Weight Chart for 1-Month-Old Boys
Selected body weight percentiles for boys at 1 month, reported in kilograms and pounds from the cited official reference table.
WHO percentile table
| Percentile | Metric | US customary |
|---|---|---|
| 3rd | 3.4 kg | 7.5 lb |
| 5th | 3.6 kg | 7.9 lb |
| 10th | 3.8 kg | 8.4 lb |
| 25th | 4.1 kg | 9.0 lb |
| 50th | 4.5 kg | 9.9 lb |
| 75th | 4.9 kg | 10.8 lb |
| 90th | 5.3 kg | 11.7 lb |
| 95th | 5.5 kg | 12.1 lb |
| 97th | 5.7 kg | 12.6 lb |
What these numbers imply
The figures below are not published directly by the WHO. Each one is calculated from the official weight-for-age tables so that this page answers questions the raw dataset leaves open. Values differ for every age and sex.
| Measure | Value | How it was derived |
|---|---|---|
| Weight gain over the next 3 months | +2.5 kg | The 50th percentile rises from 4.5 kg to 7.0 kg over the following 3 months. Derived from adjacent rows of the same WHO table. |
| Weight gain since birth | +1.2 kg | The 50th percentile at birth is 3.3 kg; at this age it is 4.5 kg. |
| Spread between 3rd and 97th percentile | 2.3 kg | At this age the middle 94% of boys fall between 3.4 kg and 5.7 kg. |
| Difference from girls at the same age | +0.3 kg | The 50th percentile for boys is 0.3 kg heavier than that for girls. |
| Median length and resulting BMI | 54.7 cm · BMI 15.0 | Combining the 50th percentile of weight (4.5 kg) with the 50th percentile of length (54.7 cm) from the WHO weight-for-age and length-for-age tables. |
These are population reference statistics only. They describe how a group of children of this age and sex is distributed, and say nothing about any individual child.
How to read this table
For this table, a percentile is a position in the cited reference distribution for children of the same sex and completed age band. The 50th percentile is the median. These values are not a personal forecast, target, diagnosis, or recommendation.
Measurement: WHO reports weight for the exact week or month shown.
Adjacent ages
Height predictor
This reference table does not embed the calculator. Open the homepage height predictor separately.
Data source
Dataset: WHO Child Growth Standards (2006): boys weight-for-age, birth to 5 years. All displayed kilograms values come from tab_wfa_boys_p_0_5.xlsx, row Month=1. The pounds column is a direct unit conversion. See the official WHO dataset page.
Reference distribution only. This page does not provide medical advice, a diagnosis, or an individual forecast.