10×18 Concrete Slab (6 inches): Yards, Feet & Bags
This 10 ft x 18 ft slab is perfect for a patio or as a gazebo base. Decide between bags or ready-mix based on your access and waste considerations.
Choose Your Calculator
Slab Calculator
Enter any custom length, width, and thickness to get cubic yards and bag counts.
Open Slab CalculatorBag Calculator
Choose 40/60/80 lb bag sizes and estimate counts for your exact volume.
Open Bag CalculatorWant other sizes? Browse all slab size pages
Quick Answer
Tip: Always confirm the yield printed on your bag label. Bag yield guide
Large pour: consider ready-mix delivery for speed and consistent results. Bag counts this high can take significant mixing time.
Project Notes (Unique)
Round to 0.25 yd³ when ordering and ensure you check yield on the label for accurate delivery quantities.
Ensure the base is well-prepared and consider thickened edges for added strength.
Apply a smooth finish and keep the slab moist during curing for optimal strength.
Thickness Planning for a 10x18 Concrete Slab
A 6-inch slab gives this walkway extra stiffness and tolerance if soil conditions are imperfect or loads may grow over time.
Current spec
This page estimates a 10×18 slab poured at 6 inches.
Load check
Best fit depends on whether this is mainly pedestrian use, storage, or heavier wheel traffic.
Upgrade trigger
If you expect heavier loads later, compare this design against the alternate thickness before ordering.
Before You Pour: 10x18 Base Preparation Steps
Most slab problems start below the concrete. Keep the base level, compacted, and consistent before you pour.
- Strip loose topsoil and organic material until you reach firm subgrade.
- Compact the base in lifts so the 10×18 slab does not settle unevenly.
- Check form height and diagonal measurements before concrete arrives.
- Plan reinforcement, joints, and edge support based on the intended walkway use.
Worked Example for 10×18 at 6 Inches
Step-by-step calculation for this exact slab:
- Convert thickness to feet: 6 ÷ 12 = 0.5000 ft
- Compute area: 10 × 18 = 180 sq ft
- Volume in cubic feet: 180 × 0.5000 = 90.00 ft³
- Convert to cubic yards: 90.00 ÷ 27 = 3.333 yd³
- Add 10% waste buffer: 3.333 × 1.10 = 3.667 yd³
How to Order Concrete for 10×18
This slab needs about 3.33 yd³ of concrete, or 150 80 lb bags before waste. With a waste cushion, plan around 3.67 yd³.
For this volume, ready-mix is usually the safer plan. Round up, confirm delivery minimums, and make sure your crew can place and finish the slab without delays.
Adjust dimensions in the slab calculator or compare bag counts here.
Bag Counts by Waste Buffer for 10×18
Pick a buffer based on site conditions: smooth forms and good subgrade can run leaner; uneven excavation or hard-to-reach pours need more cushion.
| Buffer | Yards (yd³) | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|
| +5% tight pour | 3.50 | 158 | 210 | 315 |
| +10% typical | 3.67 | 166 | 221 | 331 |
| +15% rough subgrade | 3.83 | 173 | 230 | 345 |
What to Expect After Pouring This walkway
For a walkway slab, light foot traffic may come sooner than vehicle loads, but finishing quality still depends on keeping the slab damp and protected early on.
First 24 hours
Protect edges, prevent washout, and avoid unnecessary traffic while the slab sets.
Days 2-7
Maintain curing conditions and monitor joints, surface drying, and weather exposure.
Up to 28 days
Concrete keeps gaining strength, so wait for the right service window before heavy use.
How to Estimate This Slab in 3 Steps
Measure
Length 10 ft, width 18 ft, thickness 6 in.
Compute Volume
Area: 180 sq ft → volume: 90.0 ft³ → 3.33 yd³.
Add Waste
Add a small buffer for spillage and uneven subgrade, then round up when ordering.
Planning Notes
Common uses: patio, gazebo base, walkway section.
For more context and conversions, see the Concrete Calculator hub.
Frequently Asked Questions
What should I consider when choosing between bags and ready-mix concrete?
Consider your project size, access to the site, and whether you prefer the convenience of ready-mix or the flexibility of bags.
How do I prepare the base for my concrete slab?
Ensure the base is level, compacted, and free of debris to provide a solid foundation for the slab.
What thickness should I choose for my concrete slab?
A thickness of six inches is generally suitable for patios and walkways, but consider the load it will bear.
How can I minimize waste when ordering concrete?
Always plan for a little extra to account for spillage or miscalculations, and round your order up accordingly.
Related Slab Sizes
Ready to Calculate Your Project?
Get instant estimates for cubic yards, cubic feet, and bag counts. No signup required.