Micro-ATX vs Mini-ITX Motherboards
Micro-ATX and Mini-ITX are both small motherboard sizes, but they are not close. Micro-ATX is a square 244 mm board with up to four expansion slots and usually four memory slots. Mini-ITX is a much smaller 170 mm square with exactly one expansion slot and, almost always, only two memory slots. Mini-ITX buys you a genuinely tiny PC; you pay for it in memory capacity, expansion and, usually, price.
The verdict
Choose Mini-ITX only if the case you want demands it, because you give up memory slots and expansion and rarely save money. For most compact builds Micro-ATX is the better buy: nearly the same footprint advantage over ATX, without the compromises.
The physical difference
These are fixed standards, the same for every board of that size.
Cases, cooling and what fits
Most of what people worry about here is decided by the case, not the board.
Which case takes which board
A case is built around one board size and accepts that size plus anything smaller, never anything larger. So a case rated for the larger of these two will happily take the smaller one, using a different set of standoffs, while the reverse does not physically fit. Picking the smaller board does not commit you to the smaller case.
Cooler height and graphics card length
Both limits are published by the case, not the board, and they are the two numbers most likely to catch you out in a small build. Check the maximum CPU cooler height and maximum graphics card length on the case you have in mind before you order either part.
What you give up, in numbers
How the two sizes actually differ once you look at every board on sale, rather than at what the standard permits. Measured across 149 Micro-ATX and 22 Mini-ITX boards at the retailers we track (136 and 18 in stock today), and updated daily.
The picks on each side
The cheapest board on each side, and the cheapest one that clears a floor worth clearing: enough power headroom for the socket’s top processor, and Wi-Fi 6E or better. Recalculated daily from live prices.
Micro-ATX
Best all-round
$99.99 · cheapest with the power headroom and Wi-Fi worth having
Mini-ITX
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Common questions
Is Micro-ATX the same as Mini-ITX?
No. Micro-ATX boards measure 244 × 244 mm and take up to four expansion cards. Mini-ITX boards are 170 × 170 mm with a single expansion slot. They also need different cases, although a Mini-ITX board will fit in a Micro-ATX case.
Can a Micro-ATX board fit in a Mini-ITX case?
No. Mini-ITX cases are built to the 170 mm board footprint and have no mounting points for a larger board. It works the other way round: a Mini-ITX board fits any Micro-ATX or ATX case.
Do Mini-ITX builds run hotter?
Usually yes, though it is the case rather than the board that causes it. A smaller enclosure has less room for airflow and for a large CPU cooler, so the same components typically run warmer in Mini-ITX than in a Micro-ATX build.
What is the downside of Micro-ATX?
Fewer expansion slots than ATX, and on the cheaper models fewer M.2 slots, weaker power delivery and sometimes only two memory slots. For a single-graphics-card gaming PC none of that usually matters.
What are the disadvantages of Mini-ITX?
Two memory slots instead of four, so you reach the capacity ceiling sooner and pay more per gigabyte to get there. One expansion slot, which the graphics card takes. Higher prices than an equivalent Micro-ATX board, because the layout is harder to engineer. And the cases they enable leave less room for cooling and are fiddlier to build in.
What CPU cooler should I use in a Mini-ITX build?
Whatever fits, which the case decides rather than the board. Every case publishes a maximum CPU cooler height, and in small enclosures that figure often rules out standard tower coolers and points you to a low-profile air cooler or a compact all-in-one. Check the case's clearance figure before choosing the cooler, not after.
Keep going
Browse every Micro-ATX board or Mini-ITX board with filters, put two specific boards head to head, or read up on choosing a case to fit the board you pick.