Growth Velocity Calculator

Q: What is a normal growth velocity for a baby?

Normal weight gain for infants is roughly 25–35 g/day in the first 3 months, slowing to 15–20 g/day by 3–6 months and 10–13 g/day from 6–12 months. For length, babies typically grow about 25 cm in the first year.

Q: My baby gained no weight this week — should I worry?

Short-term fluctuations are normal. A single week of flat or minimal weight gain isn't concerning if the overall trend is normal. If weight gain is flat for 2+ weeks in an infant under 6 months, contact your pediatrician.

Enter two measurements taken at different ages to calculate your child's rate of weight gain and height/length gain over time.

By Dysin, software engineer & parent · About & methodology

Last updated: May 2026

What is growth velocity? Growth velocity is the rate at which a child gains weight or height over a specific time period. Pediatricians use it to detect growth faltering or acceleration earlier than single-point percentile readings — a child can be at the 40th percentile but gaining too slowly or too quickly. WHO provides velocity reference standards for weight, length, and head circumference from birth to 24 months.

📈 Rate of Growth ⚡ Instant Results 🔒 No Sign-up Required 📱 Works on Any Device

Enter Two Measurements

Provide your child's measurements at two different points in time. Both weight and height/length are optional — enter whichever you have.

Sex

Boy Girl

Measurement 1 (Earlier)

Date

Or Age (months)

Weight

Height / Length

Measurement 2 (Later)

Date

Or Age (months)

Weight

Height / Length

This tool is for informational purposes only and is not a substitute for professional medical advice. Growth velocity should be interpreted alongside percentile tracking and clinical assessment. Always consult your child's pediatrician.

Understanding Growth Velocity

Growth velocity measures how fast a child is growing over a defined time interval, expressed as grams per day (weight) or centimeters per month (height). While a single percentile reading tells you where your child falls relative to peers at one moment, velocity tells you whether they're maintaining, gaining, or losing ground on the growth curve.

Why Velocity Matters

A child at the 15th percentile who is growing at a normal velocity is healthy — they're simply smaller than average. But a child at the 50th percentile whose velocity has dropped below normal may be heading toward growth faltering, even though their current percentile looks fine. Velocity detects problems earlier than single-point percentile readings.

Typical Weight Gain Rates

0–3 months: 25–35 g/day (175–245 g/week)
3–6 months: 15–20 g/day (105–140 g/week)
6–12 months: 10–13 g/day (70–90 g/week)
1–2 years: 6–8 g/day (~2 kg/year)
2–5 years: 5–6 g/day (~2 kg/year)

Typical Height Gain Rates

0–12 months: ~25 cm/year (2+ cm/month)
1–2 years: ~12 cm/year (1 cm/month)
2–5 years: ~7–8 cm/year
5–puberty: ~5–6 cm/year
Puberty: 8–12 cm/year (growth spurt)

When to Be Concerned

Discuss with your pediatrician if your child's weight gain drops below the expected range for their age for more than 2–4 weeks (in infants) or if height velocity is below 4 cm/year after age 4 (excluding the normal deceleration before puberty). Short-term fluctuations during illness or growth spurts are normal.

Tips for Accurate Velocity Measurement

Use measurements taken at least 2–4 weeks apart for weight and 3–6 months apart for height
Measure at the same time of day using consistent technique
Use the same scale/equipment for both measurements when possible
Short intervals amplify measurement error — longer intervals give more reliable velocity

Next Steps

Track all your child’s measurements in one place with the Growth Tracker, or check if your baby is approaching a growth spurt window. For single-point assessments, use the weight-for-age or height-for-age calculators.

Growth Velocity FAQ

What is a normal growth velocity for a baby?

Normal weight gain for infants is roughly 25–35 g/day (6–7 oz/week) in the first 3 months, slowing to 15–20 g/day by 3–6 months and 10–13 g/day from 6–12 months. For length, babies typically grow about 25 cm in the first year (roughly 2 cm/month), then 12 cm in the second year.

How often should I measure growth velocity?

For weight, measurements 2–4 weeks apart can be meaningful in infants. For height/length, measurements should be at least 3 months apart because height changes are small and measurement error is relatively large. Most pediatricians assess velocity at each well-child visit (every 2–3 months in infancy, every 6–12 months later).

Is growth velocity more important than percentile?

They're complementary. Percentile tells you where your child is; velocity tells you how fast they're moving. A normal velocity at any percentile means healthy growth. Both should be tracked together — use our Growth Tracker for percentile trends over time, and this calculator for velocity between specific visits.

My baby gained no weight this week — should I worry?

Short-term fluctuations are normal due to feeding patterns, hydration, and bowel timing. A single week of flat or minimal weight gain isn't concerning if the overall trend is normal. If weight gain is flat for 2+ weeks in an infant under 6 months, or you notice other signs (reduced feeding, fewer wet diapers), contact your pediatrician.

What's the minimum time interval for accurate velocity?

For weight: at least 1–2 weeks in infants, 4 weeks in older children. For height: at least 3 months (ideally 6 months). Shorter intervals amplify measurement error and can produce misleading results. This calculator will warn you if the interval is too short for a reliable estimate.