Unit-price math, done for you at 2 a.m.
If you are reading this one-handed, with a baby asleep on your chest and a cart full of diapers you are not sure you can afford — this site was built for exactly that moment. Stores show you the big price on the box. We show you the small price that matters: what one diaper, one ounce of formula, one wipe actually costs. A 6-cent difference sounds like nothing. Over 2,800 diapers in the first year, it is about $168 — a month of groceries, found in one decision.
| Item | Unit math | Month |
|---|---|---|
| Diapers ×240 (8/day) | $0.24 each | $57.60 |
| Formula ×~700 oz | $0.19 / oz | $133.00 |
| Wipes ×~560 | $0.03 each | $16.80 |
| Diaper cream, bags, misc. | — | $12.00 |
| TOTAL (MODEL) | $219.40 |
Same baby, store-brand diapers at $0.17 and generic formula at $0.14/oz:
about $168/month — roughly $51 back in your pocket, every month.
Run your own numbers ↓ it takes 20 seconds.
Cost-per-diaper calculator Monthly cost simulator
Store-brand diaper, big box, model example. The number every other brand has to beat.
Small "convenience" packs at the corner store. Same diaper, nearly double the unit price.
Roughly 2,500–3,000 changes in year one. Small unit gaps become real money at this volume.
1. Cost-per-diaper calculator — Paste any pack price and count. Get cost per diaper, per day, per month, and what switching would save in a year. Twins toggle included.
2. Monthly baby cost simulator — Age, feeding type, diapers per day. Out comes a monthly and first-year total you can actually plan around.
3. Diaper cost database — Brands × sizes Newborn to 6, with typical pack examples and the exact formula behind every number.
4. Money you're owed — WIC, SNAP, registry completion discounts, hospital freebies — and for expat moms in Japan, the birth allowance and child allowance. Money many families never claim.
5. Buying rules that stop the leaks — The stockpile trap, the "% off" illusion, and the registry items that quietly eat $300.
Every formula on this site is shown in plain sight. If our math is ever wrong, the workings are right there for you to catch it.
Japanese diapers (Merries, Moony, Genki!, Whito) are sized in kilograms, sold in smaller packs, and genuinely excellent — but the unit math works differently, and so do the benefits. Our guide for expat moms in Japan covers yen-per-diaper math, size conversion, where the big packs hide, and the ¥420,000-ish birth allowance (general guide figure — always check the official source) that too many foreign moms file late.
PR — SHOPPING SEARCH LINKS (NO AFFILIATE ID YET — SEE DISCLOSURE)
Search links open retailer search results. Compare the unit price — not the box price — before you buy.