Rebar and Wire Mesh Calculator
Enter a slab's size, the bar size, spacing and cover and get rebar sticks cut from your stock length, with weight and wire mesh sheets by layout, rounded up once, with the working shown for an example slab. It counts layout only.
Estimates for planning, not professional advice. Read the full notice.
Example: a slab
10 sticks
- Bars in each direction 10 bars
- Length of each bar 9 ft 6 in
- Total bar length 190 ft
- Weight of the bar 126.9 lb
- Fewest sticks any cut plan could use 10 sticks
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Rebar sticks | sticks | 10 |
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Worked example: a slab
Show the working
- Spaces across: the width less cover both sides, over the spacing 9 ft 6 in ÷ 1 ft = 9.5 spaces
- Bars each way: whole spaces plus one 9 spaces + 1 = 10 bars
- Each bar: the length less cover both sides 10 ft − 6 in = 9 ft 6 in
- Total length: bars in both directions times each bar 20 bars × 9 ft 6 in = 190 ft
- Weight: total feet times pounds per foot 190 ft × 0.668 lb/ft[1] = 126.9 lb
- Sticks: bars cut from stock, offcuts shared, rounded up once 20 bars = 10 sticks
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|---|---|
| Rebar stock length | 20 ft | |
| Default Stock length is not sourced here. Check your label or supplier. | ||
| Rebar edge cover | 3 in | |
| Default Cover is a design choice, not a sourced fact. Check your label or supplier. | ||
| Wire mesh lap | 8 in[2] | |
| Default One mesh square plus the ASCC allowance; for 6 in mesh this is the default shown. | ||
| Wire mesh sheet (width by length) | 7 ft × 20 ft | |
| Default Sheet size varies by maker and store. Check your label or supplier. | ||
| Weight per foot of #3 bar | 0.376 lb/ft[1] | |
| ASTM standard reinforcing bars #3 to #8: nominal diameter, area and weight per foot. | ||
| Lap length for #3 bar, CRSI Class B | 13 in[1] | |
| CRSI Table A1 tension lap splice length, Class B, bars other than top bars, for Grade 60 bar, 3,000 psi concrete, uncoated bar and 1.5 in cover (ACI 318-19). Other grades, strengths, coatings or covers give other lengths. | ||
| Weight per foot of #4 bar | 0.668 lb/ft[1] | |
| ASTM standard reinforcing bars #3 to #8: nominal diameter, area and weight per foot. | ||
| Lap length for #4 bar, CRSI Class B | 18 in[1] | |
| CRSI Table A1 tension lap splice length, Class B, bars other than top bars, for Grade 60 bar, 3,000 psi concrete, uncoated bar and 1.5 in cover (ACI 318-19). Other grades, strengths, coatings or covers give other lengths. | ||
| Weight per foot of #5 bar | 1.043 lb/ft[1] | |
| ASTM standard reinforcing bars #3 to #8: nominal diameter, area and weight per foot. | ||
| Lap length for #5 bar, CRSI Class B | 22 in[1] | |
| CRSI Table A1 tension lap splice length, Class B, bars other than top bars, for Grade 60 bar, 3,000 psi concrete, uncoated bar and 1.5 in cover (ACI 318-19). Other grades, strengths, coatings or covers give other lengths. | ||
| Weight per foot of #6 bar | 1.502 lb/ft[1] | |
| ASTM standard reinforcing bars #3 to #8: nominal diameter, area and weight per foot. | ||
| Lap length for #6 bar, CRSI Class B | 26 in[1] | |
| CRSI Table A1 tension lap splice length, Class B, bars other than top bars, for Grade 60 bar, 3,000 psi concrete, uncoated bar and 1.5 in cover (ACI 318-19). Other grades, strengths, coatings or covers give other lengths. | ||
| Weight per foot of #7 bar | 2.044 lb/ft[1] | |
| ASTM standard reinforcing bars #3 to #8: nominal diameter, area and weight per foot. | ||
| Lap length for #7 bar, CRSI Class B | 43 in[1] | |
| CRSI Table A1 tension lap splice length, Class B, bars other than top bars, for Grade 60 bar, 3,000 psi concrete, uncoated bar and 1.5 in cover (ACI 318-19). Other grades, strengths, coatings or covers give other lengths. | ||
| Weight per foot of #8 bar | 2.67 lb/ft[1] | |
| ASTM standard reinforcing bars #3 to #8: nominal diameter, area and weight per foot. | ||
| Lap length for #8 bar, CRSI Class B | 54 in[1] | |
| CRSI Table A1 tension lap splice length, Class B, bars other than top bars, for Grade 60 bar, 3,000 psi concrete, uncoated bar and 1.5 in cover (ACI 318-19). Other grades, strengths, coatings or covers give other lengths. | ||
Feet and inches, like 12' 6"
Sticks and offcuts for slabs of several sizes
Bars each way, length of each bar, splices, sticks cut from stock and the fewest possible, for square slabs with number four bar at twelve inch spacing
| Slab size | Bars each way | Length of each bar | Splices per bar | Sticks to buy | Fewest possible sticks | Weight of the bar |
|---|---|---|---|---|---|---|
| 10 ft | 10 bars | 9 ft 6 in | 0 splices | 10 sticks | 10 sticks | 126.9 lb |
| 16 ft | 16 bars | 15 ft 6 in | 0 splices | 32 sticks | 25 sticks | 331.3 lb |
| 20 ft | 20 bars | 19 ft 6 in | 0 splices | 40 sticks | 39 sticks | 521 lb |
| 24 ft | 24 bars | 23 ft 6 in | 1 splices | 60 sticks | 60 sticks | 801.6 lb |
Bars longer than a stick are lapped, and the offcut of one bar is used for another where it fits. The sticks never fall below the fewest possible, which is the total length over the stock length.
Wire mesh sheets by layout and by area
Sheets of the default size laid with laps, beside the count from the area alone, for square slabs
| Slab size | Sheets laid with laps | Sheets by area with laps | Sheets by area, no laps |
|---|---|---|---|
| 10 ft | 2 sheets | 1 sheet | 1 sheet |
| 12 ft | 2 sheets | 2 sheets | 2 sheets |
| 16 ft | 3 sheets | 3 sheets | 2 sheets |
| 20 ft | 4 sheets | 4 sheets | 3 sheets |
Laying whole sheets with their laps needs more sheets than the area alone suggests for some slabs. The sheet size and lap are inputs; check your sheets.
Questions
How many sticks of rebar do I need?
Type the slab's size, the bar size, the spacing and the cover. The calculator counts bars each way, cuts them from your stock length with offcuts shared and laps where a bar is longer than a stick, and rounds the sticks up once.
How much does the rebar weigh?
The weight is the total bar length times the pounds per foot of the bar size, from the CRSI table. The worked example shows it for one slab.
Why are mesh sheets more than the area suggests?
Whole sheets are laid with a lap where they meet, so a slab can need an extra sheet in each direction. The mesh table shows the layout count beside the count by area.
Where does the lap length come from?
From CRSI's tension lap table for Class B, for the bar you pick, under the assumptions that table states. Other grades, strengths, coatings or covers give other lengths, so type your own lap to replace it.
Sources (2)
-
CRSI 2025 Spring Product Catalog (opens in new tab), Concrete Reinforcing Steel Institute, 2025 Spring; lap values (Class B, other bars, 1.5 in cover) read from the table image on p. 16 of the CRSI catalog (2025 Spring); the PDF text layer is scrambled, so they are not in the quote.
Standards or industry body.
“Tension Development and Lap Splice Lengths for Uncoated and Galvanized Deformed Bars (in.) Code: ACI 318-19 ... Table A1: Grade 60, f´c = 3,000 psi ... Concrete Cover = 1.5 in. ... Lap Class: A = 1.0ℓd, B = 1.3ℓd”
“ASTM STANDARD REINFORCING BARS ... Bar Size Designation NOMINAL DIMENSIONS Area (in.2) Weight (lb/ft) Diameter (in.) #3 0.11 0.376 0.375 #4 0.20 0.668 0.500 #5 0.31 1.043 0.625 #6 0.44 1.502 0.750 #7 0.60 2.044 0.875 #8 0.79 2.670 1.000”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 1) -
WWR Lap Splice Requirements (The Voice newsletter) (opens in new tab), American Society of Concrete Contractors, Posted January 15, 2021.
Standards or industry body.
“In section 6.4, the lap splice indicated for plain wire WWR is one square, plus 2 inches.”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 2)
These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.
Sources
- [1] Concrete Reinforcing Steel Institute, CRSI 2025 Spring Product Catalog. Checked November 12, 2026. https://members.crsi.org/Common/Uploaded%20files/Promotional_and_Marketing/CRSI_Product_Catalog_2025-Spring.pdf
- [2] American Society of Concrete Contractors, WWR Lap Splice Requirements (The Voice newsletter). Checked November 12, 2026. https://ascconline.org/Home/News/articleType/ArticleView/articleId/51/WWR-Lap-Splice-Requirements