Six-foot spacing target
Simple deck beam post layout.
4 postsEstimated deck postsdeck post spacing calculator
Deck Post Spacing Calculator
Deck post spacing starts as a layout problem, but the final spacing must work with the beam, footing, soil, bracing, and local code.
Inputs
Results
Immediate estimateEstimated deck posts4 posts4.67 ft between posts along the beam
Beam layout length14 ft
Beam bays3
End inset1 ft
Estimated load per interior post1,400 lb
Review the limitations before using this post layout for planning.
Post spacing depends on beam size, post size, footing capacity, lateral bracing, guard loads, ledger details, soil, frost, and local code.
Diagram
Deck post layout
Beam length and target spacing are converted into bays, posts, and actual spacing.
- Beam length
- Post bays
- Deck load
How this calculator works
Enter beam length, target maximum spacing, end inset, and deck projection to plan a simple deck post layout.
Layout model
The engine subtracts end insets from the beam length, divides the remaining length by the target maximum spacing, and rounds up to whole bays.
Load model
A simple tributary load estimate multiplies actual post spacing by half the deck projection and a selected load assumption.
Structural caution
This plans spacing only. Beam span, footing size, post height, lateral bracing, ledgers, guards, and uplift still need project review.
Usable beam length
beam length - two end insetsBay count
usable length / maximum post spacing, rounded upPost load
actual spacing x half deck projection x design loadAssumptions
- Layout: Posts are evenly spaced between the two entered end insets.
- Load: Load per post is a simple tributary estimate for early planning.
Worked examples
Longer beam
Adds bays to stay below the target spacing.
5 postsEstimated deck postsFAQ
Can I just space deck posts every 6 feet?
Six feet is a common planning target, but the allowable spacing depends on beam size, load, footing capacity, and local requirements.
Does this size the beam?
No. Use a deck beam table, code guide, or qualified designer to verify the beam.
Does this include footings?
It estimates a simple load per post. Use the deck footing calculator for a separate simplified footing check.
Sources and review
- 2021 International Residential Code, International Code Council, 2021. Accessed 2026-07-16.
Reviewed 2026-07-20. Planning estimates only; confirm project-specific requirements.