Margin of Safety Calculator
Margin of safety is a core principle of value investing, popularized by Benjamin Graham. It measures how much cheaper a stock is trading relative to your estimate of its true (intrinsic) value. By buying at a discount, you create a buffer against valuation errors and unexpected adverse events. A large margin of safety means you need to be less precise about the exact intrinsic value, because even if your estimate is somewhat off, the stock is still cheap enough. This calculator takes your intrinsic value estimate and the current market price, then computes the margin of safety and the maximum price you should pay to achieve a target safety margin.
Margin of safety formula
Margin of safety = (intrinsic value - market price) / intrinsic value
Max buy price = intrinsic value * (1 - target MOS%)
A positive margin of safety means the stock trades below intrinsic value. A negative value means it trades above intrinsic value (overvalued). The maximum buy price is the highest price at which you still maintain your desired margin of safety.
Applying margin of safety in practice
- Graham recommended requiring at least a 30% margin of safety for net-net stocks and at least 20% for higher-quality businesses.
- The intrinsic value estimate should be conservative; if uncertain, use a range and require a margin relative to the lower end.
- Margin of safety is not a guarantee; even deeply discounted stocks can continue to fall if the business deteriorates.
- Value investors typically hold many positions so that errors in individual valuations are diversified away.
- SEC filings (10-K and 10-Q on EDGAR) provide the financial data needed to estimate intrinsic value through DCF or asset-based methods.
Frequently asked questions
What is margin of safety in investing?
Margin of safety is the difference between a stock's intrinsic (estimated true) value and its current market price, expressed as a percentage of intrinsic value. Buying at a significant discount to intrinsic value provides a cushion against estimation errors and unforeseen negative events.
Who popularized the margin of safety concept?
Benjamin Graham introduced the concept in 'Security Analysis' (1934) and 'The Intelligent Investor' (1949). He advocated buying stocks only when they traded at a significant discount to intrinsic value, typically 30% or more, to protect against errors in valuation.
How do I estimate intrinsic value?
Common intrinsic value methods include discounted cash flow (DCF) analysis, which discounts projected future free cash flows; asset-based valuation; and comparable company multiples. Each method has assumptions and estimation risk, which is exactly why a margin of safety is important.
What is a sufficient margin of safety?
Benjamin Graham typically required a 30 to 50% margin of safety. The required margin depends on how confident you are in your intrinsic value estimate and how volatile the business is. For stable, high-quality businesses, 20% may suffice; for speculative or cyclical businesses, 50% or more may be prudent.
Does margin of safety guarantee a positive return?
No. Intrinsic value estimates can be wrong, and market prices can stay depressed for years. Margin of safety reduces but does not eliminate investment risk. The concept is about improving the probability of a good outcome and limiting downside, not about certainty.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.