How the diaper estimate works
Daily diaper use is highest in the early months, then usually falls as feeding patterns settle, babies start solids, and toilet-training gets closer. This calculator uses age-based planning bands for a typical disposable-diaper routine and lets you override the daily count if your baby is usually above or below that range.
Size guidance works differently. Diaper brands generally size by weight, not age, which is why the calculator asks for both. Age helps estimate how many changes you may go through, while weight gives a better starting point for the current diaper size and the next likely size step.