FlexATX
![ATX motherboard size comparison; rear is on left.
FlexATX (229 × 191 mm)
microATX (244 × 244 mm)
Mini ATX (284 × 208 mm)
Standard ATX (305 × 244 mm)
Extended ATX (EATX) (305 × 330 mm)
WTX (356 × 425 mm)](/Images/godic/202501/13/Atxscale.svg3252.png")
FlexATX is a motherboard form factor derived from ATX. The specification was released in 1999 by Intel as an addendum to the microATX specification. It uses a subset of the motherboard mounting holes required for microATX and the same I/O plate system as ATX and microATX.