You can estimate how old a baby rabbit is by looking at a few key physical and behavioral milestones, especially in the first few weeks of life.

Quick age clues (newborn–4 weeks)

  • 0–5 days old:
    • Eyes are closed and ears are folded flat against the head.
* Very small, often only slightly larger than a golf ball when cupped in your hand.
  • 5–10 days old:
    • Thin fur starts to appear; they are still mostly pink and tiny.
* Eyes may still be closed or just beginning to open.
  • 10–14 days old:
    • Eyes are fully open; ears may be starting to lift but still mostly down.
* They are noticeably fluffier and may begin to wriggle around the nest more.
  • 2–3 weeks old:
    • Ears are standing up; they start hopping short distances and exploring outside the nest.
* Size is roughly that of a large egg or small apple when cupped.
  • 3–4 weeks old:
    • Actively hopping, nibbling on hay and solid food; still very small but clearly mobile.

Beyond 4 weeks (weaning to adulthood)

  • 4–8 weeks:
    • Fully weaned from milk; eating hay, pellets, and some greens.
* Size and weight depend on breed, but they look like “mini” versions of adults.
  • 3–6 months:
    • Rapid growth; they reach most of their adult size and may start showing sexual maturity (e.g., mounting, spraying).
  • 6+ months:
    • Growth slows; it becomes much harder to guess exact age without records.
* Vets often estimate by teeth wear, coat quality, nails, and overall condition.

Simple “golf‑ball vs egg” rule (wild or unknown‑origin bunnies)

Many wildlife‑care guides suggest:

  • Smaller than a golf ball in your hand: Likely under 1 week.
  • Bigger than a golf ball but smaller than a large egg: Roughly 1–2 weeks.
  • Bigger than a large egg: Usually 2–3 weeks or older.

When to call a vet or rehab

  • If the baby is cold, limp, injured, or clearly orphaned, seek a rabbit‑savvy vet or wildlife rehabilitator immediately.
  • Never assume a wild nest is abandoned; many mother rabbits only visit briefly at dawn and dusk.

If you tell me what your bunny looks like (eyes open? ears up? size in your hand?), I can give a more specific age estimate.