Even Spacing Calculator
Exact on-center spacing for posts, balusters, shelving, and pickets — calculated instantly
Download Free on Google Play
Exact on-center spacing for posts, balusters, shelving, and pickets — calculated instantly
Download Free on Google PlayEnter your run and get exact on-center spacing, a full mark-out list, and a live layout diagram — no install, right here in your browser.
Working on the jobsite? Get the free Android app — it works offline, saves your calculation history, and a one-time Pro unlock exports a print-ready PDF cut sheet you can print for the shop or text to the crew.
The Even Spacing Calculator is the ultimate tool for woodworkers, DIY enthusiasts, and construction professionals who need perfectly distributed layouts in seconds. Whether you're installing railing balusters, fence pickets, deck planks, bookshelves, or wall art, this app handles the complex math so you can focus on building.
Any time you need a row of things spread out so the gaps all match, the same on-center math applies. A few of the layouts people reach for it:
Deck balusters and railing spindles, fence pickets and posts, wall studs on-center, shelf brackets and shelf pins, cabinet knobs and drawer pulls, and slats for screens or a headboard.
A row of picture frames or wall art, coat hooks and wall hooks, curtain rings, tile and backsplash layouts, and evenly spaced holes for a pegboard or grid.
Tree and plant spacing down a row, garden bed markers, deck-post and pier layouts, and fence-line stakes — anywhere you need even center-to-center distances across a run.
Whatever you're laying out, enter the total run, how many pieces, and their width — the calculator returns the exact on-center spacing and clear gap, to 1/64" or the whole millimetre.
If you want to do it by hand, here's the whole thing. To space n pieces evenly across a length L, where each piece is w wide and a piece sits at each end of the run:
That gives you the distance from the center of one piece to the center of the next. The clear gap between pieces is simply:
The reason you measure on-center rather than gap-to-gap: mark every center from one end with a tape, and a rounding error can't accumulate. Measure each gap in turn and the errors stack — by the seventh picket you're visibly out.
A deck rail with 96" between posts, 8 balusters, each 1.5" wide:
A fence panel 2000 mm wide, 6 pickets, each 50 mm wide:
Real numbers rarely land that clean. Divide 2400 mm by 7 and you get 342.857… — and that's the point where the scrap paper starts. The app does this division for you, rounds every position to something you can actually mark (a whole millimetre, or a fraction down to 1/64"), and lists every center from one end so nothing drifts. It also handles edge offsets when the run doesn't start flush, and shows the layout as a diagram before you cut.
Customize accuracy up to 1/64" for meticulous detail work. Perfect for fine woodworking where every fraction matters.
Now supports both Imperial (inches) and Metric (mm) measurements. Work in whatever system you prefer.
Get the exact center-point for every piece, ensuring perfect alignment for posts, balusters, and more.
Toggleable view that lists the "start" and "center" positions for every single piece—perfect for long runs like fences or decks.
NEW: Set inset spacing from edges for professional-looking layouts with proper margins.
NEW: Calculate exact spacing including the width or thickness of your materials for gap-accurate layouts.
Save and share your measurements with your team or for future reference. No more losing your calculations.
Export a print-ready vector PDF: your full mark-out list, on-center and clear-gap dimensions, and a scale bar so it reads true on paper at whatever size you print. Print it for the shop or text it to the crew. A one-time purchase — no subscription — and it also removes the banner ad.
A diagram draws your spacing as you type, so you can see the run before you cut anything. Catch the mistake on the screen instead of on the lumber.
Every calculation is saved. Come back to the job tomorrow, or hit the next identical run, and pull the numbers straight back up — no re-entering.
The full calculator — every number, the measurement table, the live diagram, history, and sharing your figures — is free, supported by a single banner ad. No subscription, ever.
Free (ad-supported): the entire calculator — on-center & clear-gap numbers, the measurement table, live diagram, calculation history, and sharing your figures. Everything you need to lay out a run.
Pro — one-time unlock: export the print-ready PDF cut sheet, and remove the banner ad. Pay once. Never a subscription.
Balusters, spindles, shelving, shelf brackets, cabinet hardware, and trim work. Get professional results every time.
Timber screws, fasteners and joists at equal centers. Work out your fixing pattern in millimetres or inches before the first screw goes in.
Fence posts, fence pickets, deck boards, siding, framing studs, and structural layouts. Build with confidence.
Picture frames, wall hooks, gallery walls, floating shelves, and lighting fixtures. Achieve that designer look.
Deck railings, fence pickets, pergola beams, and garden borders. Perfect outdoor spacing in any weather.
Drawer pulls, shelf pins, table legs, and decorative details. Precision for custom furniture.
Any task where "eyeballing it" just isn't good enough. Stop guessing, start measuring.
Using the Even Spacing Calculator is simple:
View the detailed table to see start and center measurements for every single piece. Export your layout to reference while working, or share it with your crew.
Like all ProDirt apps, Even Spacing Calculator follows our core principles:
To place n pieces evenly across a length L with a piece at each end, on-center spacing = (L − w) ÷ (n − 1), where w is the width of each piece. The clear gap between pieces is on-center − w. Mark every center from one end of the run so rounding errors can't accumulate.
Enter the total run length, the number of pickets or balusters, and each piece's width. The calculator returns the on-center distance and the clear gap, plus a mark-out list measuring every center from one end — so you tape once and mark instead of eyeballing gap after gap.
Yes. Anything laid out at equal intervals — shelf brackets, coat hooks, cabinet knobs, wall studs, screws, or garden plants — works the same way: give it the length, the count, and the item width, and it returns exact positions.
Yes — imperial fractions down to 1/64", rounded to a fraction you can read off a tape. Switch to metric and it works in whole millimetres instead.
The online calculator on this page is free with no sign-up. The Android app is free too (ad-supported); a one-time Pro unlock adds a printable PDF cut sheet and removes ads — never a subscription.
The web version does the full calculation — on-center, gap, and the mark-out list — right here in your browser. The app adds offline use on the job site, saved calculation history, and the Pro PDF cut sheet you can print and hand to your crew.
Stop calculating and start creating.
Download Even Spacing Calculator Free