GROWING UP WITH FITWARM

Puppy Weight & Growth Calculator

Your little one

months

1–24 months. Half months are welcome.

Weight unit
lb

0.2–550 lb.

Refine the fit with measurements

Enter snug body chest girth without extra room. We add 2.5 cm for comfort. Back length, from neck base to tail base, helps check coverage.

Measurements (optional)
Measurement unit

1–100 in.

ROOM TO GROW

Good to know
as they grow.

How is adult weight estimated?

The calculator divides your puppy’s current weight by an approximate growth fraction for their age and size group. Breeds select a starting group; you can adjust it for your puppy’s parents or mixed-breed background.

Fitwarm’s simplified planning curves reach adult size around 10, 12, 15, 18 and 24 months for toy, small, medium, large and giant dogs. The planning range is ±30% before 4 months, ±20% during early growth and ±15% later, with the lower estimate never below current weight. These are heuristic ranges, not statistical confidence intervals or clinically validated growth standards.

One weigh-in cannot establish a growth trend. Recheck with new measurements as your puppy grows.

How are the Fitwarm sizes selected?

Fitwarm’s charts list garment dimensions. We add 2.5 cm to body chest girth, then compare it with the garment chest chart. Back length helps check coverage and does not increase the suggested size. This keeps chest fit first for long-bodied and broad-chested dogs, including Dachshunds and French Bulldogs. Without a chest measurement, a rough body-size model estimates chest girth from weight and shows a broader size range.

Adult sizing is a planning reference only. When measurements are provided, body measurements are scaled with the cube root of the projected weight ratio before adding 2.5 cm of chest room; puppy proportions can change. Dresses use a different chart from pajamas, shirts and cold-weather clothes. Bikini sets, hats, harnesses and other accessories are excluded.

See the full Fitwarm size charts

What if my puppy is between sizes?

Prioritize the widest part of the chest and follow the exact product’s chart. If between sizes, choose the larger one. Check that your puppy can walk, sit and lie down comfortably. Avoid buying an oversized adult outfit for a growing puppy.

How should I follow my puppy’s growth?

Keep regular weight records and discuss changes with your veterinarian. This page shows a projection from one weight, rather than a record of observed growth. Puppies younger than 4 months and mixed breeds have especially uncertain estimates.

For clinical growth tracking, see WALTHAM’s puppy growth resources. General maturity context: Royal Canin’s guide to adulthood. These resources provide background; they do not validate or endorse this calculator.