About

Mixed feeding (combination feeding) is a common reality for many parents, yet determining the correct amount of formula "top-up" can be stressful. Overfeeding leads to discomfort, while underfeeding affects weight gain. This tool helps bridge the gap by calculating an infant's Total Daily Energy/Fluid Needs based on their weight and age, then subtracting the estimated breast milk intake to find the required formula volume.

It uses standard pediatric guidelines (typically 150ml per kg of body weight for infants 0-6 months) to provide a safe baseline. This calculator is designed to offer reassurance and a starting point for discussion with your pediatrician or lactation consultant.

Formulas

The calculation calculates the daily deficit:

TotalNeed = Weight_kg × 150ml

The Formula Supplement (FS) is the remainder:

FS = TotalNeed − (BreastFeeds × Est.Vol)

Reference Data

Age	Avg Requirement (ml/kg/day)	Freq (Feeds/Day)
0-3 Months	150 ml/kg	8 - 12
3-6 Months	120 - 150 ml/kg	6 - 8
6-9 Months	100 - 120 ml/kg	5 - 6 (plus solids)
9-12 Months	100 ml/kg	3 - 4 (plus solids)
Conversion	1 oz ≈ 30 ml	Standard Scoop

Frequently Asked Questions

This is the hardest variable. You can use "Weighted Feeds" (weighing baby before and after feeding) or estimate based on pumping sessions. If unsure, assume a conservative average like 60-90ml per full feed for a 3-month-old.

For the first week of life, stomach capacity is tiny (cherry to walnut size). Do not use this calculator for infants under 2 weeks old without medical supervision, as their needs escalate rapidly day-by-day.

Not necessarily. Some parents choose to replace one entire feed with formula, while others top up small amounts after every breastfeed. The "Per Feed" result below assumes an even distribution.

Once solids are introduced (approx. 6 months), milk requirements decrease gradually. Use the Age dropdown to adjust the ml/kg calculation factor accordingly.