Reliability engineering calculators
Three single-purpose calculators that solve narrow but recurring problems in functional-safety and reliability engineering. All three run entirely in your browser — your inputs never leave your device. No account, no expiry, no telemetry.
λ → PFD Calculator
Convert dangerous failure rate (λ_DU) to PFD_avg (low-demand) or PFH (high-demand) and read off the SIL band. Annual or arbitrary proof-test interval, MTTR adjustable.
ISO 26262-9ASIL Decomposition Calculator
Pick a parent ASIL, get every permitted ASIL-X(Y) + ASIL-Y(Z) split per ISO 26262-9 §5.4.10, with the independence preconditions called out for each.
PRA · UncertaintyLognormal Monte Carlo
Drop in a median and error factor (EF). Returns mean, 5/50/95 percentiles, and a histogram from 10,000 lognormal samples. The right way to convert PRA point estimates into ranges.
Full toolFTA Studio (full app)
When the answer needs the whole tree: build, quantify, and audit a complete IEC 61025-compliant fault tree in your browser. Free Community edition.
Why we built these
Every functional-safety engineer has a small library of one-shot calculations they do over and over: convert a failure rate to a SIL band, sketch out an ASIL decomposition for a design review, propagate uncertainty on a single failure rate. Most of those live in personal Excel files that pre-date the engineer joining the team. That's fine until the spreadsheet has a subtle error or until a new starter needs the same calculation.
These three pages are deliberately narrow. They don't try to replace a full reliability suite — that's what the FTA Studio app is for. They're the quick-reference calculators that take 5 seconds to use and don't require opening a desktop tool.