The parent colony brings 20 frames of brood/bees and about 2,000 bees per frame into the split. Each new nuc gets an equal share of the frames you allocate; if nucs × frames-per-nuc exceeds the parent's 20 frames, every nuc is scaled down proportionally instead — you cannot conjure bees that were never there.
A nuc needs roughly 1,500 bees at the moment of splitting to keep a queen cell warm through the ~16 days it takes a queen to emerge and start laying. Below that threshold the nuc has too few nurse bees to hold cluster temperature and rear a queen at all — its population just decays as its original workers age out over their ~6-week lifespan, and it never recovers.
A viable nuc still dips for its first two queenless weeks (no new brood is being laid yet), then the new queen's laying kicks in and the population climbs back up, following the same brood-cycle limit as any colony: a worker egg takes 21 days to become a forager, so buildup is gradual, not instant, and eventually plateaus near what the nuc's frame count can support.
- Number of nucs — how many ways the parent colony is split. More nucs means more chances to raise a new queen, but each gets a thinner share of bees.
- Frames per nuc — the brood/bee frames given to each nuc; the direct lever on whether it clears the 1,500-bee viability threshold.
- Weeks since split — scrub the timeline to see the buildup (or collapse) unfold.