How this calculator works
Diaper use is highest in the first weeks and falls steadily as a baby grows. A newborn wets and soils often because the bladder is tiny, so expect eight to twelve changes a day; by six months the count is nearer six or seven, and an older toddler uses four or five. The calculator uses the middle of each commonly quoted range and multiplies it by the number of days in your period. Boxes are then rounded up, because you cannot buy a fraction of a box, and the cost is the number of boxes multiplied by the price per box. The period in months uses the engine month of 30.44 days.
Formula
diapers needed = diapers per day x period in days. Boxes = ceiling(diapers needed / diapers per box). Cost = boxes x cost per box.
Worked example
A baby aged 5 to 8 months uses about 7 diapers a day, so a 30 day period needs 210 diapers. A box of 100 means buying 3 boxes, which at $35 each costs $105.
Advertisement
Frequently asked questions
How do I know which age group to pick?
Choose the band that contains the baby current age, not the due date band. The rates overlap slightly by design, so use the group where the baby sits today.
Should I buy in bulk?
Only up to the size the baby will still fit. Babies move up a size every couple of months in the first year, so a very large bulk purchase can outlast the fit and needs to be balanced against the per diaper saving.
Why does the calculator round boxes up?
Shops sell whole boxes. Rounding up avoids running short, and the extra box usually carries into the next period rather than being wasted.
Does this include wipes?
No. Wipes, creams and nappy sacks are separate lines, so add them to your own budget. The diaper count is the largest recurring item and the one that varies most by age.