Set garden rail spacing confidently using simple inputs. Check compliance against your selected opening limit. Export results to files for easy records.
| Scenario | Total length | Baluster width | End clearance | Max opening | Balusters | Internal opening | Compliance |
|---|---|---|---|---|---|---|---|
| Garden deck rail sample | 2,400.00 mm | 38.00 mm | 50.00 mm | 100.00 mm | 18 | 95.06 mm | PASS |
The calculator assumes equal internal gaps between balusters, plus equal end clearances. Let L be the rail length, W the baluster width, C the end clearance (each end), and N the baluster count.
Without optimization, the tool selects the smallest N that keeps openings at or below your maximum. With optimization, it selects a compliant N that best matches your target gap.
Accurate opening control reduces climbing hazards and keeps small pets from slipping through. This calculator converts your rail length, baluster width, and end clearances into a compliant spacing layout. It also highlights the largest opening, because end gaps often govern the final safety check on garden decks and raised walkways. Use it early, before ordering materials, to avoid costly changes on site.
The tool balances length using L = N·W + (N−1)·g + 2·C, where g is the internal clear opening. For a chosen maximum opening M, it searches for the smallest baluster count that keeps max(g, C) ≤ M. This approach produces a practical buildable pattern without guesswork. If the computed gap becomes negative, the run is too short for the selected components.
End clearance should reflect post hardware, brackets, and alignment tolerance. If you plan to notch rails or use hidden fasteners, measure the true clear distance between post faces after installation. Using realistic clearances improves the predicted opening and reduces on‑site trimming or forced rework. On sloped garden edges, recheck clearances at both ends to account for level adjustments.
When you enable optimization, the calculator looks for a compliant baluster count that best matches a target opening. This is useful when you want consistent visual rhythm, or when you are matching an existing section. The target is a preference, while the maximum opening remains the governing constraint. For long runs, a slightly smaller gap can improve stiffness and reduce rattle in windy conditions.
Use the export buttons to store a spacing record with your project notes. The CSV is convenient for estimating material quantities, while the PDF is suitable for sharing with a client or crew. Recalculate if you change baluster size, rail length, or post layout, and keep units consistent. For repeat sections, reuse the same inputs to standardize appearance across the garden. Before cutting, mark centers with a story pole, then dry-fit balusters to confirm the measured openings match your plan under real conditions.
Use the limit required by your local safety code or project specification. Many residential applications use 100 mm or about 4 inches as a common benchmark.
The largest gap can occur at the ends near posts. If end clearance exceeds the internal spacing, it becomes the controlling opening and can cause a fail result.
This calculator assumes identical baluster widths for consistent spacing. If you mix profiles, compute using the largest width or split the run into separate sections and calculate each.
Reduce end clearance, choose narrower balusters, increase rail length, or relax the opening limit if permitted. A negative gap indicates the components physically do not fit.
Measure the clear distance between the inside faces of the end posts at the rail line. Take several measurements and use the smallest value to protect against tight spots.
No. Optimization only chooses a baluster count that best matches your target gap while still keeping the largest opening at or below your maximum limit.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.