How much concrete do I need?
Cubic yards and bags for slabs, footings, post holes, and stairs. Free, no email required to see the math.
Your inputs
4" is typical for a patio or shed pad; 5–6" for a driveway.
You'll need
Assumptions (tap to adjust)+
The math, in plain English.
Concrete is sold by the cubic yard (27 cubic feet), so every shape here gets reduced to cubic feet first: a slab is length × width × thickness, a footing is the same with depth, a post hole is a cylinder, and stairs are a stack of blocks that each get one step taller. Then we add waste — the ground is never perfectly flat, forms bow, and some always ends up on the wheelbarrow — and convert to yards and bags.
The bags-vs-truck line is about a yard. Under that, bagged mix from the yard is fine and you skip the short-load fee. Over it, you are mixing 60-plus bags by hand and a ready-mix truck is cheaper and gives you one consistent batch. For deck posts, a few bags per hole is normal; for a patio slab, call the plant.
Two things the calculator can't see: what's under the pour and what the county wants. A slab needs compacted gravel and a vapor barrier under it, and structural footings have depth and rebar requirements tied to code. If it's holding up a deck or an addition, get the footing spec from the permit office before you dig.
Concrete questions
How deep do footings need to be in Clark County?+
Footings are commonly required to sit on undisturbed soil below the frost line — locally you will hear anything from 12" to 36" depending on the structure and the soil. Confirm the number with the Clark County or City of Vancouver permit office before you dig; it changes with what the footing is holding up.
Bags or a ready-mix truck?+
Under about a yard, bags. An 80 lb bag yields 0.6 cu ft, so a yard is 45 of them — that is a long afternoon with a mixer. Past a yard, a truck is cheaper per yard, arrives mixed to spec, and you are not racing a setting batch.
Do I need rebar or wire mesh?+
For a walkway or shed pad, fiber mix or wire mesh is usually enough. Driveways, footings, retaining walls, and anything a structure sits on typically call for rebar on a set spacing. The permit drawings will spell it out for structural pours.
How long does concrete take to cure?+
You can walk on it in 24–48 hours, park on it in about a week, and it reaches design strength at 28 days. Keep it damp for the first few days in dry weather, and do not pour if a hard freeze is coming — Clark County winters can do that.
Do I need a permit for a concrete slab in Vancouver, WA?+
Plain flatwork like a walkway, patio, or small shed pad is commonly exempt, while footings for a deck, addition, or any structure need a permit — confirm with the permit office before you pour. If the slab drains toward the house or touches the property line, ask about that too.
What does a concrete pour cost in Vancouver, WA?+
These ranges reflect the Vancouver, WA / Portland metro market — outside the area, treat them as a rough guide. A typical range for a simple slab runs several dollars per square foot for the concrete alone and more with excavation, gravel base, forms, and finish. Want a real number? Request a free estimate and we price the prep, the pour, and the finish line by line.
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