Infant Growth Velocity Calculator

Work out infant growth velocity instantly with clear inputs, formula shown and shareable results.

About Infant Growth Velocity Calculator

Divides the weight change by the interval to give daily and weight-indexed growth velocity, the measure used to judge adequacy of feeding.

Formula

Growth velocity

Grams per day = (current weight - earlier weight) / days; grams per kg per day = grams per day / earlier weight in kg

Worked example

With the default values below, Infant Growth Velocity Calculator returns Weight gain of 21.4. Change any input above and every figure here is recalculated in your browser.

Inputs used

Earlier weightaccepts 300–20,000 g: 3,900 g
Current weightaccepts 300–20,000 g: 4,200 g
Days between measurementsaccepts 1–180: 14

Results

Weight gain: 21.4 g/day
Weight gain per kilogram: 5.49 g/kg/day
Weekly gain: 150 g/week

Step by step

1Values used
2Growth velocity
3Weight gain= 21.4 g/day
4Weight gain per kilogram= 5.49 g/kg/day
5Weekly gain= 150 g/week

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

What gain is expected?

Roughly 25 to 35 g a day in the first three months, falling to about 15 to 20 g a day by six months.

Why index to weight?

Preterm growth targets are expressed as 15 to 20 g/kg/day, which accounts for the baby's starting size.