Deck Stairs & Railing Calculators
Two calculations with the least tolerance on the whole deck. Stair risers have to be equal within a fraction of an inch, and baluster gaps have a hard code ceiling. Both are worth getting right on paper first.
These two calculations have the least tolerance on the whole deck, and they fail inspection more often than anything structural.
Stair risers have to be equal — not roughly equal. The limit is on the difference between the tallest and the shortest riser in the entire flight, which is why the bottom step is where flights go wrong: the landing is almost never exactly where the drawing said it would be.
Baluster spacing has a hard ceiling, and it is a child-safety rule rather than a styling one. The gap is not measured between balusters in the abstract — it is whether a sphere will pass through any opening in the guard, anywhere, including the triangle where the stair meets the bottom rail.
Both are worth resolving on paper before you cut anything.