Plaster Bead Calculator

How Many Angle Beads Do I Need?

The usual sum is one bead for each external corner and 3 for each window and archway: a side, the other side, and the head. For the default job, 2 corners, 3 windows and 1 archway, that is 14 beads, or 16 with 10% added. The cutting plan needs 9. In the table below the rule is over the plan on 6 of 6 jobs.

The sum treats every piece as a whole bead. But a 1200mm window side is half of a 2.4m bead, so the other half covers the next piece. The other shortcut, total metres over the bead length plus 10%, can go wrong either way: on the default job it gives 10 beads of 2.4m or 8 beads of 3m, and the cutting plan needs 9 on both. That is 1 too many on the first and 1 too few on the second. So this calculator lays out each piece and cuts it from the bead with the least room left.

How the Plan Works

• External corners. One piece the height of the ceiling for each corner you enter. Internal corners are usually taped, so none are added.
• Windows and archways. Bead on the head and both sides of each opening, cut to the opening size you enter. A door with a lining and architrave has no plastered reveal, so it needs no angle bead; a doorway or archway without a lining does. Switch on the sill option to add a bead along the bottom of each window.
• Stop bead. Enter each run as a length. Stop bead is packed on its own, since it is a different product.
• Offcuts reused. Pieces are cut longest first, each from the bead with the least room left that still fits it.
• No allowance for the cut. Bead is cut with tin snips, which take no length out. That is why two 1200mm pieces fit one 2.4m bead exactly, and why a bead with no length to spare is marked tight fit, no margin.
• No piece joined unless you switch joins on. Then no piece under 300mm is ever cut.

What it does not do: mitred reveal corners where a head bead meets a side bead, a gap left at the floor, arched or curved openings, and internal corners. For the plaster itself, see our plaster calculator.

Bead Lengths, With Sources

Every bead in the dropdowns has a Wickes product page. Galvanised bead is sold singly or in packs of 10, the PVC in packs as named.

The lengths are the merchant's. Where the bead goes, and cutting from the bead with the least room left, are our own working.

Common Jobs: Beads Needed

Generated from the calculator above. Ceilings are 2400mm, windows are 1200 x 1200mm unless stated and archways are 826 x 1981mm. Each cell is the number of angle beads: the usual sum, then the cutting plan on 2.4m beads and on 3m beads.

Frequently Asked Questions

How many angle beads do I need for a room?

The usual sum is one bead for every external corner and three for every window and archway (two sides and a head). For a room with 2 external corners, 3 windows and 1 archway that is 14 beads. Cut properly, with the offcuts used, the same job needs 9 beads of 2.4m. This calculator lays out every piece and shows both.

Why does the three-beads-per-window rule overcount?

Because a window reveal is three short pieces, not three full beads. Each side of a 1200mm window is 1200mm and the head is 1200mm, so two of them fit one 2.4m bead and a third goes in the next. The rule buys a whole bead for every piece. On the default job it says 14 and the cutting plan needs 9.

Where does angle bead go, and where does stop bead go?

Angle bead protects an external corner and gives the plaster a straight edge. Stop bead finishes the plaster where it stops against something else. This calculator puts angle bead on every external corner you enter and on the head and both sides of each window and each doorway or archway without a lining. A door with a lining and architrave has no plastered reveal, so it needs none. Stop bead is entered as runs of the length you need. That is our reading of common practice, so check it against your plasterer or the bead maker's guide for your job.

What length of bead should I buy?

Look at both the metres and the tight fits. On the default job 2.4m beads buy the fewest metres, 21.6m, but 6 of the 9 are tight fits. The length that buys the fewest metres with no tight fits is 3m: 9 beads of 3m, 27.0m in all, which is 5.4m more. A different job can come out the other way, which is why the calculator runs every length on sale and shows the table.

What does tight fit, no margin mean?

It means the pieces on one bead add up to exactly its length, with nothing spare. That is two 1200mm pieces on a 2.4m bead, or a 2400mm corner on a 2.4m bead. On the default job 6 of the 9 beads are like that. It works if the opening is exactly the size you entered and you cut exactly to length. If your window is 10mm bigger, the pair no longer fits and you need another bead, so measure first. 9 beads of 2.4m work only if your openings are exactly as entered. 9 beads of 3m leave room on every piece, for 5.4m more bead. Beads are cut with tin snips, which take no length out, so the calculator allows nothing for the cut.

Can I join beads?

You can, but the calculator keeps it off unless you switch it on. A bead that has to be joined to reach the ceiling leaves a joint in the corner, so it asks you to pick a longer bead first. With joins on, it never cuts a piece shorter than 300mm.

Do I need beads on internal corners?

The calculator does not add any. Internal corners are usually taped rather than beaded, so we leave them out. If yours needs bead, enter it as a stop run.

Does it cover render beads?

No. This calculator is for plastering inside the house. Render beads (corner, stop and bellcast) come in different lengths and materials, and they need a different set of inputs.