How-to guide

How to use the Pre-Mortem Tool

The best way to de-risk a big decision is to imagine it already failed. This makes that structured. Here's how, with three examples.

A pre-mortem flips optimism into foresight: assume the decision has already failed, then work backwards to why. This makes that a quick, structured exercise before you commit.

What this tool does

You state the decision, list the ways it could fail with a likelihood and impact for each, and get a ranked risk list plus a plain verdict on whether to proceed.

Who it's for

Founders and leaders about to make a big, hard-to-reverse call — a launch, a hire, a big commitment.

How to use it — step by step

  1. State the decision. The bet you're about to make.
  2. List the ways it fails. Be honest and specific.
  3. Rate likelihood and impact. For each failure mode.
  4. Read the ranked risks + verdict. What to fix before you commit.

How to read your result

A single 'Likely + Fatal' risk should stop you until it's mitigated. The verdict isn't about killing the idea — it's about fixing the one or two things that would actually sink it.

Worked examples

The same tool behaves differently depending on what you put in. Here are 3 situations.

Launching a feature

Inputs: Six months of build.

What the tool shows: Surfaces 'customers don't want it' and 'we run out of cash' — ranks the fatal ones.

What to do: Validate demand and cash before committing the six months.

A senior hire

Inputs: An expensive, culture-shaping role.

What the tool shows: Ranks mis-hire and runway risks.

What to do: De-risk with references and a trial project.

Signing a big customer

Inputs: A deal that reshapes the roadmap.

What the tool shows: Surfaces concentration and delivery risk.

What to do: Guard against over-dependence on one account.

Common questions

Isn't this just being negative? No — it's foresight. Naming risks early is how you avoid them.

How long does it take? A few minutes — that's the point.

What if everything's 'Fatal'? Then the decision needs rework before you commit.

A helpful estimate, not a guarantee. This tool works only off the numbers and assumptions you enter — it can't see your whole picture. Use it to get oriented and pressure-test your thinking, then sanity-check the big calls with an advisor. It isn't financial, tax, or legal advice.