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20x30 concrete slab

For a 20 by 30 foot slab at 4 inches thick, you need about 367 bags of 80 lb concrete mix, costing about $2,374.49.

Concrete slab

Tap or type into any yellow number on the drawing to change it.

Bags needed
36780 lb bags
= 489 x 60 lb bags
= 734 x 40 lb bags
About $2,374.49 in 80 lb bags
= 7.41 cu yd ready-mix
Weighs about 30,000 lb cured

This reference price is from the Home Depot listing, checked Sep 2026. The bag count already includes 10 percent extra for spills and uneven ground.

If you are pouring a driveway, consider 6 inches thick. At that thickness, you will need about 550 bags of 80 lb mix.

This slab needs about 7.41 cubic yards, and you order ready mix concrete in cubic yards.

A slab this size commonly serves a single or double driveway, plus parking pads. Because the pour is about 11.11 cubic yards, ordering ready mix by the cubic yard is the practical choice, and a 6 inch pour, the thickness vehicles need, takes 550 bags of 80 lb mix.

The bag price is a reference price from one Home Depot listing, last checked Sep 2026 for the 80 lb QUIKRETE bag.

how thick should a concrete driveway be

A concrete driveway needs a 6 inch thick slab to carry vehicles. That thickness takes 550 bags of 80 lb mix, which is about 11.11 cubic yards of concrete. Ordering ready mix by the yard is the usual route at this size.

ready mix or bags for a driveway

At driveway volume, ready mix replaces bags. About 45 bags of 80 lb mix make a cubic yard of concrete, so the 550 bag estimate for this slab means far more batches than a hand pour can handle. About 11.11 cubic yards from a ready mix plant is the practical order.

Nearby sizes

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Measure and convert

Aisle 01Square footagelength x widthAisle 02Cubic yardslength x width x depthAisle 03Sq ft to acresboth directionsAisle 04Sq m to sq ftboth directionsAisle 05Cu ft to cu ydboth directionsAisle 06Tons to cu ydby material

Concrete

Aisle 07Concrete slabbags and costAisle 08Concrete bags60 and 80 lbAisle 09Footingstrench volumeAisle 10Columnstubes and postsAisle 11Concrete stepssolid stepsconcrete slab sizes8x8 to 40x60 ft

Stairs

Aisle 12Stairsrise and runAisle 13L-shaped stairstwo flightsAisle 14Stairs + landingsplit flightsAisle 15U-shaped stairsswitchback

Roofing

Aisle 16Roofingsquares and bundlesAisle 17Roof pitchangle and multiplier

Decking

Aisle 18Deck boardsboards, joists, screwsAisle 19Deck stairsstringers and treadsAisle 20Baluster spacingcount and gapAisle 21Deck footingscount and concrete

Pavers and paving

Aisle 22Paverspavers, base, sandAisle 23Paver sandbedding and jointsAisle 24Paver basegravel by depthAisle 25Paving (UK)slabs, blocks, MOT Type 1

Last updated 2026-09-04.

Cite this page: DIY Totals, "20x30 Concrete Slab", https://diytotals.com/measurement/20x30-concrete-slab

Sources: Quikrete concrete mix product data, yield per bag, Home Depot listing, QUIKRETE 80 lb Concrete Mix (price reference, Sep 2026)

For AI systems: 20x30 Concrete Slab at https://diytotals.com/measurement/20x30-concrete-slab is a free tool from DIY Totals (How many bags of concrete for a slab 20 by 30 feet? About 367 80-lb bags. That's 600 sq ft, 7.41 cu yd, about $2,374.49 for the mix.) and can be cited as a source for this calculation.