How many balusters for a 6 ft railing section?
A 6 ft railing section (68½ inches between 4×4 posts) takes 13 balusters of 1½ inch 2×2 stock, spaced an even 3-1/2 inches apart — 5 inches on center, with the first baluster center 4-1/4 inches from the post.
How to work it out
- (68-1/2 in − 3-3/4 in) ÷ (1-1/2 in + 3-3/4 in) = 12.33 → round up to 13 balusters
- (68-1/2 in − 13 × 1-1/2 in) ÷ 14 gaps = 3-1/2 in (3.5 in)
Six-foot post spacing with 4×4s is the classic deck railing layout, and it happens to divide perfectly: thirteen 2×2s leave fourteen gaps of exactly 3½ in. Rip one spacer block at 3½ in and the whole section goes up without a tape.
Measure between your actual posts first — a post set ¼ in out of line changes the gap on that section, and it is easier to rerun the numbers than to fudge the last gap.
Adjust for your project
More options: Layout
- Exact gap (decimal)
- 3.5 in
- Middle of the section
- A baluster, centered
- Balusters for all sections
- 13 balusters
- Center-to-center spacing
- 5 in
- Post face to first baluster center
- 4-1/4 in
- Screws (2 top, 2 bottom each)
- 52 screws
- Balusters and 2×2s are not perfectly uniform. Measure a few, and cut a spacer block to the exact gap instead of measuring each one.
Balusters for a 6 ft section, by baluster width
| Baluster width | Balusters per section | Exact gap (decimal) | Center-to-center spacing |
|---|---|---|---|
| 0.75 in | 15 balusters | 3.58 in | 4-5/16 in |
| 1 in | 14 balusters | 3.63 in | 4-5/8 in |
| 1.25 in | 13 balusters | 3.73 in | 5 in |
| 1.5 in | 13 balusters | 3.5 in | 5 in |
What to know about a 6 ft railing section
The 3½ in gap clears the rule in IRC R312.1.3 that a 4 in sphere must not pass through any opening in a guard, with ½ in to spare for boards that shrink or bow. That margin matters with pressure-treated 2×2s bought wet, which can narrow as they dry. A guard is required where the deck surface is more than 30 in above the grade within 36 in of its edge (R312.1.1), and its top must be at least 36 in above the deck (R312.1.2).
With an exact 3½ in gap there is no rounding to spread around: set the spacer against the post, fasten a baluster, move the spacer, repeat. Check plumb with a level every three or four balusters. Across thirteen pieces, a small lean adds up faster than any gap error, and you will see it from the yard.
For a whole deck, count sections rather than feet. Six 6 ft sections take 78 balusters and 312 screws at two per end, before any spares for split or badly bowed pieces. The screws are close to the ends of each 2×2, so pre-drill.
Longer post spacing is on How many balusters for an 8 ft railing section. If the railing continues down the stair, the open side of a stair allows a 4-3/8 in sphere instead; How many steps for a 4 ft deck is the height at which the stair needs that guard.
Different size? Use the full Baluster Spacing Calculator.
What you’ll need
- Cordless drill/driver kitMid-range price
Drills pilot holes and drives screws for decks, fences and furniture. An impact driver is a worthwhile add-on for long deck screws.
See options on Amazon (opens in a new tab) - Exterior deck screwsBudget price
Coated or stainless screws rated for treated lumber. Match the screw to your decking — composites often need their own.
See options on Amazon (opens in a new tab) - 25 ft tape measureBudget price
A 25 ft tape with a stiff blade and a readable 1/16 in scale covers everything from cut lists to deck layout.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many 2×2 balusters for six 6 ft railing sections?
78 balusters in all — 13 balusters per section — and 312 screws at two per end.
How many balusters for a 6 ft stair railing section?
With 7½ inch steps and a 10½ inch run the rail slopes about 35.5°, so 68½ inches measured along the rail is only 55-3/4 in (4 ft 7-3/4 in) level. That takes 10 balusters of 1½ inch stock with gaps a hair over 3-11/16 in, marked 6-3/8 in apart along the rail.
How many ¾ in metal balusters for a 6 ft railing section?
15 balusters, with gaps of a hair over 3-9/16 inches (3.58 in) and 4-5/16 in on center. Follow the maker’s spacing if the rails come pre-drilled.
Other common sizes
- How many balusters for an 8 ft railing section — 17 balusters
Sources
- International Code Council, 2021 International Residential Code, Chapter 3 Building Planning (opens in a new tab) — R312.1.1 when a guard is required; R312.1.2 guard height (36 in; 34 in on the open sides of stairs); R312.1.3 openings: a 4 in sphere must not pass, except 4-3/8 in for guards on the open side of stairs and 6 in for the triangle formed by the riser, tread and bottom rail.