Formula
Margin of Safety = (Intrinsic Value − Purchase Price) ÷ Intrinsic Value × 100%
Formula
Target Buy Price = Intrinsic Value × (1 − Margin of Safety %)
Compare
| IV Was Actually... | You Estimated $100, Paid $70 | Outcome |
|---|---|---|
| $100 — you were right | Paid $70 for $100 of value | ~43% upside. Excellent return. |
| $80 — you were 20% too optimistic | Paid $70 for $80 of value | 14% upside. Still a profit despite being wrong. |
| $50 — you were badly wrong | Paid $70 for $50 of value | 29% loss. The MoS wasn't enough — but a tighter estimate or wider MoS would have kept you out. |
Compare
| Margin of Safety | Risk Level | When Appropriate |
|---|---|---|
| >40% | Low — significant cushion against error | Best opportunities — rare, usually during market panics or ignored sectors |
| 25-40% | Moderate — typical value investing range | Quality business at a meaningful discount — the core of a value portfolio |
| 10-25% | Higher — your estimate must be quite accurate | Only for businesses with very predictable, stable earnings |
| <10% or negative | High — you are essentially paying full price or more | Avoid unless you have exceptional conviction and a very long time horizon |
Key point
The margin of safety is not the same as being cheap. A stock trading at 5x earnings is not automatically a margin of safety — if earnings are about to collapse, the true intrinsic value is much lower than current earnings suggest. Margin of safety applies to your estimate of intrinsic value, not to arbitrary price ratios. You need both: a sound estimate AND a significant discount to that estimate. And the estimate you discount must itself be conservative — a 30% discount taken off an over-optimistic value protects nothing. The first-order formula in this module assumes your central estimate is honest; the master-concept module makes the harder demand explicit: run the discount against the bear end of your range, not the best guess. Treat the arithmetic here as the entry point, not the finish line.
Key point
Why value investors hold cash: Waiting for adequate margin of safety means you often sit on the sidelines. This is uncomfortable — markets go up, others are making money, and you feel like you are missing out. But deploying capital without margin of safety is speculation, not investment. The discipline to wait is the price you pay for downside protection.
Try it
Check-in
Check-in
Sit with the ideas.
You estimate intrinsic value at $100/share (this is your CENTRAL estimate), with ±25% estimation uncertainty. Applying the first-order mechanic, what price gives you a 30% margin of safety against that central estimate?