Four 16-inch footings
Common early deck footing check.
Increase footing areaFooting checkdeck footing calculator
Deck Footing Calculator
Deck footing size depends on tributary load and soil bearing, but frost depth, uplift, lateral loads, and local code still need project review.
Inputs
Results
Immediate estimateFooting checkIncrease footing area2,094.4 lb capacity vs 2,400 lb estimated load
Deck area192 sq ft
Load per footing2,400 lb
Required diameter17.1 in
Selected diameter16 in
Review the limitations before using this result for planning.
This does not check frost depth, uplift, lateral loads, post bases, pier height, beams, ledgers, or local amendments.
Diagram
Deck footing load
Deck load is distributed across footings and compared with soil-bearing area.
- Tributary area
- Footing diameter
- Soil bearing
How this calculator works
Estimate tributary load per footing and compare it with a round footing area under selected soil-bearing assumptions.
Load model
The calculator distributes deck area evenly across the entered number of footings and multiplies by a selected load assumption.
Soil model
Round footing capacity is estimated from footing area and selected soil bearing. Soil must be confirmed for the site.
Why standalone
Footing size has different search intent than concrete quantity, so it earns a separate canonical page.
Load
deck area x load psf / footing countCapacity
round footing area x soil bearing psfDiameter
sqrt(required area / pi) x 24Assumptions
- Tributary area: Deck area is distributed evenly across the entered footing count.
- Soil: Soil bearing is user-selected and must be confirmed for the site.
Worked examples
Undersized example
Shows an increase-area result.
Increase footing areaFooting checkFAQ
Does this calculate frost depth?
No. Frost depth is local and must be confirmed with the adopted code or building department.
Does it include uplift?
No. Hold-downs, uplift, lateral loads, and post-base hardware are outside this MVP check.
Can I use square footings?
This calculator checks round footings only. Use equivalent bearing area for early comparison.
Sources and review
- 2021 International Residential Code, International Code Council, 2021. Accessed 2026-07-16.
Reviewed 2026-07-16. Planning estimates only; confirm project-specific requirements.