Outdoor Projects
Create a simple post-grid quantity after a structural plan has established where support lines and allowable spacing belong. The result is a planning check, not a foundation design.
Change the defaults to match your project and the product you plan to buy.
Project result
See the number of post positions along each direction and the resulting simple-grid count plus entered extras.
Planning estimate only. Verify product coverage, package size, supplier specifications and project requirements before purchasing.
Choose the right tool
An approved support layout can be modeled as a simple rectangular grid and you need a post count.
Use Post Hole Concrete after footing/hole dimensions are known; this tool does not design supports or footings.
Methodology
ceil(length ÷ spacing) + 1
Creates end positions and intermediate intervals.
ceil(width ÷ spacing) + 1
Same simple-grid rule in the other direction.
length positions × width positions
Applies only to a full rectangular grid.
grid posts + extras
Adds special supports entered by the user.
Measure only the support grid represented by the structural plan. Many decks do not use posts at every grid intersection; some use beams supported by one row of posts, ledger connections or other layouts. Use this tool only when a rectangular grid is a useful model for the approved project geometry.
Do not use the result to select footing diameter, depth, beam span, post size or spacing. Those are structural and site-specific decisions. Once the design establishes the actual support lines and post locations, use the calculator as a count check and pair each post with the appropriate footing or post-hole concrete estimate.
Reference
| Planning item | Starting point | Verify / adjust |
|---|---|---|
| Grid dimensions | approved support layout | Do not substitute deck footprint automatically. |
| Spacing | design input | Quantity model only. |
| Grid positions | ceil(run ÷ spacing)+1 | Ensures modeled intervals do not exceed input. |
| Footings | separate design | Size/depth not calculated here. |
Questions
No. Many decks use different beam and support layouts. Use this only when the approved design is reasonably represented by the entered grid.
No. Footing dimensions depend on loads, soil, climate and project requirements.
Yes after the project design provides the actual footing or hole dimensions for each post location.
Planning guides
Outdoor Projects
Use an approved support layout to count simple rectangular post positions while keeping footing and structural design separate.
Read guide →Estimate deck joist count and linear footage from deck width, entered joist spacing, joist run length and stock length for purchasing.
Open calculator → Concrete & MasonryEstimate concrete volume and premix bags for cylindrical post holes after subtracting the post volume.
Open calculator → Outdoor ProjectsEstimate decking boards and linear feet from deck dimensions, board width, gap, board length and waste.
Open calculator →