How the Growth Chart Works

How the Calculation Works

The chart uses assessGrowthTracking(actualWeightKg, expectedWeightKg) from petCalculations.ts. It computes the ratio of your pet's actual weight to the expected weight for their age and breed, and classifies the result into one of three categories: 'on-track' (ratio between 0.85 and 1.15), 'above-average' (ratio above 1.15), or 'below-average' (ratio below 0.85).

In plain terms: if your pet's actual weight is within ±15% of what the growth curve predicts for their age, they're considered on track. A weight more than 15% above the expected value is flagged as above-average; more than 15% below is flagged as below-average. The ±15% band is deliberately generous to avoid over-flagging normal individual variation.

The expected weight at each age point is derived from the breed's growth curve in the breed profile data. For puppies, these curves reflect typical weight-at-age milestones scaled to the breed's expected adult weight. For kittens, the reference rate is approximately 0.45 kg (1 lb) per month for the first 4-5 months of rapid growth, then a slower taper toward adult weight by around 10-12 months.

Putting the Result into Practice

'On-track' means your pet's weight closely matches the expected value for their age and breed size -- the most reassuring result. Keep tracking monthly (or more frequently for very young animals) to confirm the trend continues.

'Above-average' can mean a few different things: a genuinely large individual within the breed, overfeeding, or a calculation using an adult size estimate that's smaller than your pet will actually be. For puppies, growing too fast relative to the curve can be a concern for large breeds, where excess early weight gain is linked to developmental joint issues.

'Below-average' warrants a closer look at feeding amounts and frequency. A kitten or puppy consistently tracking below the curve should be seen by a vet to rule out parasites, illness, or a diet that isn't meeting their energy needs.

Common Mistakes to Avoid

Using the wrong breed size category. The expected weight at each age scales with adult size -- using 'medium' for a breed that will actually be 'large' as an adult will make a healthy, fast-growing puppy look above-average when they're not.

Weighing on inconsistent scales or at different times of day. Young animals can vary meaningfully in weight before versus after a meal. Weigh at the same time of day, before feeding, for the most consistent comparisons over time.

Panicking at a single off-track reading. One data point outside the ±15% band is much less informative than a sustained trend. A single weigh-in after an unusually big meal, or a week of reduced appetite during a minor illness, can shift the number temporarily without indicating a real growth problem.

Applying the puppy growth chart past the age when the breed is approaching adult size. Once a breed has substantially completed its growth, the chart is no longer a useful comparison tool -- it's designed for the active growth phase.

Interpreting Your Result

On-track: your pet's growth is progressing as expected for their age and breed. Continue regular monitoring and keep feeding a complete, life-stage-appropriate diet.

Above-average: worth reviewing portion sizes and checking that you're using the right breed size category. For large and giant breed puppies especially, a vet conversation about growth rate is worthwhile -- controlled growth matters more for these breeds than for small ones.

Below-average: review feeding frequency and amounts for the life stage. If your pet is eating normally and still tracking below the curve, a vet visit to rule out underlying causes (parasites, infection, digestive issues) is the right next step.