Rebar & Wire Mesh Calculator
Lay out a rebar grid for a slab, or compare welded wire mesh sheets and rolls. Bar counts include edge cover; sticks include lap splices; weight uses ASTM A615 nominal weights.
Rebar & Wire Mesh Calculator — ConcreteNear.com
| Total length incl. laps | 546 LF |
| Bars running lengthwise | 14 · 19.5 ft each |
| Bars running widthwise | 14 · 19.5 ft each |
| Lap splice length | 20 in |
| Total weight | 365 lb |
| Tie points (intersections) | 196 |
| Chairs (about one per 3×3 ft) | 45 |
Cost estimate U.S. average prices
| Rebar, furnished & placed (by weight) 364.73 lb × $1.46 | $532.50 |
| Chairs 45 each × $0.60 | $27.00 |
| Estimated total | $559.50 |
- Buy about 5% extra bars for cuts and bends.
- Keep bars at mid-depth of the slab on chairs or dobies.
| Inputs | |
| Reinforcement | Rebar grid |
| Slab length | 20 ft |
| Slab width | 20 ft |
| Bar size | #4 (1/2 in) |
| Spacing (on center, both ways) | 18 in |
| Edge cover | 3 in |
| Stock bar length | 20 ft |
| Lap splice (bar diameters) | 40 |
Planning estimate only — confirm with your supplier or contractor.
Prices used — edit any price to match your local quote
| Item | Unit price | Basis & source |
|---|---|---|
| Rebar, furnished & placed per lb | public source Florida DOT Item Average Unit Cost 2025, item 0415 1 9 Reinforcing Steel – Approach Slabs (30 contracts) (2025 lettings) — DOT installed price on large public jobs. Retail bar-only prices for small orders are often higher per pound. | |
| Rebar chair / dobie per each | starting estimate Starting estimate. |
How to use this calculator
- Enter slab length and width.
- Pick bar size and spacing (e.g. #4 at 18 in on center).
- Set edge cover and stock length (20 ft is typical).
- Read sticks, weight, chairs and ties.
Formulas
Bars each way = floor((span − 2 × cover) ÷ spacing) + 1Bar length with laps: each extra stick adds a lap of (lap diameters × bar diameter)Weight = total length × lb/ft (#3 0.376, #4 0.668, #5 1.043, #6 1.502)
Questions
How much rebar do I need for a 20×20 slab?
#4 bars at 18 in each way with 3 in cover is 14 bars each way — 28 twenty-foot sticks, about 365 lb. The calculator gives the exact count.
What is a lap splice?
Where two bars overlap to continue a run. A common rule of thumb is 40 bar diameters (20 in for #4), but your plans or code govern.
Rebar or wire mesh?
Mesh is quicker for thin slabs; rebar gives more strength and is easier to keep in the middle of the slab on chairs.
Sources & assumptions
Prices checked 2026-11-10. State pricing multiplies national figures by the U.S. Bureau of Economic Analysis regional price parities (goods for materials, services for labor and services). RPPs compare general consumer price levels (U.S. = 100). They are not construction-specific; we use RPP Goods for materials and RPP Services: Other (excludes rents) for labor and services.
- Rebar, furnished & placed — Florida DOT Item Average Unit Cost 2025, item 0415 1 9 Reinforcing Steel – Approach Slabs (30 contracts) (2025 lettings). DOT installed price on large public jobs. Retail bar-only prices for small orders are often higher per pound.
Starting estimates No public price series was found for: Rebar chair / dobie; Welded wire mesh sheet (8×20 ft). These defaults are editable placeholders — replace them with a local quote.
Results are planning estimates, not quotes or engineering advice. Codes, specifications and your supplier's numbers govern.
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