What Is a Flex in Fantasy Football? Flex Rules and Who to Start
Fantasy Football Glossary · By Elliot — Founder, Dynasty Dealer · Published 2026-10-02
A flex is a fantasy football lineup slot that can be filled by a running back, a wide receiver or a tight end, whichever you choose. Most leagues have one or two flex spots next to the fixed QB, RB, WR and TE slots. The flex lets you start an extra player from your deepest position each week; a superflex goes one step further and also accepts a quarterback.
Who can play in the flex
A standard flex accepts running backs, wide receivers and tight ends. Some leagues narrow it (a WR/TE flex, for example) and some widen it: a superflex also takes a quarterback, which roughly doubles how many quarterbacks start each week. Check your league settings for which positions each flex slot accepts.
Who to start at flex
Start whichever eligible player projects for the most points, not the position that feels safer. Scoring matters: in PPR, high-target receivers usually win the flex; in standard scoring, running backs with touchdown chances often do. When two players are close, lean on volume, because targets and carries are steadier than touchdowns.
The late-kickoff trick
Lineups lock player by player as each game kicks off. Putting your latest-kickoff player in the flex keeps your options open: if an earlier starter is ruled out, you can still move a late player into his position slot and use the flex for someone else.
Can a quarterback play in the flex?
Only in a superflex, or another flex slot that lists QB as eligible. A standard flex is for running backs, wide receivers and tight ends.
Should I put a running back or a wide receiver at flex?
Whichever projects higher for the week. Your scoring decides the tiebreaks: PPR tilts toward receivers, standard toward running backs with touchdown upside.
How many flex spots do most leagues have?
One or two. More flex spots make lineups deeper and raise the value of running back and wide receiver depth.