Calculate Baby Weight Pregnancy

This calculator estimates your baby's weight based on your pregnancy stage. Understanding your baby's growth helps monitor a healthy pregnancy.

How to Use This Calculator

To estimate your baby's weight:

Enter your current pregnancy week (1-40)
Select your baby's sex (optional)
Click "Calculate" to see the estimated weight

The calculator provides an average estimate. Actual baby weight can vary based on individual factors.

How Baby Weight is Calculated

Baby weight during pregnancy follows predictable growth patterns based on gestational age. The calculator uses average growth curves from medical research.

Weight (grams) = Base Weight + (Growth Rate × Pregnancy Week) Base Weight = 300 grams (average at conception) Growth Rate = 15 grams per week (average)

This formula provides a general estimate. Actual growth may vary by ±20% depending on individual factors.

Factors Affecting Baby Weight

Several factors influence baby weight during pregnancy:

Genetics (family history of birth weight)
Nutrition (adequate prenatal vitamins)
Activity level (exercise during pregnancy)
Medical conditions (gestational diabetes)
Multiple pregnancies (twins, triplets)

While the calculator provides estimates, always consult with your healthcare provider for personalized advice.

Normal Weight Range for Babies

At full term (37-40 weeks), babies typically weigh between:

Baby Sex	Average Weight	Range
Male	3.2 kg (7.0 lbs)	2.5-4.1 kg
Female	3.0 kg (6.6 lbs)	2.3-3.8 kg

Premature babies may weigh less, while babies born after 40 weeks may be heavier.

Baby Weight by Pregnancy Trimesters

Baby growth accelerates during each trimester:

Trimester	Weeks	Average Weight Gain	Baby's Size
First	1-12	0.4-0.8 kg	Fist to palm size
Second	13-27	1.1-1.8 kg	Football to head size
Third	28-40	1.4-2.3 kg	Full-term baby

Example

At 20 weeks, a baby typically weighs about 350 grams (12.3 oz). By 30 weeks, the average weight increases to 1.2 kg (2.6 lbs).

Frequently Asked Questions

Is the calculator accurate for all pregnancies?: The calculator provides average estimates. Individual pregnancies may vary by up to 20%. Always consult your healthcare provider for personalized advice.
When should I be concerned about baby weight?: Consult your doctor if your baby's growth is significantly below or above the expected range, or if you notice other concerning symptoms.
Can exercise affect baby weight?: Moderate exercise is generally safe during pregnancy. Vigorous exercise may lead to slightly higher birth weights, but this is usually within normal ranges.
How does nutrition impact baby weight?: Proper nutrition supports healthy growth. Prenatal vitamins and a balanced diet help ensure your baby reaches a healthy weight.
What's the difference between birth weight and pregnancy weight?: Pregnancy weight refers to your baby's growth during gestation. Birth weight is the actual weight at delivery, which may differ slightly from pregnancy estimates.