Fair value (1.2x sales) multiplies each year's revenue per share by the price-to-sales ratio investors have typically paid for SFIN.ME — the median of the last 20 fiscal years' average price over that year's revenue per share. The line extends forward with analyst revenue estimates (dashed).

Today's P/S (0.9x) is the current price over the last twelve months of revenue per share. Compare it to the typical ratio to see whether today's pricing is rich or cheap on sales.

Revenue comes from reported quarters; share counts come from market value divided by the share price, so buybacks and splits are handled correctly. The verdict calls a stock over- or undervalued only when the price sits more than 10% from the line.