Input Form
Example Data Table
| Scenario | Total Rise | Total Depth | Riser | Tread | Walkway | Rear Clear | Seats/Row | Sections | Row Count | Capacity |
|---|---|---|---|---|---|---|---|---|---|---|
| School Gym | 2400 mm | 9000 mm | 200 mm | 750 mm | 1200 mm | 600 mm | 20 | 1 | 9 | 180 |
| Outdoor Field | 3000 mm | 12000 mm | 190 mm | 800 mm | 1500 mm | 800 mm | 30 | 2 | 12 | 720 |
| Temporary Event | 1800 mm | 6500 mm | 225 mm | 700 mm | 1000 mm | 500 mm | 16 | 1 | 7 | 112 |
Formula Used
The calculator finds the maximum rows allowed by both vertical height and horizontal depth. It then uses the smaller value as the governing row count.
- Usable Depth = Total Depth − (Front Walkway + Rear Clearance)
- Rows by Height = floor(Total Rise ÷ Riser Height)
- Rows by Depth = floor(Usable Depth ÷ Tread Depth)
- Row Count = min(Rows by Height, Rows by Depth)
- Capacity = Row Count × Seats per Row × Sections
- Orderable Rows = ceil(Row Count × (1 + Waste%))
How to Use This Calculator
- Select a unit system and keep all inputs consistent.
- Enter total rise and total depth available for the bleachers.
- Set target riser and tread values based on your design intent.
- Add walkway and rear clearance to reserve circulation space.
- Enter seats per row and sections to estimate capacity.
- Click Calculate to see the governing row count and checks.
- Use CSV or PDF downloads to share the report.
Project Inputs That Control Rows
This calculator converts available rise and usable depth into a practical row count. The governing limit is the smaller of the height-based rows and depth-based rows, so measure the footprint and elevations carefully. With 2400 mm rise and a 200 mm riser, the height limit is 12 rows, but depth reserves can reduce the final count. The results also show used and remaining space for planning.
Interpreting Height Versus Depth Limits
Height-limited layouts appear when a roof, canopy, or sightline cap controls the build. Depth-limited layouts appear when the footprint is tight or circulation zones are generous. When the two limits are close, small changes to tread or riser may add or remove a full row, affecting overall capacity.
Capacity Planning and Section Splits
Capacity is rows × seats per row × sections. Splitting a long stand into sections for access aisles or structural breaks scales total seating while keeping the same row geometry. Seat spacing can estimate bench length per row, helping align assumptions with ordering and installation planning. Run alternate seat counts to see how capacity shifts without changing geometry.
Allowances, Clearances, and Constructability
Walkway depth and rear clearance are reserved first, then usable depth is checked against the tread stack. This is planning guidance, not a substitute for project requirements. The waste factor adds margin for fabrication tolerances, field trimming, and late layout adjustments that can occur during delivery and assembly. Use the orderable row count when you want conservative allowances.
Reporting, Review, and Field Verification
Use downloads to document inputs and share them with the site team. Verify rise, depth, and reserved zones in the field before final orders, especially on sloped or irregular grades. If depth governs, consider adjusting tread or reserves. If height governs, consider whether a different riser target fits your intent.
Additional Example Data
| Use Case | Total Rise | Total Depth | Riser | Tread | Walkway | Rear Clear | Seats/Row | Sections | Expected Rows | Expected Capacity |
|---|---|---|---|---|---|---|---|---|---|---|
| Small Indoor Stand | 2100 mm | 8200 mm | 210 mm | 760 mm | 1100 mm | 600 mm | 18 | 1 | 8 | 144 |
| Two-Section Sideline | 2800 mm | 10500 mm | 200 mm | 780 mm | 1500 mm | 700 mm | 28 | 2 | 10 | 560 |
| Compact Footprint | 2600 mm | 7800 mm | 190 mm | 800 mm | 1400 mm | 700 mm | 22 | 1 | 7 | 154 |
FAQs
1) Why does the calculator show two different row limits?
Rows are limited by available rise and usable depth. The governing row count is the smaller value so the layout fits both vertically and horizontally.
2) What should I enter for walkway and rear clearance?
Enter the space you want to reserve for circulation, rails, and access. These values reduce usable depth and can change the governing row count.
3) Does seat spacing affect row count?
Seat spacing does not change row count. It is used only to estimate bench length per row when you also enter seats per row.
4) How is seating capacity calculated?
Capacity equals rows multiplied by seats per row and then multiplied by the number of sections. Adjust seats per row or sections to model different layouts.
5) What does the waste factor do?
Waste adds a buffer to the row count for ordering and field adjustments. It helps cover trimming, tolerances, and minor design changes during construction.
6) Why might my field count differ from the result?
Field constraints like structural members, rail posts, access aisles, and local requirements can reduce usable space. Treat the output as planning guidance and verify dimensions on site.
7) Can I use imperial and metric interchangeably?
Yes, but do not mix units in one calculation. Select one unit system and enter all dimensions consistently to avoid incorrect row counts.