🏗️ FOOTING CALCULATOR
Footing Depth by Project Type
How thick should your concrete slab be? Code-recommended dimensions for any project
| Application | Min Thickness | Recommended | Reinforcement |
|---|---|---|---|
| Sidewalk / Walkway | 3.5" | 4" | Optional fiber |
| Patio | 4" | 4" | Mesh recommended |
| Residential Driveway | 4" | 5" | Mesh or rebar grid |
| Garage Floor | 4" | 5–6" | Rebar grid required |
| RV/Truck Pad | 6" | 6–8" | Heavy rebar grid |
| Shed Foundation (small) | 4" | 4" | Mesh |
| Pool Deck | 4" | 4–5" | Mesh + control joints |
| Hot Tub Pad | 4" | 6" | Rebar grid |
For freeze-thaw climates (Northeast, Midwest, Mountain West), add 1 inch to the recommended thickness. Always check your local building code -- some jurisdictions require 6" minimum for driveways regardless of use.
Footing Pour Checklist
A repeatable order-of-operations that prevents the most common DIY slab mistakes
- Excavate to depth. Slab thickness + base depth + 2" for forms = total dig depth. For a 4" slab on 4" base, dig 10" below final grade.
- Compact subgrade. Native soil should be compacted to 95% before adding base. Don't skip this on clay or recently disturbed soil.
- Lay 4" of crushed stone or roadbase. Compact in 2" lifts. 95% compaction is the target.
- Set forms. 2x4 lumber for 3.5" slabs, 2x6 for 5" slabs. Stake every 4 feet. Check for level and proper slope (¼" per foot away from buildings).
- Place vapor barrier and reinforcement. 6 mil poly under interior slabs. Wire mesh or rebar grid raised 1.5–2" off the base on chairs.
- Pour and screed. Pour from far end working back. Screed level with the forms using a 2x4. Don't over-work the surface.
- Float, edge, and joint. Bull float once water sheen disappears. Edge the perimeter with an edging tool. Cut control joints every 8–10 feet.
- Final finish and cure. Broom finish for traction or trowel for smooth. Cover with plastic for 7 days minimum, lightly mist daily.
- Wait before loading. Foot traffic 24–48 hours. Vehicles 7 days. Heavy equipment 28 days.
Footing Size Quick Reference -- Bags per Footing
Most common residential footing sizes and how many bags each requires
| Footing Type | Dimensions | Cu Ft Each | 80lb Bags Each | Common Use |
|---|---|---|---|---|
| Sonotube 8" × 24" | 8in dia, 24in deep | 0.70 | 2 bags | Light deck posts |
| Sonotube 10" × 36" | 10in dia, 36in deep | 1.64 | 3 bags | Standard deck, pergola |
| Sonotube 12" × 36" | 12in dia, 36in deep | 2.36 | 4 bags | Deck, porch, heavy post |
| Sonotube 16" × 48" | 16in dia, 48in deep | 5.59 | 10 bags | Heavy beam, large deck |
| Pad footing 2×2×12" | 2ft × 2ft × 12in | 4.00 | 7 bags | Column base, post pad |
| Pad footing 3×3×12" | 3ft × 3ft × 12in | 9.00 | 17 bags | Heavy column, support beam |
| Strip footing 16"×8" × 30ft | 16in wide, 8in deep, 30ft | 26.67 | ready-mix | Foundation wall, retaining wall |
Footing Depth by Climate -- Frost Line Guide
Your footing must go below the frost line -- otherwise freeze-thaw cycles will heave it out of the ground
Warm Climates (FL, TX, CA, AZ)
12–18"
No frost depth concern. Code varies -- check local requirement.
Moderate (TN, VA, KY, NC)
18–24"
Light frost. 24" standard for most structural footings.
Cold Climates (MN, WI, NY, MI)
36–60"
Deep frost. Always verify local frost depth before digging.
Step-by-Step: How to Pour a Concrete Footing
The process from digging to curing -- what every DIYer needs to know before they start
- Check your local frost depth. Your footing must go below this depth or freeze-thaw cycles will heave it out of the ground. In Alabama: 6 inches. In Tennessee: 12 inches. In Ohio: 32 inches. In Minnesota: 60 inches. Call your local building department to confirm.
- Call 811 before digging. This is the national "call before you dig" number. Free service. They mark underground utilities within 3 business days. Skipping this step can result in serious injury and large fines.
- Dig to below frost depth plus 6 inches. The extra 6 inches becomes your footing base below the column. Compact the bottom of the hole with a hand tamper or 2×4 before pouring.
- Set your Sonotube form. Cut it to height, check it is plumb and at the correct elevation. Stake the outside if the tube is in a hole wider than the tube diameter. Some contractors use gravel at the bottom for drainage.
- Mix and pour in one continuous operation. Do not stop mid-pour -- it creates a cold joint. For 3–5 bags, use an electric mixer. Wear gloves and eye protection -- wet concrete is caustic and will burn bare skin on contact.
- Set your anchor hardware immediately. J-bolts, post bases, or rebar stubs must be set before the concrete stiffens. Check alignment and position while the concrete is still workable. You have about 30–45 minutes depending on temperature.
Footing Pour: Truck Delivery Guide
Concrete weighs 4,000 lbs per cubic yard. Here is what your truck can legally carry.
| 2026 Truck | Max Payload | Concrete Capacity | Bag Capacity (80lb) |
|---|---|---|---|
| Toyota Tacoma (standard) | 1,521 lbs | ~0.38 cu yd | ~18 bags |
| Toyota Tacoma (i-FORCE MAX) | 1,705 lbs | ~0.42 cu yd | ~21 bags |
| Ford F-150 (PowerBoost Hybrid) | 1,740 lbs | ~0.43 cu yd | ~21 bags |
| Ford F-150 (5.0L V8) | 2,235 lbs | ~0.55 cu yd | ~27 bags |
| Ford F-150 (3.5L EcoBoost) | 2,440 lbs | ~0.61 cu yd | ~30 bags |
| 3/4-ton (F-250, Silverado 2500) | 3,500+ lbs | ~0.87 cu yd | ~43 bags |
*Payload values from 2026 manufacturer specs. Your actual payload is on the door-jamb sticker. Add accessories (toolbox, bedliner) and that number drops 100-300 lbs. A driver and passenger count against payload too.
If your project needs more than 1 cubic yard (4,000 lbs), pickup-truck delivery requires multiple trips. For 2+ cubic yards, ready-mix delivery is almost always cheaper than the gas, time, and suspension wear of multiple bag runs. Most ready-mix trucks deliver 8-10 yards in one trip.
Concrete Footing FAQ
Common questions about calculating and pouring concrete slabs