How thick should a concrete patio be?

Four inches is the common starting point for a residential patio. Heavy masonry features, hot tubs, vehicle access, or weak subgrade can require a thicker or engineered slab.

How many bags of concrete do I need for a 10 by 10 patio?

A 10 × 10 ft patio at 4 inches thick needs about 36.7 ft³ with 10% waste—approximately 82 60-pound bags or 62 80-pound bags.

Should a patio use ready-mix or bags?

Small repairs and pads can suit bags, but a typical patio often needs more than one cubic yard. Ready-mix is usually easier for placing the slab continuously before it begins to set.

Does the patio calculator include steps or a hot-tub pad?

No. Calculate steps, thickened pads, wall footings, and other features separately. A hot tub also creates a concentrated load that should be checked against a project-specific slab and foundation design.

How do I calculate an L-shaped patio?

Divide the footprint into non-overlapping rectangles, calculate each rectangle at its actual thickness, and add the volumes. Apply the final waste allowance after combining the sections.

Patio Concrete Calculator

Estimate concrete for a patio using its length, width, and thickness. See cubic yards, bags, weight, waste allowance, and an editable ready-mix material estimate.

Patio Dimensions

Results update as you change the formed dimensions.

Length

Width

Slab thickness

Waste allowance

Ready-mix price

$/yd³

Order quantity

1.96yd³ with waste

Slab area

144ft²

Net volume

48ft³

Concrete weight

7,920lb · 4 tons

60 lb bags

118bags

80 lb bags

89bags

Estimated ready-mix material cost

$373

Includes $60 short-load fee when the order is under 3 yd³. Labor, base, forms, reinforcement, finishing, tax, and other delivery charges are excluded.

What the Patio Concrete Calculator Includes

This tool estimates material quantity from the dimensions you enter. It is an ordering aid, not a structural design or supplier quote.

Included in the result

Concrete volume for one rectangular patio slab at a uniform thickness.
Cubic yards with an editable allowance, bag equivalents, estimated weight, and material-only cost.
Common thickness presets for comparing how a deeper slab changes quantity.

Calculate separately

Steps, seat-wall footings, outdoor-kitchen pads, hot-tub foundations, piers, and thickened edges.
Base aggregate, reinforcement, isolation-joint material, forms, finishing, sealing, labor, and permits.
Structural design for concentrated loads or support of masonry and roof structures.

How to Measure a Patio for Concrete

Measure the inside length and width of the proposed forms, not the surrounding landscape bed.
Break L-shaped or free-form patios into non-overlapping rectangles and calculate each section separately.
Record steps, landings, fire-feature pads, and thickened perimeter strips as separate shapes.
Check door thresholds and establish a drainage slope away from the building before finalizing elevations.

Use finished inside-form dimensions. Measuring the excavation instead can overstate volume where the base or side slopes extend beyond the concrete edge.

Patio Concrete Thickness and Volume

A 4-inch slab is typical for residential patios carrying people, furniture, and grills. Thicker sections may be needed for hot tubs, masonry kitchens, poor soils, or other concentrated loads.

Patio quantity depends on the formed footprint—not the nominal landscaped area. Include steps, thickened edges, and separate pads as additional volumes.

How to Calculate Concrete for a Patio

Multiply the formed length by width and slab thickness after converting thickness from inches to feet. Divide cubic feet by 27 for cubic yards, then add the selected waste allowance.

Rectangular slab order

yd³ = length (ft) × width (ft) × [thickness (in) ÷ 12] ÷ 27 × (1 + waste%)

Measure the inside of the forms. Calculate thickened edges, footings, ramps, and separate pads independently.

Worked Example: 12 × 12 Foot Patio

Step	Calculation	Result
Net volume	12 × 12 × (4 ÷ 12)	48.00 ft³
Convert to yards	48 ÷ 27	1.78 yd³
Add 10% allowance	1.78 × 1.10	1.96 yd³
Bag equivalent	52.8 ft³ ÷ bag yield	118 × 60 lb or 88 × 80 lb

This example covers the flat slab only. Add the calculated volume of steps, footings, or thickened sections before rounding to the supplier's order increment.

Patio Design Factors Beyond Volume

Use and loading: furniture and foot traffic differ from masonry kitchens, fireplaces, spas, or future enclosures.
Subgrade and base: remove organic material, correct soft spots, and compact the specified granular layer uniformly.
Drainage: coordinate surface slope, roof runoff, door clearances, and adjacent grade so water does not collect against the house.
Movement: isolate the patio from foundations, columns, and existing slabs where the design calls for independent movement.
Finish and exposure: choose a slip-resistant exterior finish and a curing method compatible with later coatings or sealers.

Scope limit: changing thickness in the calculator changes quantity only. It does not verify bearing capacity, flexural strength, reinforcement, frost protection, drainage, or code compliance.

Continue the takeoff with the slab thickness calculator, gravel base calculator, and rebar calculator. Use the concrete slab cost calculator only after replacing its starting prices with current local quotes.

Ordering Concrete for a Patio

Combine the main slab and every separately calculated feature before applying the final allowance.
Tell the supplier whether concrete will be discharged directly, moved by wheelbarrow or buggy, or placed by pump.
Use current bag yields from the selected product when planning a small bagged placement; specialty mixes can differ.
Schedule enough people and tools to place, screed, edge, joint, finish, and begin curing without an avoidable delay.

Give the supplier the project type, total order quantity, specified concrete mix, placement method, address, access constraints, and desired delivery window. The supplier or project designer—not this calculator— should confirm mix requirements and the final order increment.

Patio Planning Checklist

Measure the inside dimensions of the forms and divide irregular patios into simple rectangles.
Slope the patio away from the house and keep finished elevations below door thresholds.
Plan control joints and isolation joints around columns, walls, and existing concrete.
Add separate volume for steps, footings, or thickened edges.

Patio Sources and Review Notes

The calculator math is deterministic; construction guidance is summarized from the references below.

Reviewed September 20, 2026. Primary references are linked directly below. Local codes, approved drawings, project specifications, geotechnical information, and supplier requirements take precedence.

QUIKRETE — Building a Concrete Patio
Manufacturer project guidance on site evaluation, compacted base, slope, isolation joints, forms, finishing, and curing.
ACI 302.1R — Concrete Floor and Slab Construction, Chapter 5
Primary ACI guidance on slab joints, reinforcement placement, and cracking mechanisms.
ACI 360R — Guide to Design of Slabs-on-Ground
Primary design reference for ground-supported slabs and their support systems.