What AFFO is trying to measure
Adjusted funds from operations, or AFFO, is a REIT analysis metric used to move closer to recurring distributable cash flow than plain FFO. Nareit-defined FFO is useful because it removes some GAAP distortions such as real-estate depreciation and gains or losses on property sales, but many analysts and issuers still think FFO is too early in the cash-flow bridge because it can leave in non-cash straight-line rent and ignore recurring property-level cash spending.
That is why AFFO starts from FFO and then deducts or normalizes the recurring items that matter to the real cash economics of a leased property portfolio. Common deductions include straight-line rent adjustments, maintenance-style capital expenditures, recurring tenant improvements, and recurring leasing commissions. Some issuers also make other recurring or non-cash adjustments, which is why AFFO is widely used but not standardized in exactly the same way as Nareit-defined FFO.
For investors, the practical question is usually not just What is AFFO? but What does that imply for the dividend? A useful AFFO calculator therefore needs to go beyond one headline number and show how the adjustments changed FFO, what AFFO looks like on a per-share basis, and whether the annual common dividend is still covered once those recurring cash demands are recognized.