Construction and Trade Calculators
Material quantities for building work: how much concrete, how many bags, how many boards — with the assumption behind every number spelled out.
The calculators
- Brick Calculator: How Many Bricks You Need
Work out how many bricks a wall needs from its area and brick size, with the coursing figures sourced and the manufacturer's minimum waste allowance.
- Concrete Bag Calculator: How Many Bags for a Slab
Work out how many bags of concrete mix a slab needs, plus the mixing water — with the yield per bag and its source spelled out.
- Concrete Block Calculator: How Many CMU Blocks, Courses and Mortar Bags You Need
Work out how many concrete blocks (CMU), courses and masonry cement bags a wall needs, with the CMHA/NCMA source figures spelled out.
- Deck Board Calculator: How Many Boards, Joists and Fasteners You Need
Work out deck board rows, joists and hidden fasteners from your deck size and board width, with the manufacturer spacing facts sourced.
- Drop Ceiling Calculator: Wall Angle, Main Tee, Cross Tees, Hanger Wire & Panels
Work out wall angle, main tee, cross tees, hanger wire and ceiling panels for a suspended drop ceiling, sourced from USG and Armstrong installation guides.
- Drywall Calculator: Panels, Tape, Compound and Fasteners
Work out how many drywall panels, how much joint tape and compound, and how many fasteners a wall needs — with the material rates and their source spelled out.
- Fence Post Concrete Calculator: How Many Bags per Post
Work out how many bags of fast-setting concrete mix your fence posts need from post and hole size and bag size, with the manufacturer method sourced.
- Grout Calculator: Grout Volume and Bags Needed
Calculate grout volume in cubic inches from tile size and joint dimensions, then work out how many bags you need from your own coverage rate.
- Mortar Bag Calculator: How Many Bags for Block or Brick
Work out how many masonry cement bags and how much sand a block or brick wall needs, with the manufacturer yield spelled out and sourced.
- Mulch Calculator: Bags Needed by Area & Depth
Calculate the mulch volume from area and target depth, then work out how many bags you need from the bag size printed on your own product.
- Paver Calculator: How Many Pavers, How Much Sand and Edge Restraint You Need
Work out how many pavers, how much bedding sand and how much edge restraint your paved area needs from area and paver size, with ICPI/ASTM sourcing.
- Rebar Calculator: How Many Bars, Splices and Pounds of Steel You Need
Work out how many rebar bars, splices and pounds of steel a slab or wall needs, with Ohio DOT's specification tables sourced.
- Retaining Wall Block Calculator: Blocks, Capstones, Corners, Gravel & Geogrid
Work out blocks, capstones, corner blocks, gravel and geogrid rolls for a concrete block retaining wall, sourced from Allan Block's own installation guide.
- Shingle Bundle Calculator: How Many Bundles for a Roof
Work out how many shingle bundles a roof needs from its footprint and pitch, with the bundle coverage and trim-waste range spelled out and sourced.
- Soffit Vent Calculator: Required Ventilation Area and Panels Needed
Work out the IRC R806.2 required net free ventilation area for your attic, then how many vented soffit panels and linear feet you need to cover it.
- Stud Calculator: Wall Framing Studs, Plates & Openings
Work out field, corner and opening studs plus sole and double top plate length for a wood-framed wall, sourced from IBC Section 2308.9.
- Tile Mortar Calculator: How Many Thin-Set Bags You Need
Work out how many bags of thin-set mortar your tile job needs from area, product and trowel notch size, with each coverage figure sourced.
- Topsoil Calculator: Bags Needed by Area & Depth
Calculate the topsoil volume from area and application depth, then work out how many bags you need from the bag size printed on your own product.
- Wallpaper Calculator: Rolls Needed by Wall Size & Pattern Repeat
Calculate the number of wallpaper rolls needed from wall perimeter, ceiling height, your own roll size, and the pattern repeat.
Guides
- What the ASTM Paver Size Limit Means in Practice
Understand the ASTM C936 surface-area hint, large-format paver entries, bedding sand, and the calculator's worked paver example.
- When the 1/300 Attic Ventilation Exception Applies
Learn when IRC R806.2 permits the 1/300 attic ventilation ratio and how its required vent area compares with 1/150.
- Why a Wallpaper Roll Is a Confusing Purchase Unit
A wallpaper roll is not one universal size, and a bolt is not automatically a single roll. Learn what to measure before ordering.
- Why Corner Framing Is Not a Regular Stud Count
Understand why corner studs are counted separately, how the IBC corner wording differs from T-intersection practice, and how the calculator totals both.
- Why Diagonal Decking Needs More Joists
Trex requires tighter joist spacing for diagonal deck boards. See why, how clips follow the joists, and a worked layout example.
- Why Drop Ceiling Panels Get No Waste Allowance
USG's 5% allowance covers suspension materials, not panels. Learn why panel counts follow grid positions and see a full room example.
- Why More Mulch Is Not Always Better
Learn why mulch depth matters, how to re-mulch without overbuilding the layer, and why bag volume must come from your product label.
- Why Fence Post Concrete Is Hole Volume Minus Post Area
See why post-hole concrete is calculated as hole area minus post area, then minus the soil zone, with a transparent bag-count example.
- Why Rebar Lap Length Is Material You Buy, Not a Free Joint
Ohio DOT rebar weights and lap lengths show why every splice adds steel, weight, and stock bars to a real purchase.
- Why Retaining Wall Block Counts Include a Buried Course
The retaining wall calculator adds buried embedment before counting courses. Here is why that hidden row of block matters for planning.
- Why the Same Tile Job Needs Different Mortar Bag Counts
See why thin-set bag counts change with the product and trowel notch, using manufacturer coverage figures for the same tiled area.
- Why There Is No Single Bricks-per-Square-Foot Number
Brick counts depend on format: see why a flat bricks-per-square-foot rule hides the sourced coursing figure and waste allowance.
- Why There Is No Single Grout Coverage Number
Grout coverage depends on the product, tile format, joint width, depth, and job conditions—not one universal number for every bag.
- Why This Topsoil Calculator Skips a Fixed Density
Learn why topsoil bulk density is not a fixed bagging constant, how depth guidance works, and how the calculator turns volume into bags.
- Why Wall Thickness Does Not Change the CMU Block Count
Learn why CMU count uses block face dimensions, not wall width, and how purchase waste differs from blocks actually laid.
- Drywall Joint Compound: The 0.9-Gallon Rate a Popular Table Gets Wrong at One Row
Lowe's own drywall estimator implies 0.9 gal per 100 sq ft of joint compound — except one row, which breaks that rate.
- Mixing Block and Brick in One Wall: Why the Bag Count Isn't in the Data Sheet
QUIKRETE's yield figures cover block or brick, never both together — what adding them for a mixed wall assumes.
- What ARMA's Public Documents Actually Say About Shingle Waste
A '15% waste, per ARMA' figure for shingles doesn't appear in ARMA's own public bulletins — the checked primary source instead names 2-10%, tied to roof shape.
- Choosing a Concrete Bag Size: Fewer Big Bags or More Small Ones?
The same slab in 40, 50, 60, 80 or 90 lb bags: how the sack count and the total weight you carry change, worked out for one example pour.