the price-per-unit x-ray machine

Cost Per Diaper Calculator

You'll buy roughly 6,000 of these before potty training. The per-diaper price is the number that matters — here's the ten-second way to get it.

Enter the price and count for two boxes and get the true cost per diaper, side by side. The count is printed right on the box — this just does the division your sleep-deprived brain shouldn't have to.

Prices move constantly, especially with subscribe-and-save toggles. YMMV.

Box A

Box B

Pre-filled with a real-world shape: the big box wins here — but only by 3¢ a diaper, and a sale on the smaller box flips it. That's why you check every time.

Skip the typing — check live prices

PriceXray searches Amazon and sorts by cost per count automatically, coupons included — add Walmart, eBay and Google Shopping to the same search with one tap.

Compare diaper prices per count → Compare baby wipes per count →

Three things worth knowing about diaper math

1. Bigger box ≠ always cheaper. It's the way to bet, but sales and subscription pricing regularly make the mid-size box the actual winner. The math takes ten seconds; the assumption costs real money over 6,000 diapers.

2. Cost per diaper rises with size. The same brand can run ~20¢ at size 1 and 40¢+ at size 6, because bigger diapers mean fewer per box. When your kid sizes up, re-run the comparison — the cheapest brand at size 2 isn't automatically the cheapest at size 5.

3. Don't overbuy a size. The one genuine caution against bulk: babies outgrow sizes on their own schedule. A stack of size-3 boxes your kid graduated past is the most expensive kind of savings.

What diapers cost right now

We track diaper and wipes prices monthly across retailers — current leaderboard, best value, and whether the big box is actually winning this month:

FAQ

How do I calculate cost per diaper?
Box price ÷ diaper count. $54.99 for 198 diapers ≈ 27.8¢ each. The count is on the front of the box.
Is the biggest box always cheapest?
Usually, not reliably. Sales and subscribe-and-save flips happen all the time — check the per-count number, not the box size.
Why does the per-diaper cost go up with size?
Bigger diapers, fewer per box, similar box price. Budget per diaper and the real cost stays visible as your kid grows.

More tools

Our Amazon links are plain links — no affiliate tag, no commission.

Amazon doesn't allow affiliate sites to run price alerts, so we chose the alerts. If eBay or Walmart links ever earn us a commission, they'll be labeled (paid link) — and it never changes the price you pay. The whole thing runs on Ko-fi tips.

This calculator runs entirely in your browser — nothing you type is sent anywhere.

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