Exclusive pumpers usually pump 8–12 times a day in the first weeks to build supply, then can often reduce to 5–7 sessions once supply is established (around 12 weeks). Pumping at night helps maintain supply because prolactin levels are higher.
How to use the Exclusive Pumping Calculator
- Baby’s age
- Daily milk target
- Pumping sessions per day
- First session
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter your baby’s age, your daily target, number of sessions and when you start.
Inputs explained
| Field | What to enter |
|---|---|
| Baby’s age | Units: months, years, weeks |
| Daily milk target | Units: mL, fl oz |
| Pumping sessions per day | A number |
| First session | A clock time (hours and minutes) |
What each result means
- Milk per session = [Daily milk target]÷[Pumping sessions per day]
- Interval between sessions = 24÷[Pumping sessions per day]
- Second session = mod([First session] + 24÷[Pumping sessions per day], 24)
- Third session = mod([First session] + 2×24÷[Pumping sessions per day], 24)
- Fourth session = mod([First session] + 3×24÷[Pumping sessions per day], 24)
Example values
How the main result changes when Baby’s age changes and everything else stays at the example values above:
| Baby’s age (months) | Milk per session (mL) |
|---|---|
| 1 | 100 |
| 1.5 | 100 |
| 2 | 100 |
| 2.5 | 100 |
| 3 | 100 |
| 4 | 100 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Daily target ≈ 750–1,035 mL (25–35 oz) from 1 month
Per session = daily target ÷ sessions
Interval = 24 h ÷ sessions
Worked example
Inputs — Baby's age: 2 months; Daily milk target: 800 mL; Pumping sessions per day: 8; First session: 06:00.
Results — Milk per session = 100 mL; Interval between sessions = 3 h 0 min; Second session = 9:00 AM; Third session = 12:00 PM; Fourth session = 3:00 PM; Suggested sessions for this age = 8–12 a day while building supply.
Key terms
- Exclusive pumping
- Feeding a baby only expressed breast milk.
Frequently asked questions
How often should I pump?
8–12 times a day in the early weeks, including at least once at night.
How long should each session be?
About 15–20 minutes, or until 2–5 minutes after milk stops flowing.
When can I drop sessions?
Usually after about 12 weeks once supply is stable, one session at a time.