These are four calculators — occupant load, stair riser and tread, ADA ramp slope, and egress width — built from a verified subset of IBC and ADA figures, plus an explainer on why plumbing fixture counts do not get a fifth calculator. Every tool is a reference estimate, not a code determination; confirm the applicable edition and any local amendments with your local building department.
Before you use any of these: what they are and are not
Every calculator on this site is a reference and estimating tool, not a code determination. Each one applies a verified, deliberately limited set of IBC or ADA figures to the numbers you enter, and each shows its math and cites the exact code section and edition it draws from. None of them knows your project’s adopted code edition, local amendments, or occupancy classification. Confirm the applicable requirements with your Authority Having Jurisdiction (AHJ) before relying on any result.
The four calculators
| Calculator | Code source and edition | What it checks |
|---|---|---|
| Occupant load | IBC Table 1004.5 (2021/2024 IBC) | Floor area ÷ a per-function factor, for one space at a time |
| Stair riser and tread | IBC 1011.5 and 1011.10 (2021/2024 IBC) | Proposed riser height and tread depth against commercial, dwelling-unit, or spiral stair limits, including flight uniformity |
| ADA ramp slope | ADA 2010 Standards §405 / IBC 1012 | Rise ÷ run against the 1:12 accessible-route limit, plus the existing-building alteration exception |
| Egress width | IBC 1005 (2021/2024 IBC) | Occupant load × a capacity factor for doors, corridors, or stairways, checked against the applicable minimum |
Occupant load calculator · Stair riser and tread calculator · ADA ramp slope calculator · Egress width calculator
The one that is not a calculator, on purpose
A fifth topic, plumbing fixture counts, is not built as a calculator here. The underlying IPC and UPC fixture-ratio tables were not verified against a primary source during research for this batch, so no specific fixture-count number is asserted anywhere on this site. Instead, this explainer covers how the IPC and UPC differ, why California’s plumbing code uses its own occupant-load table, and where to find the current, verified numbers.
Where Groundbook fits
Groundbook’s document review reads a project’s code analysis sheet and compares the dimensions, schedules, and stated requirements on your drawings against the building code sources you upload for the review, flagging where they appear inconsistent — see how Groundbook checks local building codes and the building code compliance review. These calculators are standalone reference tools for the numbers themselves; a Groundbook review checks whether the numbers already on your drawings agree with each other and with the code sources you supply.