Costco Diaper Sale 2025: How To Save in November

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Parents with a Costco membership, get ready to save this fall, because the semi-annual Kirkland diaper sale should return in November. The last Kirkland diaper sale happened July 14 - 27, with savings of $4 - $10 per box (25% - 27% off), depending on the size. These savings can add up fast if you're buying multiple boxes (the limit is three), and the discount applies automatically at checkout. And just like the deals in the Costco Coupon Book, no coupons are actually required.

We've tracked Costco deals and diaper sales for years, and we've noticed Costco typically follows a pretty consistent pattern. Here's what to expect this fall when The Krazy Coupon Lady predicts the sale will return.

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The Costco Diaper Sale is a twice-a-year, multi-day event that knocks up to $10 off each box of Kirkland diapers automatically at checkout.

Costco has historically run this sale twice yearly, typically once in June and again in November. But in 2025, they didn't start the summer sale until July 14, and it lasted until July 27. The discount applies to all sizes of Kirkland Signature diapers, regularly priced at $39.99 for sizes 3 and up, $19.99 for size 2, and $14.99 for size 1. Savings happen instantly at checkout, no coupons required.

Note that Kirkland recently switched from Kimberly-Clark to First Quality (the maker of Cuties diapers) and has changed box sizes and prices, so the discount structure is slightly different this year.

KCL predicts the next Costco Diaper Sale will happen Nov. 10 - 16, 2025.

Costco Diaper Sale predicted start date of November 10, 2025

Costco never announces this sale in advance, but the team at The Krazy Coupon Lady predicts we'll see another Costco Diaper Sale take place Monday, Nov. 10 - Sunday, Nov. 16. The most recent sale happened July 14 - 27, for all sizes of Kirkland diapers.

After the November event, the next Costco diaper sale likely won't happen until July 13 - 26, 2026, so it could be worth stocking up. Keep in mind that the limit is typically three boxes during the sale.

How do we make our prediction?

Our team at The Krazy Coupon Lady has tracked the Costco diaper sale pattern for years. Here are the most recent sale dates:

July 14 - 27, 2025
No sale in November 2024, likely due to the manufacturer switch
June 3 - 16, 2024
Nov. 13 - 19, 2023
June 5 - 28, 2023
Sept. 28 - Oct. 23, 2022
March 25 - April 3, 2022

You can claim the same diaper sale prices online or in-store.

Unlike many of the items you can buy from Costco online, there's no online markup on diapers, meaning that the price you see for diapers on Costco.com is the same low price you'll pay in the warehouse. Plus, shipping is free on Costco diapers.

A Costco membership isn't required to grab this deal online, but nonmembers will pay a 5% fee at checkout.

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There's a limit of three boxes per member.

Costco typically limited diaper sale purchases to two boxes per size, per membership, per day. But in the fine print for the July 2025 sale, there was a limit of three boxes per member.

KCL TIP: Need more boxes than the limit? Ask friends with a Costco membership to help you stock up.

Buy enough to last awhile, as the sale only happens twice a year.

Since this sale only comes around once every six months, it's a good chance to stock up if you like the Kirkland brand diapers. Just calculate your monthly diaper usage and multiply that by six, but keep the limit of three in mind.

Here are the current diaper counts per box:

Size 1: 96 diapers per box
Size 2: 112 diapers per box
Size 3: 222 diapers per box
Size 4: 198 diapers per box
Size 5: 168 diapers per box
Size 6: 132 diapers per box

Ask for a price adjustment if you bought full-price Kirkland diapers within 30 days of the sale.

Recently bought Costco diapers at full price? The Costco price adjustment policy gives you money back if an item goes on sale within 30 days of purchase.

For in-store purchases, just visit the Returns desk with your membership card (no receipt needed) to get a refund for the price difference. For online orders, fill out Costco's price adjustment form on their website.