Key Points
The main difference between a mid-tower and full-tower PC case is the overall dimensions, with the full-tower case being larger and providing more room for expansion and better airflow.
Mid-tower cases average 18 x 18 x 8 inches while full towers are about 22 x 22 x 10 inches. The larger size accommodates more components.
Full-tower cases support larger E-ATX and XL-ATX motherboards, while mid-towers max out at standard ATX boards.
There are typically 4-7 PCI-e expansion slots in a mid-tower vs. 7-9 slots in a full tower. The extra room allows for more addons.
Cooling is better in full tower cases, with support for 10-15 fans plus large 480mm radiators rather than smaller 360mm radiators.
Drive bays vary greatly – full towers average 10-15 bays which helps for tasks like video editing while mid towers have 4-10.
Mid-Tower vs. Full-Tower Dimensions
The first obvious difference when comparing mid towers against full towers is the external dimensions. Since full tower cases are designed to fit more components, they are larger in every dimension:
- Height – Mid towers average 18 inches tall, while 22 inches is common for full towers.
- Width – Mid towers are around 8 inches wide internally while full towers are closer to 10 inches.
- Depth – The average mid tower depth is 18 inches vs. 22 inches for most full towers.
These extra inches give full tower cases more internal volume to work with for things like cooling and expansion. But it does mean they take up more room externally, something to consider for your desk space.
Motherboard Size Compatibility
One key component that influences case size requirements is the motherboard. The physical dimensions of the motherboard standard dictate some of the internal measurements for towers.
Most mid towers on the market can support these common motherboard sizes:
- Mini-ITX
- Micro-ATX
- Standard ATX
Some mid towers may even fit the larger E-ATX boards.
By comparison, full tower cases can fit all of those same standards and also accommodate XL-ATX motherboards – one of the largest consumer sizes available measuring 14 inches x 14 inches.
Having the room for these big boards allows you to take advantage of the extra PCIe expansion slots and ram capability they provide.
An XL-ATX board inside a cramped mid tower case would likely cause issues with spacing, airflow, and cable management. But inside a full tower they have plenty of room to breathe.
PCI Express Expansion Slot Differences
That brings us to PCI Express (PCIe) expansion slots, which allow you to install additional components like graphics cards, NVMe drives, WiFi/Bluetooth cards and more.
The number of PCIe slots is somewhat dependent on both the case size and which motherboard you choose since larger motherboards tend to have more built-in slots.
For mid towers paired with a standard ATX board, you can expect between 4-7 PCIe expansion slots in most models on the market today. High-end ATX boards may max out at 7.
By comparison, a full tower case paired with a high-end XL-ATX motherboard could potentially house 9 or more expansion slots. This gives you more flexibility for adding extra graphics cards for multi-GPU setups, additional NVMe SSD drives, and other addons.
Having room for more PCIe devices is one advantage of going with a more spacious full tower case, especially for enthusiasts who want to stuff their system full of the latest gear. A cramped mid size case may limit your expansion capability.
Cooling and Radiator Support
Another area where the larger internal dimensions of a full tower PC case come into play is with cooling and radiator support.
Having a case with good airflow and cooling is crucial to maintaining proper temperatures across critical components like your CPU and graphics card.
Most mid tower cases can accommodate 6-10 fans total scattered around the front, top, back and bottom portions of the chassis. Full tower cases almost double that capacity with room for 10-15 individual fans, sometimes more.
More fans means increased airflow which leads to lower temps. Components will thermal throttle and underperform if a case has poor ventilation.
Full towers also have enough depth and clearance to install very large external radiator liquid cooling units. A 480mm or 420mm radiator is commonly seen in these cases, using the extra height to maximum effect.
On the flip side, mid tower cases max out radiator support at 360mm or 280mm sizes. This is still suitable for the vast majority of CPU and GPU liquid cooling setups. But enthusiast overclockers looking to push components to the extreme will benefit from the increased cooling capacity of a full tower case.
Storage Drive Support
The final area where case dimensions and size plays a big role is with storage drive support – both hard disk drives (HDDs) and solid state drives (SSDs).
Tower cases include specially designed drive bays and mounts for adding storage drives. The exact configuration and number of bays can vary greatly between different models. But in general:
- Mid tower cases average between 4-10 total drive bays
- Full tower cases average between 10-15 total drive bays
More drive bays allows for installing more storage into your PC. This comes in handy for things like video editing rigs that require fast scratch disks and massive media storage capacity.
It also enables creating mega storage servers with 10+ drives. You would be limited in this regard with a mid size case.
Additionally full towers usually have more external 5.25" bays for optical disk drives (DVD/Blu-Ray) compared to mid towers, 2-5 bays compared to 1-3 respectively. Though optical media use is declining, an external bay can still come in handy occasionally.
5 Must-Know Case Facts
To recap, here are 5 key facts to be aware of with mid towers vs full towers:
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Mid towers are far more common and mainstream, purchased 3x more than full towers.
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Liquid cooling radiator support is available on both form factors. 360mm on mid, 480mm on full towers.
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Number of PCIe slots doesn‘t always match between case and motherboard. Always check compatibility.
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Some mid towers support E-ATX motherboards like full towers. But very large XL-ATX only fits in full tower cases.
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Drive bays vary drastically between models. Newer cases are getting creative with bay placement to fit more drives.
Which Should You Choose?
With all of those differences covered, which type of case is right for your next PC build or upgrade?
For most typical users doing gaming, office work, web browsing and basic content creation, a mid tower case is best matching their needs. Excellent airflow from 6-10 fans, liquid cooling support, 4-7 PCIe slots and room for up to 10 drives is more than enough capacity. And they take up less room on or under your desk.
But PC enthusiasts, hardcore overclockers, video editors, and data hoarders have special needs better addressed by full tower cases. The extra cooling, expansion room, drive bays and E-ATX/XL-ATX support are worthwhile upgrades for performance systems. You never feel cramped even with high-end gear.
Ultra towers exceeding 25 inches tall do exist going even more extreme. But diminishing returns starts kicking in unless you have an unusual scenario that specifically benefits.
For most intents and purposes, choosing between a quality mid tower and a full tower comes down to balancing size/space constraints against future expandability. Paying attention to component support ensures everything fits together properly during your build.
Hopefully this overview gives you a better understanding of how these two popular case form factors differ. Let me know if you have any other questions!