How Much Weight Do Babies Gain per Week? | Weekly Gains

Babies typically gain about 5–7 ounces (140–200 grams) per week during the first few months, with the rate slowing as they approach 6 months of age.

You probably expected a straight number when you Googled this. But the infant scale doesn’t work like a kitchen scale — it follows a wide, normal range that shifts month by month.

Healthy newborns generally fall into a pattern of about 5 to 7 ounces per week for the first several months, though individual babies can vary. What matters most isn’t a single week’s number but whether your baby is growing consistently along their own curve.

What’s Considered Normal Weekly Weight Gain

From about day five through month four, the typical baby packs on roughly 5–7 ounces (170 grams) per week. That’s the window cited by most pediatric sources, including the Mayo Clinic and Texas Children’s Hospital.

After four months, the pace eases. Between 4 and 6 months, average gain drops to about 4–5 ounces per week. By 6 to 12 months, it slows further to roughly 2–3 ounces per week — about a pound per month.

Many babies double their birth weight by 3–4 months, and triple it by their first birthday. These are average benchmarks, not strict rules.

Why Expectations About Weight Gain Vary

You may have heard two different numbers from two different sources. That’s partly because feeding method shifts the timeline.

• Breastfed vs formula-fed: In the first three months, breastfed babies often gain a bit faster. Between 3 and 4 months onward, formula-fed babies tend to catch up and may gain more quickly.
• Birth weight matters: A baby born at 5½ pounds will gain differently than one born at 8¾ pounds. The starting point changes the range.
• Individual growth spurts: Babies don’t gain steadily every week. They often have “spurts” where weight jumps, followed by slower weeks.
• Gestational age: Preterm babies may follow a separate growth chart adjusted for their due date, not their birth date.

The percentile your baby settles into — 10th, 50th, 90th — matters less than whether they stay on that curve. A drop across multiple percentiles is worth a conversation with your pediatrician.

Tracking Your Baby’s Growth Curve

Pediatricians use the WHO growth charts for the first two years. Your baby’s weight, length, and head circumference are plotted at well-child visits, usually at 1, 2, 4, 6, 9, and 12 months.

At home, weekly weigh-ins can be helpful if your baby is gaining slowly or if you’re concerned about milk supply. Use the same scale at the same time of day, ideally with a naked baby, for consistency.

If your baby doesn’t gain at least a half-ounce (15 grams) per day by the fourth or fifth day after birth, it may be flagged as a slow weight gain concern according to Children’s Hospital of Philadelphia. This threshold helps identify issues early, often before they become serious.

These numbers are averages from large populations. Your baby might consistently gain at the low end or the high end and still be perfectly healthy — what matters is the pattern over weeks, not a single week’s number.

When Should You Talk to Your Pediatrician?

Most babies follow a predictable trajectory, but a few warning signs warrant a call. Trust your gut — if something feels off, it’s always reasonable to ask.

1. Not back to birth weight by day 10–14: Most newborns regain their birth weight within two weeks. If not, your pediatrician may want to check feeding and hydration.
2. Consistently less than the minimum: Gaining less than a half-ounce per day after day four can signal slow weight gain, especially if paired with fewer wet diapers.
3. Weight loss after the first month: Initial weight loss is expected (up to 7% of birth weight in the first few days). Losing weight after the first month is unusual.
4. Dropping percentiles sharply: A baby who falls from the 40th to the 5th percentile over a few months needs evaluation, even if total gain seems okay.
5. Poor feeding cues or sleepiness: A baby who rarely wakes to feed or doesn’t seem hungry may not be taking in enough calories.

One low week on the scale usually isn’t a crisis. Slow weight gain is typically identified over two or more visits, not a single weigh-in.

What Affects a Baby’s Weekly Gain

Several factors can tweak the weekly number. Feeding method is the most common, but health and temperament play a role too.

Breastfed babies depend on milk supply and latch efficiency. Formula-fed babies get a consistent calorie count per ounce, which can lead to steadier (but not necessarily better) gain. Illness, reflux, or a tongue-tie can also temporarily slow growth.

According to Healthline’s infant weight guide, the typical range of 5–7 ounces per week applies broadly, but babies who are very active or who sleep through the night early may gain a bit less some weeks. The key is the overall trajectory, not the weekly variability.

The Bottom Line

Healthy babies typically gain 5–7 ounces per week for the first four months, then slow to 4–5 ounces from 4 to 6 months, and 2–3 ounces through the rest of the first year. The exact number matters less than consistent growth along your baby’s own curve.

If your baby’s weight gain seems off, your pediatrician can review the full picture — including feeding logs, diaper output, and their individual growth chart — to determine whether any adjustments are needed.