Methodology

Breed data

Height, weight and life expectancy ranges for 277 breeds come from American Kennel Club breed data. Where the AKC gives no range, we use the typical range for the breed's size class and say so on the page. Size classes are set by maximum adult weight: toy under 5.5 kg, small to 13 kg, medium to 25 kg, large to 45 kg, giant above.

Population lifespans are shown where a breed appears in one of two UK studies: life expectancy at birth from VetCompass life tables (Teng 2022; 18 breeds; 30,563 deaths in 2016–2020) and median lifespan from McMillan et al. 2024 (584,734 dogs, 155 breeds; the longest- and shortest-lived breeds). UK and US populations differ, so the two figures on a breed page can disagree; we show both rather than blend them.

Health watchlists

110 breeds have a curated list of conditions with an established breed association, drawn from breed club health surveys, OFA statistics and the veterinary literature. The remaining breeds show a size-class list, labelled as such. Lists are not prevalence data and not diagnoses; they are what to screen for.

Formulas

• Dog age in human years. Size-adjusted chart: year 1 = 15, year 2 = 24, then +4 per year (toy and small), +5 (medium), +6 (large), +7 (giant). Epigenetic clock: human age = 16 × ln(dog age) + 31 (Wang 2020, Labradors).
• Life stages. AAHA 2019: senior = last 25% of expected lifespan; we set mature adult at 35% and puppy at 1 year (1.25 large, 1.5 giant).
• Lifespan estimate. Breed range plus additive adjustments: female +0.3 (Teng 2022: 11.41 vs 11.07); neutered +1.0 (Teng 2022: neutered vs entire by sex; Hoffman 2013); lean +0.5 (Kealy 2002: +1.8 vs free-fed controls, discounted because controls were above ideal); overweight −1.5 and obese −2.5 (Salt 2019: 5 months to 2.5 years). Additive population effects applied to a range; not a prediction.
• Calories. RER = 70 × kg^0.75 (NRC 2006). Multipliers: puppy under 4 months 3.0; 4–12 months 2.0; intact adult 1.8; neutered adult 1.6; inactive 1.3; senior 1.4; weight loss 1.0; active 2.5 (WSAVA).
• Ideal weight. Each body condition point above 5 on the 9-point scale ≈ 10% excess body weight (Laflamme 1997). Ideal = current ÷ (1 + 0.1 × (BCS − 5)).
• Puppy growth. Fraction of adult weight by age from piecewise curves per size class, adapted from Hawthorne et al. 2004. Adult weight = current ÷ fraction.

Limitations

Breed ranges are standards, not measurements. UK studies may not transfer to other countries. Lifestyle effects are correlations from observational cohorts (except Kealy 2002, a controlled trial) and are confounded by owner behavior. Calculators give starting points; your veterinarian gives advice about your dog.

Updates

Data files are versioned and rebuilt from source. Corrections: email us with the breed and the source.