Wire Mesh to Rebar Equivalents: Conversion Guide

To convert welded wire mesh to rebar (or the other way), match the steel area per metre of width, then check that the result is a layout the slab can actually use. The most common mesh, 152x152 MW18.7xMW18.7 (6x6 6/6), carries about 124.5 mm² per metre each way. A 10M grid at 300 mm carries about 333 mm²/m, more than two and a half times as much. That gap is why the light mesh styles have no sensible rebar equivalent bar for bar, and why heavier rebar specs only convert to heavy or engineered mesh.

How the conversion works

Both products are compared on cross-sectional area of steel per unit width of slab, in each direction.

• Rebar: area per metre = bar area (mm²) x 1,000 / spacing (mm). 10M is 100 mm², so 10M at 300 mm gives 100 x 1,000 / 300 = 333 mm²/m.
• Mesh: area per metre = wire area (the MW number, in mm²) x 1,000 / wire spacing (mm). MW18.7 at 152 mm gives 18.7 x 1,000 / 152 = 123 mm²/m. Published tables show 124.5 because they work from the exact 6 in spacing.

In US units the same idea is square inches per foot of width. Multiply in²/ft by about 2,117 to get mm²/m.

If the mesh style names are unfamiliar, our post on welded wire mesh sizes and designations explains the MW, W and gauge systems.

Mesh to rebar equivalent chart

Steel areas below are from the Reinforcing Steel Institute of Canada (RSIC) Manual of Standard Practice for standard construction mesh. The last column is the 10M spacing that would give the same area per metre, rounded.

Read the last column carefully. For the light and common styles, the "equivalent" 10M spacing is far wider than any slab detail would show. CSA A23.3 caps the spacing of reinforcement in slabs; the 2004 edition, for example, limits minimum slab reinforcement to the smaller of five times the slab thickness or 500 mm, and principal bars are capped tighter still (see our guide to maximum rebar spacing). So the honest answer to "what rebar equals 6x6 6/6 mesh" is: no practical rebar layout carries that little steel. A rebar alternative will be a light grid such as 10M at 400 or 450 mm, which carries noticeably more steel than the mesh.

Only the heavier styles, 6x6 2/2 and up, line up with real 10M spacings.

Rebar to mesh equivalent chart

Going the other way is the more common request: the drawings show a rebar grid and someone wants to know what mesh would match it. The table picks the lightest standard style with at least the same area each way, on area alone.

Beyond about 10M at 400 mm, standard construction mesh runs out. The RSIC manual lists engineered structural welded mesh made with much larger wires, including deformed (MD) wire as big as a 10M or 15M bar, which can match heavier rebar grids. That product is ordered to a design, not picked off a shelf.

Can you credit mesh's higher strength?

Mesh wire is stronger than rebar. Per the RSIC manual, citing ASTM A1064, smooth welded wire fabric has a minimum yield strength of 450 MPa and deformed structural wire fabric 485 MPa, against 400 MPa for the 400W bar used on most Ontario jobs.

The RSIC manual gives a conversion for deformed mesh on that basis: multiply the rebar steel area by 400/485 (about 0.825) to get the deformed mesh area needed. On that basis, 10M at 200 mm (500 mm²/m) would convert to about 413 mm²/m of deformed mesh.

Whether that reduction applies on your job is a design decision, not a site one. The designer has to be satisfied that the code allows the higher strength to be used for that element, that the mesh can be developed and spliced, and that crack control and spacing still work. When in doubt, convert on area alone, which is the conservative direction.

US equivalents: in² per foot

US slab details often give mesh as 6x6 W2.9xW2.9 and rebar as #3 or #4 at a spacing in inches. Areas in in²/ft:

So 6x6 W2.9 mesh is roughly the steel of #3 at 24 in, and #4 at 18 in carries more than twice as much. When a US detail is being built in Ontario, the engineer restates it in Canadian bars; our rebar area and spacing table and Canadian vs US rebar sizes post make that quick.

Area is not the whole story

Two slabs with the same steel area per metre can perform very differently. Before treating any conversion as a straight swap:

• Position decides whether the steel does anything. Mesh laid on the ground and "hooked up" during the pour usually ends up at the bottom of the slab, where it does little. Without other instructions from the designer, the RSIC manual places a single layer of mesh at mid-depth in slabs under 150 mm thick. Rebar on chairs holds its height far more reliably. Our post on wire mesh vs rebar for concrete slabs goes into this.
• Laps work differently. Mesh laps rely on the cross wires inside the lap; rebar laps rely on bar length. Converting changes the lap details and the quantity you order.
• Wire size affects crack control. Many small wires at close spacing control shrinkage cracks differently from fewer, larger bars.
• Mesh is not rebar. "Rebar mesh" is sometimes used for prefabricated mats of actual reinforcing bar, which is a different product again. Our post on what rebar mesh is sorts out the terms.

For a house slab on ground, the 2024 Ontario Building Code's Part 9 does not require mesh or rebar at all, so the choice comes from the designer, the specification or the contractor's preference. Where a slab is engineered, any conversion goes to the engineer for approval. For the cost side of the decision, see wire mesh vs rebar cost compared.

Switching a slab to rebar

If your drawings or engineer call for a rebar grid instead of mesh, or you want a rebar option priced against a mesh spec, we can help with the rebar side. We detail, cut and tag 10M to 55M rebar to your bar list and deliver across the GTA and Ontario, with laps and edge bars counted so the tonnage is real.

Send us your slab drawings for a free take-off and quote, or see our rebar products.