Diaper Calculator
Estimate the right diaper size from baby weight and plan how many diapers you may need each month.
This is a practical planning tool for new parents, caregivers, and baby registries.
Result
--
Run the calculation to see the estimate.
| Metric | Value |
|---|---|
| Suggested size | -- |
| Monthly diapers | -- |
| Packs needed | -- |
| Monthly cost | -- |
Quick Answer
The calculator suggests a diaper size from the baby's weight and then estimates monthly diaper count and cost from daily usage.
How to Calculate
- Enter the baby's weight.
- Choose pounds or kilograms.
- Enter diapers per day, pack size, and pack price.
- Click Calculate.
Formula
Monthly diapers = diapers per day x days in month
Packs needed = monthly diapers / diapers per pack
Monthly cost = packs needed x pack price
Worked Examples
Example 1: 8 diapers a day for 30 days is about 240 diapers per month.
Example 2: A 12 lb baby is often in size 2 or size 3 depending on the brand and fit.
Example 3: 240 diapers at 100 per pack and $28 per pack costs about $84 per month.
How to Interpret Your Results
| Output | Meaning | Action |
|---|---|---|
| Suggested size | A common diaper size range based on weight. | Check the brand's size chart before buying. |
| Monthly diapers | Estimated number of diapers used in one month. | Use it to plan purchases. |
| Monthly cost | Estimated spending for the chosen pack size and price. | Compare brands and subscriptions. |
Frequently Asked Questions
Not exactly. Sizes vary by brand, so treat the result as a starting point.
Choose the size that fits best around the legs and waist, especially if there are leaks.
Yes. Multiply the monthly estimate by 12 for a rough annual total.
Related Calculators
References
- OmniCalculator reference page
- Weight-based diaper sizing varies by brand and should be verified on the package.
- Last reviewed: March 2026.