Driveway Concrete Calculator
Length × width × thickness ÷ 324 to yards, the vehicle thickness ladder, air-entrained PSI, joints and cure-to-park — the driveway-specific law.
Driveway Concrete Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Rectangular pours — elaborate curves bid separately.
- No rebar/mesh tonnage model.
- No subgrade or excavation volume.
In short: 20 ft × 50 ft at 5 in: 1,000 ft² × 5 ÷ 324 = 15.4321 yd³; ×1.10 waste = 16.98 → order 17 yards. At $140/yd delivered: $2,380.00. The ladder says 5 in for SUVs, 6 in with rebar for RVs; 3,500-4,500 psi air-entrained; joints every 10-12 ft; park at 28 days.
Formula
yd³ = ft² × in ÷ 324
order = ⌈net × (1 + waste%)⌉
ladder: 4 in cars / 5 in SUV / 6 in RV+rebar
joints every 10-12 ft; slope 2% away; park at 28 days
[('324', 'ft²·in per cubic yard'), ('4/5/6', 'the vehicle thickness ladder, in inches'), ('air-entrained', 'outdoor concrete, always'), ('28 days', 'full cure — then park')]
Worked Example
- Multiply the two runs; apply ÷ 324.
- Add 5-15% waste; round to whole yards.
- Pick thickness off the vehicle ladder.
- Set PSI for your freeze band; demand air.
- Joints, slope, cure — then park.
20 × 50 at 5 in: 15.4321 yd³ ×1.10 = 16.9753 → 17 ordered, $2,380.00 at $140/yd. Going 5→6 in on this pad adds 3.09 yd³.
Strengths & Limits Of This Model
Where this engine is strong
- The ÷324 law with the order call spelled out
- Vehicle ladder and PSI band as decisions, not prose
- Joint, slope and cure doctrine in one card
Where it stops
- No rebar take-off
- No excavation line
Practical Use Cases
New driveways
Yards and the order call.
RV pads
The 6-in rebar case.
Replacement bids
Checking the contractor's yards.
Widenings
One-bay additions.
Freeze-thaw specs
PSI + air, by region.
Methodology & Editorial Standards
Net yd³ = L × W × in ÷ 324 (the K=324 law), order = ceil(net × (1 + waste%)), cost = order × free-entry $/yd. The thickness ladder and PSI/air guidance are cards, not multipliers. Zero sides, areas past 20,000 ft², thickness outside 2-12 in, waste past 25% refused.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Driveway Concrete Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How much concrete for a 20x50 driveway?
1,000 ft² × 5 in ÷ 324 = 15.43 yd³; at 10% waste order 17 yards — about $2,380 at $140/yd delivered. The ÷324 shortcut is the whole trade.
How thick should a driveway be?
4 in for cars, 5 in for SUVs and pickups, 6 in with rebar for RVs and delivery trucks. Thickness is the cheapest strength you can buy after the pour is gone.
What PSI concrete for a driveway?
3,500 psi minimum; 4,000-4,500 where freeze-thaw cycles live — always air-entrained outdoors. The entrained air gives freezing water room to push without spalling the surface.
How far apart are driveway control joints?
Every 10-12 feet, cutting a quarter of the slab depth. Concrete cracks — joints decide where, which is the difference between a feature and a complaint.
When can you drive on new concrete?
Foot traffic about 7 days, vehicles at 28 days — full cure. The 28-day figure is where the PSI spec is measured; early loads shortcut the strength the mix was bought for.
Should the driveway slope?
2% away from the house — a quarter inch per foot — so storms drain to the street instead of the garage threshold. Flat slabs pond; toward-house slabs flood.
How many 80-lb bags equal a yard of concrete?
A cubic yard is 27 ft³; at 0.60 ft³ a bag that is 45 bags — about 3,600 lb of lifting. Past a yard or two, the ready-mix truck is cheaper than your back.
Driveway page or Slab page?
The Slab page is the generic pad with the buy fork. This page is driveway-specific: the vehicle ladder, air-entrained PSI by freeze band, joints, slope and the 28-day park rule.