Kitchen Worktop Calculator

How Many Worktops Do I Need?

The usual way is to take each run on its own and divide it by the board length. For an L-shaped kitchen with runs of 3.6m and 2.8m, on 3m boards, that is 3 boards. It misses two things. At a corner, one run's worktop goes into the corner and the other stops at its front edge, 620mm short. And a short piece from one run can come out of the offcut of another.

So this calculator plans the cut. It tries each run going through each corner, splits any run longer than a board with the joint at least 100mm from the sink and hob cut-outs, and packs every piece into as few boards as it can. For the same kitchen, putting run B through the corner brings the other run down to fit a 3000mm board, so it needs 2 x 3000mm. In the table below the plan buys less worktop than the run-by-run count in 5 of 8 kitchens.

How the Plan Works

• One worktop through each corner. The other butts against its front edge (Howdens), so it is shorter by the worktop depth. Both directions are tried.
• Joints clear of the sink and hob. B&Q: joints at least 100mm from any sink or appliance cut-out. The corner counts as a joint: we keep cut-outs 100mm from the butt joint, and from the whole corner square on the run that goes through (our reading).
• Cut-outs away from the ends. Howdens: never closer than 60mm to the end edges of a worktop. The calculator warns you if one is.
• Offcuts reused. Pieces are packed into boards longest first, with a 3mm saw cut between them, and each board is the shortest length that holds its pieces.

What it does not do: it does not handle corners other than 90 degrees, breakfast bars, upstands or edging, and it does not know where your cabinet joints are. B&Q says not to put a worktop joint right over one.

Worktop Ranges, With Sources

Every length in the calculator has a merchant product page, and no product page means no length. Ranges differ in depth (600 or 620mm), and the depth is what a butting worktop loses at a corner.

Where the Rules Come From

The corner and cut-out rules are from Howdens' worktop installation guide (butting two tops in an L, cut-outs at least 60mm from the end edges, male and female mitre ends). The joint clearance is from B&Q's guide to fitting a kitchen worktop (joints at least 100mm from any sink or appliance cut-out). Treating the corner as a joint for the clearance, the 3mm saw cut, and the packing of pieces into boards are our own working.

Common Kitchens: Worktops Needed

Generated from the calculator above, with no cut-outs, on the Wickes square edge range (620mm deep). The run-by-run column counts each run on its own in 3000mm boards, which is the usual method.

Use the calculator for your own kitchen. Where the sink and hob sit can move a joint, and sometimes change which run should go through the corner.

Frequently Asked Questions

How many worktops do I need?

The usual way is to take each run on its own and divide it by the board length. For an L-shaped kitchen of 3.6m and 2.8m on 3m boards that is 3 boards. This calculator decides which run goes through the corner, takes the worktop depth off the other, keeps joints clear of the sink and hob, and cuts every piece from as few boards as it can, reusing offcuts. The same kitchen needs 2 x 3000mm. In the table below that is less worktop than the run-by-run count in 5 of 8 kitchens.

Which worktop goes through the corner?

Either can. At a 90 degree corner one worktop runs right into the corner and the other butts against its front edge, so the butting one is shorter by the worktop depth (620mm on the Wickes square edge range). Howdens' guide says that when butting two tops together in an L shape, the finished front edge is removed to take the adjoining end of the other worktop. The calculator tries both ways and keeps the one that needs the least board. In the default kitchen, run B goes through, which leaves run A at 2980mm. The other way round needs 1 x 4100mm + 1 x 3000mm.

Where can a worktop joint go?

B&Q's guide says joints between worktops should be at least 100mm away from any sink or appliance cut-out, and not right over a cabinet joint. Howdens says cut-outs for hobs and sinks should never be closer than 60mm to the end edges of a worktop. So when a run is longer than a board, the calculator puts the joint at least 100mm from the sink and hob cut-outs, as evenly as it can. For a straight 5m run with a sink from 2300mm, the joint goes at 2200mm. It does not know where your cabinet joints are, so check that yourself.

What lengths do worktops come in?

It depends on the range. Wickes' Natural Oak Effect square edge worktop is sold in 3000mm and 4100mm lengths, 620mm deep and 38mm thick. Its Blocked Oak Effect worktop is 3000mm long and 600mm deep. Each has a product page in the list below. A mix of lengths often wastes least: for a U of 2.4m, 3.0m and 2.4m, the two end pieces come out of one 4100mm board.

Does it use a mason's mitre or a butt joint?

Either joins the same two boards, so the count is the same. A mason's mitre is cut with a router and a worktop jig, and Howdens says to make sure the male worktop is sized to take the inset into the female one. Howdens gives no extra length for it, so the calculator adds none. Allow a little extra if you are new to using a jig.

Should I buy a spare board?

The plan cuts every piece from the boards shown, with a 3mm saw cut between pieces from one board. There is no allowance for a mis-cut, and worktops are expensive, so the offcut left over is worth checking before you cut. The results list every offcut.

What about upstands, end panels and breakfast bars?

Not counted. The calculator covers the worktop along the walls only. Howdens' guide also says the maximum unsupported overhang is 300mm and the maximum unsupported span is 600mm for its 22mm worktops, so an overhanging breakfast bar needs its own support.