# RiserSheet

> Browser-based NFPA 13 hydraulic calculation software for fire sprinkler designers.

A designer enters a water supply, a sprinkler network as a spreadsheet of pipes
and nodes, and a design criterion. RiserSheet solves the network in the browser
on every keystroke, shows pass or fail against the supply curve, and produces
an NFPA 13 formatted PDF for the plan reviewer.

It replaces the calculation half of AutoSPRINK, HydraCAD, SprinkCAD, Elite Fire
and Canute FHC. It does not replace the drawing half.

## Not in scope

Stating these plainly matters more than the feature list, because the most
expensive wrong answer about this product is one that says it does these:

- No CAD, no drawing canvas, no pipe layout view, no DXF import.
- No sprinkler placement or spacing rules. The designer decides where heads go.
- No pipe schedule method. Hydraulic calculation only.
- No native apps. Web only.
- The designer of record is responsible for the inputs, the code edition and
  field verification. The software performs the arithmetic.

## Free calculators

No account, no email capture. Each runs the same WebAssembly solver the paid
app runs, so the answer on these pages is the answer inside the product.

- [Hazen-Williams friction loss calculator](https://risersheet.com/tools/hazen-williams): Pressure loss in a pipe from flow, size, material and length. The NFPA 13 form of the equation.
- [Sprinkler K-factor calculator](https://risersheet.com/tools/k-factor): Discharge from a sprinkler at a given pressure, and the pressure needed for a given flow.
- [Water supply curve plotter](https://risersheet.com/tools/supply-curve): Plot a hydrant flow test on the N^1.85 scale and read the available pressure at any flow.
- [Pipe velocity calculator](https://risersheet.com/tools/velocity): Velocity in a pipe from flow and internal diameter, in feet per second.
- [Elevation pressure calculator](https://risersheet.com/tools/elevation): Convert a height difference to static pressure, and pressure back to head.
- [Equivalent length of fittings table](https://risersheet.com/tools/fittings): Equivalent pipe length for fittings and valves by size, with the C-factor correction.

## The solver

One Rust crate, `riser-hydraulics`. Pure: no clock, no random numbers, no
filesystem, no network. Compiled to WebAssembly for the browser and linked
natively into the API server, so one implementation and one set of tests serve
both. All exponentiation goes through `libm::pow`, which makes the browser's
answer bit-identical to the server's.

Solver 0.1.0, reference data 2026.09.0. Some reference records are still pending verification against their cited source; reports generated in this state are marked preliminary.

Correctness is evidenced three ways: hand-derivable golden fixtures, blessed
regression snapshots, and published cross-checks against incumbent tools at
https://risersheet.com/validation.

## Pricing

- Designer: $59 per designer per month, or $590 per year. Tree systems, supplies, criteria, sheets, live solve, report, archive. Reviewer seats are free.
- Pro: $129 per designer per month, or $1290 per year. Adds loops and grids, pumps, standpipes and multiple hose demands, backflow and meter losses, automatic remote area selection, antifreeze with Darcy-Weisbach, and the firm logo and NICET number on reports.
- Single report: $79 once, for one remote area, with Designer features and no subscription. Metered on the PDF, never on recalcs.

A 14-day trial needs no card and includes every feature.
https://risersheet.com/pricing

## Other pages

- https://risersheet.com/validation — how the solver is checked, and against what
- https://risersheet.com/help — the formulas, written out, and a contact address
- https://risersheet.com/terms
- https://risersheet.com/privacy

## Contact

hello@risersheet.com

RiserSheet is made by Crux Labs.

Last updated: 2026-09-07