Puppy growth calculator: plot weigh-ins and see where your puppy is heading

Why several weigh-ins beat one

Puppies don't grow in a straight line, and they don't wander randomly either. A puppy who is chunky for its age at 10 weeks is usually still chunky at 14. In our data, the error in a forecast made at one age and the error made three weeks later were strongly linked (a correlation of about 0.76). Put plainly, the second weigh-in mostly repeats what the first one already told you.

That's why the improvement has limits. Two weigh-ins a week apart add very little. Two weigh-ins a month apart add more. The calculator knows this: it weighs each reading using how closely related it is to the others, and it won't claim a tight range just because you entered ten numbers in one afternoon.

Reading the chart

• The black line and dots are your puppy's weigh-ins.
• The dashed green line is the typical curve for a dog that ends at the forecast weight.
• The green band is the 80% forecast range around that curve. It's wide at the start and stays wide if you only have one reading.
• The pale grey band shows how real puppies of that size spread out around the typical curve, from the 10th to the 90th percentile.

A puppy that sits inside the grey band isn't unusual. A puppy that starts inside and then crosses out of it, or that drops weight between readings, deserves a second look.

How often to weigh

Weekly is plenty for most puppies until about 6 months, then every two to four weeks. Toy breeds can be weighed more often because small changes are a bigger share of their weight, and a kitchen scale reads grams. Giant breeds grow for up to two years, so keep going with monthly weigh-ins after the first birthday. Vets weigh at every visit, so it's worth asking for the number.

Signs that growth is off the curve

Two things to watch. Weight loss in a puppy that's still growing is a reason to call the vet, particularly with vomiting, diarrhoea or low energy. And gaining much faster than the curve suggests matters in large and giant breeds, where too-fast growth can strain developing joints. The paid PupCurve tracker compares each new weigh-in with the curve and flags a puppy that gained much more or less than typical for its size.

This isn't a diagnosis. Scales differ, a full bladder weighs something, and one odd reading is often just that. Look for a pattern across two or three weigh-ins.

How to use it, step by step

1. Collect the weigh-ins. Gather dated weights from your vet visits, breeder paperwork or your own scale.
2. Enter each age and weight. Use the Add weigh-in button for each reading. Age can be in weeks or months.
3. Choose a breed if known. A breed narrows the range, especially with few weigh-ins.
4. Read the forecast and chart. Compare the dots with the dashed typical curve and the shaded range.
5. Keep weighing. Weigh weekly to 6 months, then every few weeks. Save them in a free account.