Work out function point estimate instantly with clear inputs, formula shown and shareable results.
IFPUG function point analysis counts five function types and weights them by average complexity: external inputs at 4, outputs at 5, inquiries at 4, internal logical files at 10 and external interface files at 7. The result measures delivered functionality independently of technology, which is what makes it usable for cross-project productivity comparison where SLOC is not.
Function point count
UFP = 4 x inputs + 5 x outputs + 10 x internal files + 7 x external interfaces (average complexity weights)
A multiplier from 0.65 to 1.35 derived from fourteen general system characteristics such as performance and reusability. Many modern practitioners omit it as unreliable.
They apply well to transactional business applications. They fit poorly to algorithmic, real-time or infrastructure work where complexity is not proportional to data movement.