Free tool

Queen cell calculator

You have opened a hive and found queen cells. This works out the dates that follow: when the cell seals, when the virgin comes out, how long to keep your hands off, and when there should be eggs. Every number is taken from a published source, and each one is named.

What did you see?

Pick the one that matches the cell in front of you. If several cells are at different stages, use the one that is furthest along, because that is the one setting your deadline.

An egg standing in a queen cupA queen cup with an egg standing in it. Normal, and not a decision the colony has made yet.A larva in royal jelly, cell not sealedA cup drawn out into a cell with a fat larva sitting in a pool of royal jelly. This one is going the whole way.A sealed queen cellClosed over, usually shaped like a peanut. Sealed tells you the least about timing of any of these.A cell she has already come out ofAn opened cell with a hinged lid, or the tip cut away. She is out.

The day you saw it

Unsealed cells with larvae in them mean you have days rather than weeks, and you still have choices about what to do. [WBKA]

Cell sealed
Fri, 4 Sept 2026 to Wed, 9 Sept 2026
The cell is sealed on day eight. A colony usually swarms at about this point, and sometimes before it. [WBKA]
Virgin emerges
Sat, 12 Sept 2026 to Thu, 17 Sept 2026
She comes out on day sixteen, eight days after the cell is sealed. [WBKA]
Do not open it before
Sun, 27 Sept 2026
At least a fortnight, and not before there could be an egg to see even if she was slow. A virgin coming back from a mating flight to an open hive can end up in the wrong colony, or not get home at all. If you truly have to look, go after five in the afternoon, when she is more likely to be indoors. [BBKA]
Expect to see eggs
Tue, 22 Sept 2026 to Thu, 1 Oct 2026
Ten to fourteen days after she emerges, and longer in poor weather or in a big colony. Look for eggs, or for a patch of cells polished ready for her. [BBKA]
Still nothing? Ask someone local
Thu, 8 Oct 2026
Three weeks after she emerged with no eggs is the point to get a second opinion from your association rather than keep waiting. [BBKA]

Where these dates come from

Wally Shaw, Welsh Beekeepers’ Association, There are queen cells in my hive - what should I do?
British Beekeepers Association, Swarm Control for Beginners

There is no mating date here on purpose. Beekeepers ask for one, and we have not found a UK source we would stand behind for the day she flies. What the sources do support is the fortnight of leaving her alone and the window in which she starts to lay, and eggs are the thing you can actually see. A date we made up would be worth less than no date at all.

Weather changes all of this. A cold, wet fortnight delays mating and laying, and the dates above assume she gets flying weather.

Read these before you decide anything

A date is not a plan. What you do about the cells depends on why they are there, and the cells themselves tell you.

Queen cells, what you are looking at separates swarm cells from supersedure and emergency cells, which need different answers.
The artificial swarm, step by step is the method most UK associations teach when the cells are swarm cells.
Is the colony queenright? covers what to look for when the dates have run out and you still cannot see her.
Preventing swarming is the easier job, for next season.

Keep track of your queens

A free Bees Knees Apiary account records every queen against her hive, with her age, her marking colour and where she came from, so next spring you are not guessing which colonies are due a new one.

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