, step by step?

1. Normal weekly usage. Orders per day × shipping days × mailers per order. In the example: 120 × 5 × 1.1 = 660 mailers a week.
2. Peak weekly usage. Normal weekly usage × peak factor. 660 × 2.5 = 1,650 mailers a week.
3. Weeks of peak to cover. Count the weeks from the start of your promotions to your last shipping day. From Black Friday week to December 18 is about four weeks.
4. Peak requirement. 1,650 × 4 = 6,600 mailers for the peak weeks.
5. Add the run-up and the tail. Count the normal weeks between today and the start of peak, plus a week or two after Christmas for returns and gift-card orders, at normal usage.
6. Subtract stock on hand. Whatever is left is what you need to buy, plus safety stock.

Our mailer usage and reorder calculator does steps 1 to 4 for you and shows the reorder point.

What is a reorder point and how do you set it for peak?

The reorder point is the stock level at which you place the next order, so the new stock arrives before you run out:

Reorder point = weekly usage × (lead time in weeks + safety weeks)

With normal usage of 660 a week, a 6-week lead time and 2 safety weeks, the reorder point is 660 × 8 = 5,280 mailers. The catch in peak is that "weekly usage" changes. If you use the normal figure while you are actually shipping 1,650 a week, your reorder point is too low and you will run out before the next delivery arrives.

Two practical rules:

• From October onward, calculate the reorder point with peak usage for any week that falls inside the peak.
• Assume lead times stretch in Q4. Carriers and suppliers are busier, so hold extra safety weeks rather than relying on the quickest lead time you have ever seen.

Which mailer sizes should you stock for peak?

Peak is the wrong moment to add new sizes. Stock the two or three sizes that cover most of your orders, and size them to your best-sellers. Each extra size splits your stock and raises the chance that one size runs out while another sits on the shelf.

Check fit before you commit. A mailer that is too big wastes film and can move you into a higher price tier; one that is too small splits at the seam. Our poly mailer size finder matches mailer size to your folded product, and the size guide lists common US sizes in inches.

Thickness matters too. If you are shipping more heavy items in peak (gift sets, bundles), check that your usual mil still holds them. A burst mailer in December costs a reshipment and a customer.

How do peak surcharges change the packaging decision?

Carriers raise prices during the peak. USPS applied an average 6% increase to Ground Advantage, Priority Mail, Priority Mail Express and Parcel Select from October 4, 2026 to January 17, 2027, according to Supply Chain Dive. UPS and FedEx add residential demand surcharges per package over the same season (see the EasyPost overview in the sources).

You cannot avoid peak pricing, but packaging affects which price you pay. Two checks are worth doing before the rush:

• Weight tiers. Under one pound, USPS Ground Advantage is priced by ounce tier. A heavier mailer than you need can push a parcel into the next tier. Our ounce threshold checker shows how close you are.
• Dimensional weight. Large, light boxes are billed on DIM weight. Soft goods in a snug poly mailer usually stay on actual weight. The DIM weight calculator compares box and mailer side by side.

What if your stock will not last until December?

Run the numbers today. If the gap is small, you may cover it by moving some orders to a second size you already hold. If it is large and your supplier cannot deliver in time, buy only the shortfall from a local distributor for this peak, and keep your main volume with the supplier who gives you the specification and price you want. Then write down what happened: actual peak factor, the week you ran low, how long delivery really took. Those three numbers make next year's plan far more accurate.

Planning next season with a manufacturer

We make poly mailers in our own factory in Istanbul, from extrusion to printing and converting. Orders start from one pallet and you can mix sizes on it, so you can stock the exact sizes you use rather than full pallets of each. Every size and thickness is made to order, including sizes not in our standard range. Ask for a free sample kit and test fit and strength with your own products before next season's order.

Sources

• USPS: 2026 Holiday Shipping Deadlines
• Supply Chain Dive: USPS announces 6% rate increase for 2026 peak season (Aug. 25, 2026)
• EasyPost: Peak season surcharges 2026

General information based on published sources at the time of writing; not legal or tax advice. Carrier and marketplace rules change, check the current version.