1-Month-Old Baby Weight & Length Chart
By one month, most babies have regained their birth weight and then some. Expect roughly 1–2 lbs of gain and about an inch of length since birth.
Boy — 50th %ile
Girl — 50th %ile
⚖️ Weight by Percentile
| Percentile | 👦 Boy | 👧 Girl |
|---|---|---|
| 5th Percentile | 8 lbs 6 oz | 7 lbs 11 oz |
| 10th Percentile | 8 lbs 10 oz | 8 lbs 3 oz |
| 25th Percentile | 9 lbs 4 oz | 8 lbs 10 oz |
| 50th Percentile (median) | 9 lbs 15 oz | 9 lbs 4 oz |
| 75th Percentile | 10 lbs 9 oz | 9 lbs 15 oz |
| 90th Percentile | 11 lbs 4 oz | 10 lbs 6 oz |
| 95th Percentile | 11 lbs 11 oz | 10 lbs 13 oz |
📏 Length/Height by Percentile
| Percentile | 👦 Boy | 👧 Girl |
|---|---|---|
| 5th Percentile | 1' 8.8" | 1' 8.4" |
| 10th Percentile | 1' 9" | 1' 8.6" |
| 25th Percentile | 1' 9.3" | 1' 8.9" |
| 50th Percentile (median) | 1' 9.5" | 1' 9.1" |
| 75th Percentile | 1' 9.8" | 1' 9.4" |
| 90th Percentile | 1' 10.1" | 1' 9.7" |
| 95th Percentile | 1' 10.3" | 1' 9.9" |
📊 What Does My Baby's Percentile Mean?
A baby at the 50th percentile weighs more than 50% of babies the same age. The 25th–75th percentile range is considered average. Any percentile from the 5th to the 95th is medically normal — your baby's growth curve matters more than their rank. A consistently healthy 10th-percentile baby is thriving; a baby who drops from the 70th to the 30th percentile warrants a conversation with your pediatrician.
🌟 Developmental Milestones
- Lifts head 45° during tummy time
- Follows objects side-to-side with eyes
- Coos and makes small sounds
- May start social smiling
Your baby is becoming more alert. Tummy time (3–5 minutes, several times daily) strengthens neck muscles critical for later milestones.
🍼 Feeding at 1 Month Old
Breastfed babies feed 8–12 times per day (every 2–3 hours). Formula-fed babies take 2–4 oz every 3–4 hours.
🚨 Talk to Your Pediatrician If…
- Not back to birth weight
- Fewer than 6 wet diapers daily
- Difficulty latching or excessive crying after feeds
- Not making eye contact
Frequently Asked Questions
How much should a 1-month-old weigh?
The WHO median weight is 4.5 kg (9.9 lbs) for boys and 4.2 kg (9.3 lbs) for girls at 1 month. A healthy range runs from about 3.8–5.3 kg (8.4–11.7 lbs).
How long should a 1-month-old be?
Median length is about 54.7 cm (21.5 in) for boys and 53.7 cm (21.1 in) for girls.
How much weight should a 1-month-old gain per week?
Most babies gain 5–7 oz (140–200 g) per week during the first few months. Your pediatrician will track this at the 1-month well visit.
Is my 1-month-old growing too fast?
Rapid growth (growth spurts) around 2–3 weeks and 6 weeks is normal. Babies may seem hungrier than usual for a few days.