Puppy Growth Calculator

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Compare two puppy weigh-ins to calculate the weight change and average change per week. This tool tracks measured growth; it does not predict adult weight or height.

Earlier weigh-in
Later weigh-in

Enter ages at the time of each measurement. Use the same scale when possible. Values are not saved when you leave or reload this page.

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How to use the growth calculator

  1. Select Weight unit.
  2. Under Earlier weigh-in and Later weigh-in, enter the age in weeks and the measured weight.
  3. Press Calculate to see the weight change. Enter new measurements and calculate again to compare another interval.

What the results mean

Weight change is the later weight minus the earlier weight. Average weekly change divides that difference by the weeks between measurements. Change from earlier weight expresses the difference as a percentage of the earlier weight.

For example, 12 lb at 12 weeks and 16 lb at 14 weeks means 4 lb gained over 2 weeks: an average of 2 lb per week and a 33.33% increase. This is a description of those measurements, not a rate to aim for or extend into the future.

Looking for your puppy's adult size?

This page does not estimate adult weight or shoulder height. For that question, use WALTHAM's puppy growth charts or discuss your puppy's growth record with your vet. WALTHAM describes a conditional adult-weight estimate using three measurements two weeks apart after 12 weeks, with a chart selected for sex and expected adult-weight category. It is still an estimate, not a guarantee.

Limits of a two-point comparison

Two weigh-ins show a change in weight, not whether growth is healthy or what the puppy will weigh as an adult. Scale differences, meals and measurement timing can affect the comparison. A decrease is reported as a loss rather than hidden; if your puppy is losing weight or seems unwell, ask your vet for advice.

Age can include a decimal: for example, 12.5 weeks. Both measurements must use the same weight unit; changing Weight unit converts the weights already entered. The calculation uses the full entered values and rounds results for readability.

Calculation method

  • Weight change = later weight − earlier weight.
  • Weeks between measurements = later age − earlier age.
  • Average weekly change = weight change ÷ weeks between measurements.
  • Percentage change = 100 × weight change ÷ earlier weight.

The arithmetic above uses only your measurements. It does not apply breed, parent-weight, sex or height multipliers.