Estimating Concrete Jobs from First Principles
Concrete flatwork — driveways, patios, sidewalks, garage floors — is a high-ticket residential and commercial service with straightforward materials math once you understand the process. This guide walks through how to calculate material quantity, price labor, and build a complete estimate that protects your margin.
Calculating Cubic Yards
Concrete is ordered and priced by the cubic yard. To calculate the volume you need:
Formula: Length (ft) × Width (ft) × Depth (inches) ÷ 12 ÷ 27 = cubic yards
Example: 20 ft × 40 ft driveway, 4 inches thick = 20 × 40 × 4 ÷ 12 ÷ 27 = 9.88 yards → order 10.5 yards (add 5–10% overage)
| Application | Standard Thickness | PSI Recommendation | Notes |
|---|---|---|---|
| Residential driveway | 4 inches | 3,000–4,000 PSI | Reinforce with wire mesh or rebar |
| Patio / walkway | 3.5–4 inches | 3,000 PSI | Fiber reinforcement common |
| Garage floor | 4–6 inches | 3,500–4,000 PSI | Consider vapor barrier |
| Commercial driveway/lot | 5–6 inches | 4,000–5,000 PSI | Rebar grid required |
| Retaining wall | 8–12 inches | 4,000+ PSI | Engineered design often required |
Material Cost Breakdown
- Ready-mix concrete delivery: $150–$220 per cubic yard depending on mix design and market
- Short load charge: Expect $100–$300 surcharge for orders under ~5–7 yards
- Rebar (grade 40 or 60): $0.50–$0.85/linear foot; estimate from your grid layout
- Wire mesh (6×6 WWF): $0.15–$0.25/sq ft
- Fiber reinforcement (added to mix): ~$15–$25 per yard upcharge from supplier
- Form lumber (2×4 or 2×6): $0.60–$1.00/linear foot of perimeter
- Gravel base (4-inch compacted): $0.50–$1.00/sq ft installed
- Sealer (concrete cure/seal): $0.10–$0.30/sq ft depending on product
Labor Pricing
Labor for concrete flatwork is typically priced per square foot for the complete process: form set, pour, finish, and strip forms. Standard market rates:
- Broom finish flatwork: $5–$9/sq ft labor
- Exposed aggregate: $8–$14/sq ft labor
- Stamped concrete: $12–$20/sq ft labor (pattern + color add complexity)
- Decorative saw cuts: $1–$2/linear foot add-on
- Demo and removal of existing concrete: $2–$5/sq ft depending on slab thickness and disposal
Full Estimate Example
Example: 600 sq ft driveway replacement (broom finish)
- Demo existing concrete: 600 sq ft × $3 = $1,800
- Gravel base regrade: 600 sq ft × $0.75 = $450
- Concrete (10.5 yards × $180): $1,890
- Rebar and wire mesh: $280
- Forms and miscellaneous: $150
- Labor (600 sq ft × $7): $4,200
- Total: ~$8,770
Build your concrete estimates in Fieldbase with pre-loaded material unit costs. Update your concrete delivery price each season as ready-mix prices change and every estimate reflects the current cost automatically.
Key Takeaways
- Calculate cubic yards precisely — add 5–10% overage and check for short-load surcharges
- Price demo, gravel base, reinforcement, and sealing as separate line items
- Stamped and exposed aggregate finishes cost 2–3× broom finish in labor — price accordingly
- Include concrete cost validity period (30 days) since ready-mix prices fluctuate seasonally