Block Paving Calculator

How Many Blocks of Block Paving Do I Need?

The usual answer is 50 blocks to the m² for a 200 × 100mm block, plus 10% or more. For a 5m × 4m area that is 1100 blocks, or 3 packs of 488. It says nothing about the pattern or the edges.

So this calculator lays the pattern out. It draws the herringbone or stretcher bond over the whole area, clips it to the edges, and counts every block as whole or cut. It tries every way of starting the pattern on the 100mm grid and keeps the one that needs the fewest blocks. For the same area that comes to 1000 blocks with the herringbone square to the edges, 1000 in stretcher bond and 1089 at 45 degrees, against 1100 from the rule of thumb.

No percentage is added on top, because the plan already counts every cut block. A spare pack is shown as its own line, like the architrave in the skirting calculator.

How the Layout Works

• Blocks on a 200 × 100mm grid. The packs listed below are exactly 50 blocks to the m², so the joint sits inside the block size. Marshalls says joints of 2-5mm.
• Three patterns. Herringbone with the blocks square to the edges, herringbone turned 45 degrees so the zigzag runs along the edges, and stretcher bond with each row moved half a block. Marshalls says areas with vehicles turning or braking should be laid in herringbone, and that basket weave is not for vehicles.
• Every block is whole or cut. The pattern is clipped to the area's edges. Marshalls says to lay whole units first, then cut units at edges and round obstacles.
• No piece under a quarter. Marshalls says no unit should be cut to less than a quarter of its size, and to use inboard cutting where only a small piece would fit. The calculator counts pieces under a quarter and warns you.
• Offcuts shared where the cut is straight. A short piece and the offcut of a longer one come out of the same block, and a piece can be turned round to fit an offcut (our rule). At 45 degrees the cuts are diagonal and we do not match offcuts, so it over-counts a little.
• Several areas. Up to four rectangles, laid separately.

What it does not do: it does not lay curves, borders or soldier courses, does not count edge restraints, and does not include the sub-base or sand. Use our sub-base calculator for the sub-base, and enter an L-shaped drive as rectangles.

Block Paving Sizes and Packs, With Sources

Blocks are 200 × 100mm and the thickness varies (50mm, 60mm and 80mm), but pack sizes differ by product. Every pack in the dropdown has a merchant product page that states the block size, the number of blocks and the pack coverage, and no product page means no dropdown entry. Check your own pack before ordering.

Where the Rules Come From

The laying rules are from Marshalls' installation details for standard concrete block paving (joints of 2-5mm, no unit cut to less than a quarter, inboard cutting, herringbone where vehicles turn, stretcher bond only in very lightly trafficked areas, no basket weave for vehicles, whole units first and cut units at edges, and blocks from the same batch drawn from at least three packs). The count for each pattern is our own working, from laying the pattern out and clipping it to your edges. The way offcuts are shared is also ours, and Marshalls does not describe it.

Common Areas: Blocks and Packs Needed

Generated from the calculator above. Each area is one rectangle on 200 × 100mm blocks, counted from the layout with nothing added. Packs are shown as stretcher / herringbone square / herringbone at 45 degrees, for the 488-block Wickes pack. The "area + 10%" column is the usual rule of thumb (50 to the m²) for comparison.

Use the calculator for your own area. The pattern changes the count more than you would expect.

Frequently Asked Questions

How many blocks do I need for block paving?

The usual sum is 50 blocks to the m² for 200 × 100mm blocks, plus 10% or more. For a 5m × 4m area that is 1100 blocks, or 3 packs of 488. It does not look at the pattern or the edges. This calculator lays the pattern over your area and clips it to the edges, so every block is counted as whole or cut. The same area needs 1000 blocks with the herringbone square to the edges, 1000 in stretcher bond and 1089 with the herringbone turned to 45 degrees.

How many 200 x 100 blocks are there in a square metre?

50. A 200 × 100mm block is 0.02 m², and the packs listed below are exactly 50 to the m²: Wickes' 488 blocks cover 9.76 m². Marshalls' datasheet for its Keyblok block gives a coverage of 50 per m². So the joint sits inside the nominal block size and is not added on top, and this calculator lays blocks on a 200 × 100mm grid.

Which laying pattern should I use?

Marshalls says areas with frequent vehicle turning, accelerating or decelerating should be laid in a herringbone pattern. Stretcher bond may be used in very lightly trafficked areas if the traffic direction is perpendicular to the laying pattern, and basket weave should not be used where vehicles drive. The calculator covers herringbone two ways and stretcher bond. It does not do basket weave.

How much cutting does herringbone need?

More than stretcher bond, and more again at 45 degrees. For the 5m × 4m area, the herringbone square to the edges has 44 cut pieces, and they come out of 22 blocks because pieces can share one. Turning it to 45 degrees makes 188 cut blocks, because every block along an edge is cut on the diagonal and we do not match the offcuts. The results and diagram show the counts for your own area.

What is the smallest piece I can cut?

Marshalls says no unit should be cut down to less than one quarter of its original size, to prevent looseness or dislodgement later. Where only a small section would fit, use the inboard cutting technique: a larger or full unit against the edge restraint, with a smaller unit placed in the resulting gap. The calculator counts how many edge pieces are under a quarter of a block and warns you.

How wide should the joints be?

Marshalls says a joint width of 2-5mm, varied slightly if needed to keep lines straight or maintain the bond, but never outside that range. Cut blocks should be cut so the resulting joint stays within it. The calculator does not count a piece thinner than 3mm, because that much can be taken up in the joints.

Are offcuts reused?

For stretcher bond and the herringbone square to the edges, yes. The edge cuts are straight across or along a block, so a short piece and the offcut of a longer one can come from the same block, and a corner piece cut both ways can go in another block's offcut, turned round if that fits. That is our own working, not a merchant rule. At 45 degrees the cuts are diagonal, and we do not try to match the offcuts, so every block along an edge counts as one block. That over-counts a little, and it is why the 45 degree figure is higher.

Should I order extra?

The answer here is the plan count, in whole packs, with no percentage added because the plan already counts every cut. A spare pack is shown on its own line (4 for the 5m × 4m area). Marshalls recommends that larger quantities all come from the same batch and are mixed on site by drawing from at least three packs, so it is worth ordering everything in one go.

Does it include the sub-base and sand?

No. It counts blocks only. For the sub-base, use our sub-base calculator, and for the laying course and jointing sand see Marshalls' installation details, which give a compacted laying course thickness of 30mm. Marshalls' guide also says edge restraints must be robust enough to resist lateral displacement.

What about curved or L-shaped areas?

Enter each rectangle as its own area. Each is laid separately and offcuts are shared between areas that use a straight-cut pattern. Where two rectangles join into one paved area that overstates the cutting along the join, so treat the count as a little generous. Curves, borders and soldier courses are not modelled.