Payback Period

We use a simple payback formula to measure the relative pricing of investments. Bear in mind that some investments are higher risk than others and therefore command a higher risk premium and shorter payback.

The formula requires five inputs:

  • Free Cash Flow (FCF), normally calculated as Operating Cash Flow (OCF) minus Capital Expenditure (Capex) or EBITDA (Earnings before Interest, Tax, Depreciation & Amortization) minus Capex, Tax and expected Increases in Working Capital;
  • Expected Growth in FCF, normally equal to Revenue growth plus any adjustment for improving margins;
  • Market Capitalization (Market Cap), the number of shares in issue multiplied by the current market price;
  • Surplus Cash (Cash and Short-term Investments); and
  • Total Debt (including capitalized leases)

Using a spreadsheet, simply calculate the number of years of FCF, allowing for growth, that it will take to repay Market Cap plus Net Debt (Debt minus Surplus Cash).

Potential issues

Stock Based Compensation

Normally added to Operating Cash Flow (OCF), stock-based compensation is still an expense of doing business and dilutes the holdings of existing shareholders. Our preferred treatment is to exclude from OCF (as it is from EBITDA) and to treat stock-based compensation as a source of financing (Cash Flows from Financing Activities).

Software Development

Make sure that capitalized software costs (normally shown as Intangibles) are included as Capex. These are often stated as a separate item on the Cash Flow Statement and omitted as a deduction from FCF.


Regular acquisitions may enhance revenue growth (and margins) but absorb free cash flow. Adjust revenue growth to exclude growth from acquisitions or deduct acquisitions from FCF, otherwise you will be double-counting.

Disposals, Spin-offs & Discontinued Operations

FCF needs to be adjusted for disposals, spin-offs and discontinued operations. If the operation was making losses then FCF will increase.

Bear in mind when evaluating potential growth that discontinued operations may be excluded from past performance. Companies are often motivated to dispose of under-performing operations because they reflect poorly on management. Future expected growth should be adjusted to reflect the likelihood of further poor performance.

Margin of Safety

We have simplified our model by eliminating margin of safety and instead using a single variable — the payback period — to reflect our estimate of risk/uncertainty.

Payback Period

Stocks with stable revenue and earnings streams justify higher prices which are recognized through a longer payback period. We may use a payback period of 10 years for volatile stocks, while blue chip stocks may justify a payback period of 13 years or more.


A simple formula with few variables, Payback eliminates the need to estimate the cost of capital, used to discount future cash flows in a normal DCF model, and project an exit value/exit multiple.

Payback adjusts FCF for expected growth, providing a far more useful measure than normal multiples (e.g. P/E) which do not.

Payback does not assume a linear relationship between value (P/E) and expected growth as in the PEG ratio. The relationship more closely resembles an exponential curve.

Payback does not need to be adjusted for stock buybacks.


Future growth is not always consistent and is subject to forecast error.