Preview only: this page is never built for production. Values come from the registry running real spec examples. Offers and ad slots are samples and link nowhere.
Header
The header as built: wide here, and a wordmark with a menu button when this panel is under 640px wide. Then the open phone menu, which fills the screen on a real phone (shown inside a phone-sized frame).
Normal, at its minimum (the − button is disabled), with help text, and invalid (a required size that is blank or 0: spruce outline, aria-invalid, described by the empty-state message).
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Quikrete: slabs are normally 4 to 6 inches thick depending on load; sidewalks at least 4 inches.
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Quikrete: slabs are normally 4 to 6 inches thick depending on load; sidewalks at least 4 inches.
Choice buttons
One selected, another selected, and a longer list that wraps.
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Extra for waste and spills
Ready-mix producers (NRMCA) advise ordering 4% to 10% more than the volume worked out from your plan.
Extra for waste and spills
Bag size
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Extra for waste and spills
Ready-mix producers (NRMCA) advise ordering 4% to 10% more than the volume worked out from your plan.
Extra for waste and spills
Bag size
Inline result bar
Real pages show it at 800px and below only; it is forced visible here. Second: the empty state.
The 10 x 10 ft patio example: checked (the date is a gallery sample; real cards use the tool's lastFactCheck), not yet fact-checked (a tool with no lastFactCheck), added to the project list, and empty (a required size is 0).
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You need
1.36cubic yards
includes 10% extra·1.04 m³
6280 lb bags
8260 lb bags
12340 lb bags
Add it to build one shopping list for your whole job.
Share this result: the link reopens it with your sizes
Wood stakes·about one every 3 feet of form, our estimate·often forgotten14
Wire mesh, 5 x 10 foot sheets·optional, allow extra for overlap2
Control joints·no more than about 10 feet apart; 6-8 feet for 4 inch walks
Project-type control
Tool pages show it only when two or more tools in the group have pages. Here every tool in the group is listed, the current one raised and the others real links.
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Live slab drawing
The 10 x 10 ft patio, and with no length yet. It redraws as the inputs change and has a text alternative.
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Redraws as you type·thickness exaggeratedRedraws as you type·thickness exaggerated
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Redraws as you type·thickness exaggeratedRedraws as you type·thickness exaggerated
Article section
The first article section of the concrete calculator, from the spec's copy.
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How thick should a concrete slab be?
A concrete slab is normally 4 to 6 inches thick, depending on the load it carries (Quikrete). A sidewalk should be at least 4 inches thick. A 10 by 10 foot slab needs 1.36 cubic yards at 4 inches and 2.04 cubic yards at 6 inches, with 10% extra.
For a driveway or anything structural, check your local building code or ask a contractor. No manufacturer or code table we can cite gives a thickness for each use, so we don't either.
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How thick should a concrete slab be?
A concrete slab is normally 4 to 6 inches thick, depending on the load it carries (Quikrete). A sidewalk should be at least 4 inches thick. A 10 by 10 foot slab needs 1.36 cubic yards at 4 inches and 2.04 cubic yards at 6 inches, with 10% extra.
For a driveway or anything structural, check your local building code or ask a contractor. No manufacturer or code table we can cite gives a thickness for each use, so we don't either.
Worked examples
The spec's examples, computed by the registry.
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Worked examples
10 x 10 feet patio, 4 inches thick, 10% extra
Length 10 ft·Width 10 ft·Thickness 4 in·Extra for waste and spills 10%
Order 1.36 cubic yards: that is 62 x 80 pound bags or 82 x 60 pound bags.
Concrete to order
1.36 yd³
80 lb bags
62
60 lb bags
82
40 lb bags
123
Cubic meters
1.04 m³
Measured volume (no extra)
33.3 ft³
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Worked examples
10 x 10 feet patio, 4 inches thick, 10% extra
Length 10 ft·Width 10 ft·Thickness 4 in·Extra for waste and spills 10%
Order 1.36 cubic yards: that is 62 x 80 pound bags or 82 x 60 pound bags.
Concrete to order
1.36 yd³
80 lb bags
62
60 lb bags
82
40 lb bags
123
Cubic meters
1.04 m³
Measured volume (no extra)
33.3 ft³
Sources list
Primary sources, then a secondary source (tagged) and the source of a derived figure (listed, not tagged).
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Primary sources
Each calculator uses the standard formula and the manufacturer's own figures, such as bag yields, and rounds up where running short would cost you a trip. Every step is shown. Cost ranges come from named surveys with the date we checked them. Spot something wrong? Tell us and we will fix it and note the change.
Each calculator uses the standard formula and the manufacturer's own figures, such as bag yields, and rounds up where running short would cost you a trip. Every step is shown. Cost ranges come from named surveys with the date we checked them. Spot something wrong? Tell us and we will fix it and note the change.