Puppy feeding and growth
When do puppies grow the fastest?
Last updated 23 September 2026 · How we write and check this
Short answer
Puppies typically grow fastest, relative to their eventual adult size, in the first few months of life, roughly 2 to 5 months for most breeds. Large and giant breeds often keep growing at a meaningful pace for much longer than small breeds do.
The early months carry the most relative growth
A puppy gains a larger percentage of its total adult weight in its first few months than in any later stretch of the same length, which is why calorie needs per kilogram of body weight are highest during this window and drop off steadily afterward.
How the fastest window differs by size
Small breeds pack most of their growth into a shorter overall period, so their fastest phase is compressed into roughly the first four months. Large and giant breeds spread their growth over a longer total time, so while they also grow fastest early on, meaningful growth continues well beyond what a small breed experiences.
Why this matters for feeding
Because calorie needs are highest during the fastest growth window, this is when underfeeding has the biggest impact, and when portions typically need the most frequent recalculating, often every one to two weeks rather than monthly.
Key takeaways
- Puppies grow fastest, relative to adult size, in roughly their first 2 to 5 months.
- Small breeds compress most of their growth into a shorter overall window.
- Large and giant breeds continue meaningful growth well beyond that early period.
- Food portions typically need the most frequent adjusting during the fastest growth phase.