Baby Weight Gain Calculator

Track your baby’s weight progress clearly and confidently.

Enter birth weight, current weight, and days since birth to calculate:

  • Total weight change (grams)
  • Average daily gain
  • Percentage change from birth weight

This tool is for informational tracking only and does not replace medical advice.

Calculate Baby Weight Gain

Newborn Weight Gain Reference (0–3 Months)

Stage What’s Normal
Day 1–5 Up to 7–10% weight loss
Day 10–14 Regains birth weight
0–3 Months 20–30 g per day average gain
Weekly Average 150–200 g per week

These are general reference ranges. Individual babies may vary.

Understanding Newborn Weight Changes

In the first few days, most newborns lose 7–10% of their birth weight. This is normal due to fluid loss.

By day 10–14, babies typically regain their birth weight.

After that, average weight gain in the first 3 months is:

  • Around 20–30 grams per day
  • Roughly 150–200 grams per week

Every baby grows at a slightly different pace. Consistent gain matters more than comparison.


When to Speak to a Doctor

  • Baby has not regained birth weight by 2 weeks
  • Daily gain consistently below 15–20 g after day 10
  • Baby seems lethargic or feeds poorly
  • Fewer wet diapers

What Actually Affects Weight Gain

  • Effective latch
  • Feeding frequency
  • Milk transfer (not just time at breast)
  • Illness
  • Prematurity