Growth Chart Calculator

The WHO standards (2006) describe how healthy, breastfed children grow in optimal conditions across six countries, including India. More than 100 countries use them for children from birth to 5 years.

The growth charts in your child's Singapore Health Booklet may be based on different reference data, so a percentile there can differ slightly from the one here. That's normal. Compare like with like, and look at the shape of the curve rather than a single number.

• Weight: use the same scale each time. For babies, weigh yourself holding your baby, then subtract your own weight. Clinic weights are better still. Weigh without clothes or a nappy when you can.
• Length (under 2): measured lying down, which really needs two people and a firm, flat surface. Home lengths are often a centimetre or two out, so clinic measurements are best.
• Height (from 2): standing, heels together, against a wall, without shoes.
• Head circumference: around the widest part of the head, just above the eyebrows and ears.

Always record the date of the measurement, not the date you enter it. Age matters a lot in the first months.

Each shaded band shows where most healthy children sit. The darker band is the 15th–85th percentile and the lighter band the 3rd–97th. The middle line is the 50th percentile: the average, not a target.

Children naturally sit anywhere across these bands. What doctors look for is the shape of your child's line: does it follow roughly the same curve over time? A baby on the 9th percentile who stays there is growing just as well as a baby on the 91st who stays there. Weight can wobble with illness or teething, so look at the trend across several measurements rather than one point.

If your baby was born before 37 weeks, the chart uses corrected age (their age counted from your due date) until 24 months. A baby born 8 weeks early who is 6 months old is plotted as a 4-month-old. Without this correction, many premature babies would look small simply because they started growing outside the womb earlier.

Measurements taken before your baby reaches 40 weeks' corrected age are listed but not plotted, because the WHO standards start at term. Your care team uses special preterm charts for that period.

The chart gently flags patterns that are worth mentioning at your next check-up. None of them is an emergency:

• a measurement below the 3rd or above the 97th percentile;
• weight dropping across centile lines between measurements. Following UK NICE guidance, the threshold depends on where your baby started: one line if they began below the 9th percentile, two lines from the middle range, and three lines if they began above the 91st;
• a fast rise across two or more lines.

Seek advice sooner if your baby is feeding poorly, has fewer wet nappies, seems unusually sleepy, or you're simply worried.

The WHO standards were built from healthy, breastfed children in six countries, including India, so they describe how children should grow in good conditions. Formula-fed babies are plotted on the same charts; some may gain a little faster in the first year, which is not necessarily a problem.

Weight alone doesn't tell you whether a child is in proportion. Weight-for-length (under 2) and weight-for-height (2 to 5) compare weight with a child's size rather than their age, which helps spot a child who is thin or heavy for their build. BMI-for-age does something similar but also accounts for age, because healthy body fat changes a lot in the early years. Babies naturally get chubbier in the first year, then slim down as toddlers start moving.

The chart includes all of these. If weight-for-length or BMI is outside the usual range while weight-for-age looks normal, it's worth mentioning to your doctor.

Babies don't grow in a perfectly smooth line. Growth spurts, illness, teething, starting solids and becoming more mobile can all cause short-term changes. Some babies also shift percentiles in the first months as they settle onto their genetic curve, especially if they were large or small at birth. A single dip followed by recovery is common; a sustained shift across lines is what your doctor will want to know about.