How Much Formula for a 3-Week-Old?
At three weeks, most babies are back above birth weight and feeding is settling into a rhythm, until a growth spurt shows up and the bottles empty faster than you expected. If you are searching how much ml of formula milk to be given to a 3 weeks old baby, the short answer is about 495–675 ml (17–23 oz) per day, or roughly 60–95 ml (2–3.2 oz) per feed. This guide shows how that number is calculated from your baby's weight using the 150 ml/kg/day starting point, with a ml and oz lookup table and a worked example.
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How this guide is maintained
Written by the Baby Milk Calculator editorial team and reviewed against primary public-health guidance. This page is for general education, not individualized diagnosis or treatment.
Last content update
October 15, 2026
Primary sources
6 official references
Written by
Baby Milk Calculator editorial team
Reviewed against
Guidance from AAP and CDC
Good for
General reference and planning
Sources inform this guide. Citing an organization does not mean it authored, reviewed, or endorsed this page. See our editorial policy for how we use references and handle corrections.
How Much Formula for a 3-Week-Old Baby Per Day?
The American Academy of Pediatrics (AAP) and the CDC describe a typical intake of about 150 ml of milk per kilogram of body weight per day in the early weeks. A 3-week-old usually weighs between 3.3 and 4.5 kg (7.3–9.9 lbs), so the daily target is about 495–675 ml (17–23 oz).
This is a starting estimate, not a quota. Babies vary day to day, and a healthy baby who takes a bit more or less while gaining weight steadily is usually doing fine. Wet diapers, alertness and growth at check-ups tell you more than any single bottle.
3 Week Old Formula Amount in ml: Worked Example
Worked example
A 3-week-old weighing 3.9 kg at 150 ml/kg/day: 3.9 × 150 = 585 ml daily. Across 8 feeds: 585 ÷ 8 ≈ 73 ml (2.5 oz) per feed. Across 7 feeds: 585 ÷ 7 ≈ 84 ml (2.8 oz) per feed.
To calculate your own baby's amount, multiply their weight in kilograms by 150, then divide by the number of feeds they usually take in 24 hours. The formula calculator does this instantly in ml or oz.
3-Week-Old Formula Amount Lookup Table (ml and oz)
Find your baby's approximate weight, then use the column that matches how many feeds they take each day.
| Weight | Daily total | Per feed ×8 | Per feed ×7 |
|---|---|---|---|
| 3.3 kg / 7.3 lbs | 495 ml · ~16.7 oz | 62 ml · ~2.1 oz | 71 ml · ~2.4 oz |
| 3.6 kg / 7.9 lbs | 540 ml · ~18.3 oz | 68 ml · ~2.3 oz | 77 ml · ~2.6 oz |
| 3.9 kg / 8.6 lbs | 585 ml · ~19.8 oz | 73 ml · ~2.5 oz | 84 ml · ~2.8 oz |
| 4.2 kg / 9.3 lbs | 630 ml · ~21.3 oz | 79 ml · ~2.7 oz | 90 ml · ~3.0 oz |
| 4.5 kg / 9.9 lbs | 675 ml · ~22.8 oz | 84 ml · ~2.8 oz | 96 ml · ~3.2 oz |
Between two rows? Multiply the exact weight by 150 and divide by your feed count. You can also use the Baby Milk Calculator.
How Often Should a 3-Week-Old Eat?
Most formula-fed 3-week-olds feed 7–8 times in 24 hours, about every 3 to 4 hours. Breastfed babies often feed 8 or more times. In the early weeks, most babies should not be left to go much beyond about 4 hours between daytime feeds unless your pediatrician has advised otherwise.
Responsive feeding means watching for early hunger cues (rooting, hands to mouth, turning the head) instead of the clock. Crying is a late cue and makes feeding harder to start. Slowing their suck, relaxing their hands or turning away are signs they are full.
3 Week Old Growth Spurt: What If My Baby Is Still Hungry?
A growth spurt is common at around 2–3 weeks. Your baby may drain bottles quickly, ask to feed again soon after, and be fussier than usual. Spurts usually last a few days.
- Feed a little earlier when you see early hunger cues.
- Offering an extra 10–15 ml in the bottle is reasonable if your baby is clearly still asking for more.
- Use paced bottle feeding so your baby can signal fullness.
- Return to the calculated range once things settle; the daily total is a baseline, not a ceiling.
If your baby seems constantly hungry for more than several days, or is gaining weight too slowly or too quickly, talk with your pediatrician.
Is My 3-Week-Old Getting Enough Formula?
- Wet diapers:at least 5–6 a day.
- Weight gain: steady gain along their growth curve at check-ups.
- Settling: relaxed and content for a while after most feeds.
- Alertness: awake and responsive between feeds.
Contact your pediatrician if diapers drop off, your baby is hard to wake for feeds, vomits repeatedly, or weight gain stalls. This guide is general information, not individual medical advice.
The Bottom Line
A 3-week-old typically takes about 495–675 ml (17–23 oz) of formula per day, or roughly 60–95 ml (2–3.2 oz) per feed across 7–8 feeds. Use the table as a starting point and let hunger and fullness cues, diapers and growth guide the fine-tuning. For older babies see the 1-month-old guide.
Primary sources
Official references for this page
These links are the main public-health and pediatric references used to maintain this guide.
01
How Often and How Much Should Your Baby Eat?HealthyChildren.org / American Academy of Pediatrics
AAP overview of breast milk and formula feeding frequency and volumes.
02
Amount and Schedule of Baby Formula FeedingsHealthyChildren.org / American Academy of Pediatrics
AAP guidance on formula intake by weight and feeding cadence.
03
How Much and How Often to Feed Infant FormulaCDC
CDC guidance on first days, first months, and 6-12 month formula feeding.
04
How Much and How Often to BreastfeedCDC
CDC expectations for frequent newborn breastfeeding and normal changes over the first weeks and months.
05
Is Your Baby Hungry or Full? Responsive Feeding ExplainedHealthyChildren.org / American Academy of Pediatrics
AAP explanation of infant hunger and fullness cues.
06
How to Tell if Your Breastfed Baby is Getting Enough MilkHealthyChildren.org / American Academy of Pediatrics
AAP signs of adequate intake, including diapers, weight gain, and satiety.
Frequently Asked Questions
How much ml of formula milk to be given to 3 weeks old baby?
Most 3-week-olds weigh roughly 3.3–4.5 kg (7.3–9.9 lbs). Using the 150 ml/kg/day starting point from the AAP and CDC, that is about 495–675 ml (17–23 oz) per day. Divided across 7–8 feeds, most 3-week-olds take about 60–95 ml (2–3.2 oz) per feed. Treat it as a starting estimate and follow your baby's cues.
How much formula for 3 week old babies per feed?
A common per-feed range is 60–95 ml (2–3.2 oz), offered every 3–4 hours or whenever early hunger cues appear. A worked example: a 3.9 kg baby needs 3.9 × 150 = 585 ml per day, which is about 73 ml (2.5 oz) per feed across 8 feeds or 84 ml (2.8 oz) across 7 feeds.
What is a 3 week old formula amount in ml if my baby is still hungry?
Around 2–3 weeks many babies have a growth spurt and want to feed more often. Offering a little extra (for example 10–15 ml more per bottle) or feeding sooner is reasonable when your baby shows clear hunger cues. Stop when they show fullness cues such as slowing their suck or turning away; do not push them to finish the bottle.
How often should a 3-week-old formula-fed baby eat?
Most formula-fed 3-week-olds feed 7–8 times in 24 hours, roughly every 3–4 hours. Breastfed babies usually feed 8 or more times. Newborns generally should not go much longer than about 4 hours between feeds during the day unless your pediatrician has said otherwise.
How do I know a 3-week-old is getting enough formula?
Reliable signs are at least 5–6 wet diapers a day, steady weight gain at check-ups, regular soft stools, and a baby who is alert between feeds and settles after eating. If diaper counts drop, your baby is hard to wake for feeds, or weight gain stalls, contact your pediatrician.
Can I use the same amounts for expressed breast milk at 3 weeks?
Yes. The 150 ml/kg/day starting point is used for both formula and expressed breast milk at this age. Babies fed directly at the breast are judged by feed count, diapers and weight gain rather than measured volume.
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