Deck Footing Calculator
Enter your deck size and frost zone to get the number of footings, posts, concrete bags, and total cost.
Last updated: June 2026
Most of the US — frost line at 36 inches
Footing & Material Estimate
Price data sources: HomeAdvisor 2026 Deck Cost · AWC Wood Frame Construction Manual · IRC Deck Construction Guide
Last verified: June 2026
Footing depth requirements vary by local building code. Always check with your building department.
Frost Depth Requirements by Region
| Frost Zone | Footing Depth | Applies to |
|---|---|---|
| Shallow | 24" | Southern climates without ground freeze |
| Standard | 36" | Most of the US — frost line at 36 inches |
| Deep | 48" | Northern climates with deep frost line |
Cost Breakdown (per footing)
| Component | % of Cost | What it covers |
|---|---|---|
| Concrete (bagged) | 30-35% | 80 lb bags of concrete mix, ~$5/bag |
| Sonotubes (cardboard forms) | 15-20% | 12-inch diameter tubes, $15-$25 each |
| Post anchors/hardware | 20-25% | Galvanized post bases, anchors, ABU-style brackets |
| Labor (digging + pouring) | 25-35% | Post hole digging, tube setting, concrete mixing, curing |
How Location Affects Your Cost
| Region | Labor | Materials |
|---|---|---|
| Midwest | 1x | 1x |
| Southeast | 0.9x | 0.95x |
| Southwest | 1.05x | 1.1x |
| Northeast | 1.3x | 1.2x |
| West Coast | 1.4x | 1.25x |
To adjust: multiply the calculator's total by your region's average multiplier. Source: Remodeling Magazine 2026 Cost vs Value Report regional indexing + HomeAdvisor 2026 Regional Cost Index.
Deck contractor? Price footings and full builds.
JobTread handles deck material takeoffs (footings, joists, decking boards, railing) and generates complete project bids with payment schedules.
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Try JobTread FreeRed Flags in Contractor Quotes
We've reviewed hundreds of quotes. These are the warning signs that a contractor may cut corners or overcharge:
- Footings above frost line: Must go below local frost depth. Going shallow guarantees heaving.
- Using deck blocks for attached deck: Building code requires proper concrete footings for attached decks.
- No permit pulled: Most decks over 30 inches high need permits and inspection.
- Skipping pre-pour inspection: Most codes require footing inspection BEFORE concrete is poured.
Common Deck Footing Mistakes
Too shallow: The #1 cause of deck failure. Footings must go below frost line. Even one season of freeze-thaw will heave a shallow footing and crack the deck frame.
Wrong diameter: 12-inch diameter is standard for residential decks. Going to 8 inches saves $20/footing but reduces load capacity by 50%. Not worth it.
No sonotube: Pouring concrete directly into the hole without a sonotube creates an irregular shape that's weaker and harder to attach post anchors to.
Skipping inspection: Most codes require footing inspection BEFORE concrete pour. Pouring without inspection means you may have to dig it up and redo.
Frequently Asked Questions
How deep should deck footings be?
Deck footings must extend below the local frost line to prevent heaving. In most of the US, that's 36 inches deep. In southern states (FL, TX, AZ), 24 inches is sufficient. Northern states (MN, ME, ND) may require 48-60 inches. Check your local building code for the exact frost depth. The footing diameter is typically 12 inches for residential decks. Going too shallow causes the deck to heave and crack during freeze-thaw cycles.
How many footings do I need for my deck?
Most decks need footings spaced every 6-8 feet along each beam. A typical 12x16 deck (192 sq ft) with 2 beams needs 6-8 footings total. Calculate: beam length ÷ 8 feet + 1 = footings per beam. Multiply by number of beams. For a 200 sq ft deck with 2 beams of ~14 feet, that's (14÷8+1)×2 = 6 footings. The calculator above does this automatically. Always add one extra footing for safety on multi-level decks.
Do I need a permit for deck footings?
Yes, in almost all jurisdictions. Most building codes require permits for decks over 30 inches high or over 200 sq ft. The permit process includes footing inspection (before concrete pour) and final inspection. Inspection costs $50-$200 and is required for insurance and resale. Unpermitted decks must be retroactively permitted or removed during home sale — always pull permits.
Can I use deck blocks instead of concrete footings?
Deck blocks (precast concrete blocks that sit on the ground) work for low, freestanding decks under 30 inches high in non-frost climates. They're cheaper ($10-$15 each vs $100+ for poured footings) and faster to install. But they don't meet code for attached decks, decks over 30 inches, or any deck in frost-prone areas. Most jurisdictions ban deck blocks for anything beyond a small garden platform. For permanent decks, always pour proper footings.
How much concrete do I need for one deck footing?
A standard 12-inch diameter footing at 36 inches deep requires about 2.8 cubic feet of concrete — roughly 3 bags of 80 lb concrete mix ($15). At 48 inches deep, that's about 4 bags ($20). Buy 10% extra for waste. For multiple footings, bulk concrete delivery (1+ cubic yards at $120-$150/yard) is cheaper than buying individual bags. A typical 6-footing deck needs about 17 cubic feet — under the 1-yard minimum, so bagged is the practical choice.
Can helical piers replace concrete deck footings?
Yes — helical piers (steel shafts with screw-like helices twisted into the ground) are a code-approved alternative to concrete footings in most jurisdictions. They cost $150-$250 each installed vs $100-$150 for a poured concrete footing, but install in 30 minutes each with no digging, no concrete cure time, and no excavation mess. Load capacity is typically 5-10 tons per pier (vs 2-3 tons for standard concrete footings). Best use cases: wet soils where concrete won't cure, tight access (no room for excavation equipment), and decks built over existing landscaping. Drawback: requires specialized installer — not a DIY option.
How to dig deck footing holes without an auger?
Use a manual post hole digger (clamshell type, $40-$80 at hardware stores). For a 12-inch diameter × 36-inch deep hole in average soil, expect 30-60 minutes per hole with two people trading off. Rocky soil doubles the time. Alternative tools: digging bar ($40) for breaking up hardpan, mattock ($35) for root cutting, post hole digger with handles extended for deeper holes. Avoid shovel-only digging — holes end up too wide (wasting concrete). Gas auger rental ($75-$120/day) makes sense for 5+ holes. Call 811 (utility locator) at least 48 hours before digging — it's free and legally required.
Real Project Example
12x16 ft Deck — 6 Footings at 36 in Depth
Portland, OR · 2026
Built a ground-level composite deck on a sloped backyard, requiring deep footings to clear the local frost line.
How It Went Down
Layout and digging
Marked footing locations with batter boards, dug 6 holes at 12 in diameter
Went 36 in deep — 18 in below frost line — to anchor a freestanding deck. Used a two-man gas auger, dug in 40 min
Concrete and post bases
Poured quikrete to grade, set galvanized post bases on J-bolts
J-bolts set wet then re-checked with string line once concrete cured 24 hr — one was off 1/2 in, easy fix with a washer
Beam and posts
4x4 treated posts on post bases, 4x10 beam through-bolted
Used hot-dip galvanized through-bolts, not lag screws — lag screws pull out over time on treated lumber
Inspection
Passed county inspection before framing continued
Inspector verified footing depth with a tape measure — flagged a neighbor for stopping 6 in short of frost depth
What we learned: Digging 18 in past the frost line costs $40 extra in concrete but prevents heave. We saw the deck next door lift 2 inches in one winter because the footings stopped at the frost line instead of going below it.
EstimatorSuite contractor interviews, 2026
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