A fair value is an estimate, and estimates are wrong by something. The margin of safety is the discount a buyer demands before acting on one: the gap between the value and the price, measured against the value. Every workup in Stock Valuation Studio prints the margin and the buy price that follows from the margin you require.
The Two Formulas
The margin compares the price with the value, on the scale of the value itself:
The buy price runs the same idea in the direction a buyer needs. Choose the margin you require, and the buy price is the value discounted by exactly that margin:
One point causes real confusion, so it is worth stating plainly: the margin is measured on the value, not on the price. A buyer who requires a fifteen percent margin and buys at that buy price needs the price to rise about 17.6 percent before it reaches the value, because the rise is measured from the lower price. The Studio ladder of buy prices beside the present price keeps both figures in view.
A Worked Example: Apple
On October 27, 2026, the Studio headline value for Apple was $236.87, from the discounted cash flow model, and the market price was $342.58. The margin printed as it must when the price stands above the value:
A negative margin is not a margin at all; it is the distance the price would have to fall before any cushion existed, and the verdict read Overvalued. The buy prices that the same value supports at a range of required margins:
| Required Margin | Buy Price |
|---|---|
| 10% | $213.18 |
| 15% (the Studio preset) | $201.34 |
| 20% | $189.50 |
| 25% | $177.65 |
| 30% | $165.81 |
To see a positive margin on the same figures, suppose the price had been $180 instead. The margin would print at (236.87 minus 180) divided by 236.87, which is 24.0 percent: a real cushion, wider than the fifteen percent preset requires, and the buy signal would follow from it.
How Much Margin Is Enough
Graham asked for a substantial discount before he would call a price safe, and the reasoning has not dated: the margin is not a forecast, it is protection against the model being wrong, the record being flattered, and the future being ordinary. The Studio's preset of fifteen percent suits a diversified buyer working from filed figures. More is warranted where the value rests on a thin record, a cyclical peak, or a single optimistic model; less can be defended where several models agree and the balance sheet is strong. What the margin should never do is shrink because the buyer has fallen for the company. Set the requirement on the Assumptions card before you look at the price, not after.
Where the Margin Reads Best
Best for profitable, established companies whose value several models can state. The margin is only as sturdy as the value under it, and it reads best where the discounted cash flow, the multiples, and the forward estimate land in the same neighborhood. On those companies the margin is the deciding question: how much cushion the price leaves against the value being wrong.
Not decisive on a single fragile value. Where the headline rests on one optimistic model, or on earnings at a cyclical peak, a wide printed margin can flatter. The cure is a wider required margin, set before the price is seen, and a read across the full roster on the models hub, where the models that disagree are printed beside the ones that agree.
Not available where no model prints a value. For a company with no positive cash flow, no earnings, and no dividend, the workup reports that no reliable value can be stated, and there is no margin to read. The better first tool for those names is the revenue-build DCF, which builds cash flow from revenue rather than from a base that does not exist.
Questions
Why is the margin measured on the value and not the price? Because the value is the estimate being protected. Measuring against the value keeps the meaning fixed: a fifteen percent margin always means the price sits fifteen percent below what the workup says the company is worth, whatever the price happens to be.
Does the margin use the DCF value? It uses whichever model the headline is set on. The Studio chooses the headline by a fixed cascade, discounted cash flow first, and the selector on the workup lets you set the headline on any of the thirty-one models. The margin, the buy price, and the verdict all re-key to the model you choose.
What verdicts does the Studio print? Undervalued when the margin is positive, Fairly valued when the price stands within ten percent below the value, and Overvalued beyond that. The thresholds are fixed and stated, so the same figures always earn the same verdict.
Free Tool
The band at the head of every workup shows the fair value, the current price, the margin of safety between them, and the buy price at your required margin, preset to fifteen percent. Change the required margin on the Assumptions card and the buy price moves with it.
Margin of Safety CalculatorOpen in Stock Valuation Studio →Twelve Stocks Where the Margin Decides
Every tile opens Stock Valuation Studio. Enter the ticker there and read the margin of safety on the workup band.