Enter a failure rate and diagnostic coverage for each element. The calculator rolls them up to system SPFM, LFM and PMHF, checks them against the ASIL targets, and tells you which element is spending your budget.
| Element | λ (FIT) | Safe % | DCSPF % | DCLF % | λSPF+RF |
|---|
Runs entirely in your browser. Nothing is uploaded, stored, or sent anywhere.
A single-element calculation tells you whether one part can reach a target. It does not tell you whether your system does, because the system metrics are ratios of sums, and sums are dominated by their largest terms. A part with excellent coverage sitting next to a part with poor coverage does not average out to something acceptable — the poor one sets the result almost by itself.
That is why this tool highlights the dominant contributor. In most real designs one or two elements supply the majority of the escaping failure rate, and every hour spent improving coverage elsewhere is close to wasted. Load the example and change the microcontroller's coverage, then change the CAN transceiver's by the same amount, and watch how differently the system responds.
SPFM = 1 − Σλ_SPF+RF / Σλ_SRLFM = 1 − Σλ_latent / (Σλ_SR − Σλ_SPF+RF)PMHF ≈ Σλ_SPF+RF + T_life × Σi<j λ_latent,i × λ_latent,jThe dual-point term sums over unordered pairs of elements — two independent latent faults, in different places, coinciding inside the operating lifetime. That is a more faithful treatment than squaring the total latent rate, which would double-count and would also count each element against itself. It is still second order in λ, so it stays far below the single-point term in any realistic design; if it ever dominates your result, check the inputs before believing it.
FMEDA and FMEA review is one of our primary service lines, at board and silicon level. If the rollup is not landing where you need it, a gap review is the usual next step: one to two weeks, and it ends in a written report you keep. Every block in our safety soft-IP catalog ships with its own FMEDA and published SPFM/LFM figures, so you can see what a completed one looks like.
Each of these runs entirely in your browser. Nothing is uploaded, stored or sent anywhere, and none of them needs an email address.
See all 49 engineering tools →
We add tools here fairly often and write up the things worth writing up — a stackup that behaved oddly, a standard that turned out to be obsolete, a calculator that was quietly wrong. Join and you get told when something new lands.
One email a month at the very most, and usually less. No drip sequence, no sales cadence, no sharing your address with anyone. Unsubscribe whenever you like.