Baby Weight: lbs to kg Conversion for New Parents

June 8, 2025 • 4 min read

When your baby is born, one of the first things you will hear is their weight. Depending on where you live, it might be announced in pounds and ounces or in kilograms. Here is a clear guide to help new parents understand baby weights in both systems.

The Conversion Formula

Newborn Weight Reference Chart

Here are common newborn weights converted between systems:

• ▶ 5 lbs 8 oz = 2.49 kg
• ▶ 6 lbs 0 oz = 2.72 kg
• ▶ 6 lbs 8 oz = 2.95 kg
• ▶ 7 lbs 0 oz = 3.18 kg
• ▶ 7 lbs 8 oz = 3.40 kg
• ▶ 8 lbs 0 oz = 3.63 kg
• ▶ 8 lbs 8 oz = 3.86 kg
• ▶ 9 lbs 0 oz = 4.08 kg
• ▶ 9 lbs 8 oz = 4.31 kg
• ▶ 10 lbs 0 oz = 4.54 kg

Average Newborn Weights

According to the World Health Organisation, the average full-term newborn weighs:

• ▶ Girls: 3.2 kg (7 lbs 1 oz)
• ▶ Boys: 3.3 kg (7 lbs 4 oz)
• ▶ Normal range: 2.5 to 4.5 kg (5 lbs 8 oz to 9 lbs 15 oz)

Converting Pounds and Ounces to Kilograms

Baby weights in the US are expressed in pounds and ounces (e.g., "7 lbs 6 oz"). To convert this to kilograms:

1. Convert everything to ounces: (7 × 16) + 6 = 118 oz
2. Multiply by 28.35 to get grams: 118 × 28.35 = 3,345 g
3. Divide by 1000 to get kilograms: 3.35 kg

Why It Matters

• ▶ Medical records — paediatricians track growth in the metric system for WHO growth charts
• ▶ Medicine dosing — infant medications are dosed per kilogram of body weight
• ▶ International families — grandparents abroad may only understand one system
• ▶ Growth percentiles — growth charts use kilograms, so you need accurate conversions

Tracking your baby's weight gain is one of the best indicators of healthy development in the first year. Whether your doctor uses kg or lbs, now you can understand both.