Margin of SafetyMOS
The margin of safety is the gap between a stock's estimated intrinsic value and its market price. Value investors buy only when the price is well below their estimate, so that errors or bad luck still leave room to avoid major losses.
Every valuation is a guess. The margin of safety admits that: instead of buying when price equals your estimate of value, you wait until it is clearly below it. The discount is a cushion against mistakes. Popularised by Benjamin Graham and Warren Buffett, it is the backbone of value investing. This entry explains the idea, the calculation and how investors set their margin.
- Category
- Fundamentals and Macroeconomics
- Reading time
- 3 min
- Also called
- Safety margin, Margin of safety principle
- Updated
Margin of safety in plain words
The margin of safety is an investing principle of buying stocks when the market price is below their actual value.1
It acts as a built-in cushion that tolerates some losses while protecting against major ones.1
Value stocks are those trading below their intrinsic value — the opportunity the margin of safety looks for.2
How to apply a margin of safety, step by step
Estimate intrinsic value
Using cash flows, earnings or assets. See Discounted Cash Flow.
Choose your margin
Larger for riskier or less certain businesses.
Set a buy price
Intrinsic value × (1 − margin).
Wait for the price
Patience is part of the method.
Buy below the target
The discount is your cushion.
Reassess regularly
Values change as businesses change.
Worked examples
Example 1 — Setting a buy price
Buy at $60 or lessYou estimate intrinsic value at $80 and want a 25% margin of safety.
| Buy price | $80 × (1 − 0.25) = $60 |
Investors set their margin of safety according to the level of risk they see.1
Example 2 — Measuring the margin
30% cushionIntrinsic value $50, market price $35.
| Margin of safety | ($50 − $35) ÷ $50 = 30% |
The bigger the gap below value, the bigger the cushion against downside risk.1
Example 3 — The cushion at work
Error absorbedYou bought at $60 with an estimate of $80, but the true value turns out to be $68.
| Estimate error | −15% |
| Still above your price | $68 > $60 |
Buying below estimated value leaves room for valuation mistakes without a loss.1
Small vs large margin of safety
| Aspect | Small (≈10%) | Large (≈40%+) |
|---|---|---|
| Suits | Stable, predictable firms | Uncertain or cyclical firms |
| Opportunities | More frequent | Rarer |
| Protection | Less | More |
| Risk of missing out | Lower | Higher |
How investors use a margin of safety
Value investing
The core rule for entries. See Growth vs Value Stocks.
Position sizing
Bigger margin, bigger conviction. See Position Sizing.
Bond and credit analysis
Cushions against default.
Business budgeting
Sales above break-even.
Advantages and disadvantages
Advantages
- Protects against valuation errors.
- Encourages disciplined, patient buying.
- Limits downside in bad scenarios.
Disadvantages
- Intrinsic value is an estimate.
- Great companies rarely trade at big discounts.
- Cheap stocks can be cheap for good reasons.
Going deeper
Read as far as you need. Each level builds on the one before it.
What goes into value
Beginner
Investors look at management, performance, governance, earnings and assets to estimate a stock's intrinsic value.1
Qualitative and quantitative
Intermediate
Both numbers and judgement are used to decide how far below the price target to buy.1 See Economic Moat.
In accounting
Advanced
In business budgeting the same term means how far sales can fall before hitting break-even — a related idea of cushion. See Net Income.
Common mistakes
Overconfident valuations
The cushion only works if estimates are honest.
Same margin for every stock
Riskier businesses need more.
Ignoring business decline
Value can fall below your price.
Never buying
Excessive margins mean missed opportunities.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- The margin of safety is the discount to intrinsic value.
- It cushions against valuation errors.
- Riskier businesses need bigger margins.
- It is central to value investing.
- It depends on honest, careful valuation.
Frequently asked questions
What is a good margin of safety?
Who invented the concept?
Does it apply to growth stocks?
Further learning
- Discounted Cash Flow
A way to estimate value.
- Economic Moat
What protects that value.
- Growth vs Value Stocks
Where the principle applies.
- Price-to-Book Ratio
A simple value check.
Sources
This article is written in our own words. The sources below support the specific facts, rules and figures marked with a number in the text. Links open the original publisher’s page.
- Corporate Finance Institute. Margin of Safety (opens in a new tab) Checked .
- Corporate Finance Institute. Growth Stocks vs Value Stocks (opens in a new tab) Checked .
Educational content, not financial advice. Examples use hypothetical prices and simplified costs; actual fees, margin rules and regulations vary by broker, market and country. We are not affiliated with any publisher linked above. Last reviewed . Report an error or request a source credit.