Complete Guide to PC Case Sizes and Dimensions [Custom PC]

PC case sizes are broadly categorized as mid-tower cases, full-tower cases, and so on.

Depending on the size, the upper limit of performance, placement options, airflow, expandability, and ease of assembly will vary.

Choosing an inappropriate size may prevent required components from fitting or make future upgrades impossible, so it is important to understand these points in advance.

Basic knowledge about PC case brands is covered, along with how to choose from the perspectives of performance and compatibility.

≫ Related article: How to Choose a DIY PC Case [Performance / Features / Compatibility]

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About PC case sizes

PC case size correlates with the performance ceiling, placement options, airflow, expandability, and ease of assembly.

Therefore, it is advisable to select a case size that fits individual needs after understanding the characteristics.

The performance “ceiling” is largely determined

The overall performance “ceiling” is largely determined by PC case size.

DIY PC’s basic performance is defined by the CPU / GPU / memory / storage, among these, the more powerful the CPU and GPU, the larger the physical size tends to be. A PC case that can accommodate those parts is required.

For CPU, the chip’s physical size does not change with performance, but higher-end models generate more heat and therefore require CPU coolers with greater cooling capacity.

High-performance CPU coolers also tend to be physically larger.

For GPU, the higher the performance, the larger the graphics card becomes, so it will not fit in a small case.

In particular, the length of the graphics card (depth when viewed from the PC case front) often becomes the limiting factor.

As a result, installing a high-end graphics card generally requires a larger case.

Thus, a small PC case cannot accommodate high-performance CPU and GPU, effectively limiting builds to the low-end to mid-range.

Because the case size sets a performance “ceiling,” those aiming to build a high-performance gaming PC or workstation should consider at least a mid-tower case.

Conversely, those preferring a compact PC case should note that performance will be constrained by the physical size of the CPU cooler and GPU, depending on the case size.

CPU cooler height is constrained by case width, and GPU length is constrained by case depth.

Maximum supported dimensions are specified in the PC case’s specifications.

Check each component’s size against the case limits.

Also note the power supply unit has a depth specification; checking these three items is essential.

For those using the tool developed by the author—where “estimate,” “compatibility check,” and “power calculation” can be performed simply by selecting PC parts—the tool can also check part lengths and case dimensions/size fit. Feel free to make use of it.

≫ Related tool: DIY PC Parts Estimator & Compatibility Check Tool

Airflow & cooling performance

PC case size affects airflow potential, CPU cooler flexibility, and overall cooling performance.

Larger cases provide more internal volume, making it easier to secure airflow and achieve the intended cooling performance of components.

Large air coolers for CPU and liquid-cooling radiators can be installed, reducing thermal concerns when building a high-performance gaming PC or creator PC.

Ample space also allows heat-generating components such as the CPU, GPU, and PSU to be placed further apart.

For example, the graphics card can be positioned away from the power supply, reducing mutual heat interference.

This improves the efficiency of cooling across components.

In contrast, small cases pack components tightly, making airflow harder to secure and increasing proximity among heat sources.

Tall tower air coolers may be difficult to use, radiator sizes may be limited, or there may be no radiator support at all.

In this way, case size changes airflow options, CPU cooler flexibility, and cooling performance.

PC placement

PC placement is heavily influenced by case size.

The larger the case, the more limited the installation options.

Full-tower and mid-tower cases have considerable height and depth, often requiring under-desk space or a dedicated rack.

Meanwhile, mini-tower and slim cases are compact and can be placed on a desk or in tighter spaces.

From the perspectives of airflow and cable management, selecting an appropriate placement is also important.

Positioning in a well-ventilated area helps maximize PC performance.

Exhaust typically exits from the rear, so placing the back of the case too close to a wall may hinder heat dissipation and reduce performance.

Therefore, when choosing a PC case, it is important not only to ensure that components will fit but also to confirm that the case will physically fit in the intended location.

Ease of assembly

Larger PC cases simply have more internal space, making assembly work easier.

Hands can move more freely inside the chassis, allowing stress-free installation of the motherboard, graphics card, power supply, and other components.

Interference risk between parts is reduced as well.

Cable routing is easier, enabling tidy, organized cabling.

Fewer cables will touch components, improving appearance and preventing airflow obstruction.

Expandability: number of components

Expandability, simply put, refers to how many components can be installed.

The greater the expandability, the more memory, storage, and expansion cards can be added later.

Accommodating many components requires a larger case. In this sense, “PC case size = expandability.”

Therefore, smaller cases may not accept larger parts or may limit the number of drives/cards, forcing a narrower parts selection.

Conversely, larger cases generally offer high expandability, so typical configurations have sufficient size and slot headroom for flexible builds.

Those who do not want parts size or quantity restricted by case size should consider at least a mid-tower.

Even with the same mid-tower form factor, the specifications of PC cases can vary in terms of what and how much can be installed, so please check accordingly based on your own build.

Types and list of PC case sizes

PC cases are classified into several types by size and shape.

Each size has distinct characteristics, so it is important to choose one that matches individual needs.

First, review representative images and approximate sizes by category.

PC Case	Image	Size	Weight
Full Tower		Height/Depth: approx. 55–65 cm Width: 25–30 cm	Approx. 15–20 kg
Mid Tower		Height/Depth: approx. 40–55 cm Width: around 20 cm	Approx. 3.5–8 kg
Mini Tower		Height/Depth: approx. 30–40 cm Width: 15–20 cm	Approx. 3.5–5 kg
Slim		Height/Depth: approx. 30–40 cm Width: around 10 cm	Approx. 3–5 kg
Small		Height/Depth: approx. 10–20 cm Width: 5 cm	Approx. 2 kg
Cube		Approx. 25–50 cm	–
Horizontal Desktop		Width/Depth: approx. 30–40 cm Height: around 10 cm	Approx. 3.5 kg

Regarding size-based classifications of PC cases, there is no strict industry-wide definition such as “from X to Y cm equals ‘○○ tower.’”

Depending on the manufacturer or retailer, cases with similar overall dimensions may be categorized differently.

The sizes listed in the table were derived by comparing many case specifications and vendor-stated categories and narrowing to approximate ranges.

Among these, mid-tower cases are the most numerous and popular with users.

They offer sufficient expandability for high-performance, high-load use such as 3D gaming and creative work, and they leave room for future expansion, allowing flexible upgrades.

Mid-tower cases

Mid-tower cases are the most common among PC cases and strike a good balance between expandability and size.

Height and depth are roughly 40–55 cm, and width is around 20 cm—standard dimensions for desktop PCs.

This size typically supports ATX motherboards and accommodates large high-performance CPU coolers and graphics cards, with ample drive capacity.

Internal space makes airflow easier to secure, and most models support liquid CPU coolers with radiators.

Therefore, even high-end component sets—CPUs like Core i9 or Ryzen 9 and GPUs like the RTX 4080 or 4090—are well supported.

Thanks to strong expandability, future upgrades are straightforward, making mid-towers suitable for beginners and advanced users alike.

Full-tower cases

Full-tower cases are the largest PC cases, designed primarily for high-end users and professionals.

Height/depth are roughly 55–65 cm, and width is about 25–30 cm—approximately 10 cm larger than mid-tower cases.

For first-time builders, even a mid-tower may feel large; a full tower will feel notably larger in person.

These cases excel in expandability and cooling performance, supporting large numbers of storage drives and multiple graphics cards.

Airflow improvements and custom or AIO liquid cooling are easier to implement, accommodating overclocking and heavy workloads.

Full towers require more installation space, but they are highly advantageous for future upgrades and customization.

Motherboards beyond ATX, such as Extended ATX, are often supported.

This enables installation of more memory, storage, and expansion cards.

Accordingly, rather than typical builds, full towers suit heavy DIY PC users aiming to integrate many high-end components.

Mini-tower cases

Mini-tower cases are compact yet offer sufficient expandability.

They generally support smaller motherboards such as Micro ATX and Mini-ITX.

This size is very convenient for limited spaces or when the PC needs to be moved periodically.

They fit under desks or in narrow spots and are also appropriately sized for desktop placement without sacrificing work area.

While some CPU coolers and graphics cards may not match depending on the case and part dimensions, it is still just about possible to install high-performance components.

However, from this size class upward, the selection of truly high-end parts definitely narrows.

Therefore, it is important to consider whether the desired performance level aligns with the preferred case size.

Mini-towers generally support decent internal airflow and radiators for liquid cooling, so cooling performance is acceptable.

Assembly work may be a bit tighter, but there is enough space to avoid cramped airflow.

Recent mini-tower cases also emphasize design, satisfying users who value aesthetics in a compact PC case.

Slim cases

Slim cases are ideal for users who prioritize space saving.

As the name implies, they are narrow in width and easy to place on a desk or in confined areas.

They are generally designed for home and office use, making them suitable for everyday and business tasks.

This size is common among prebuilt office PCs.

Because internal space—especially width—is limited, a low-profile, top-flow air CPU cooler is required.

Although cooler performance is a step down, it is still possible to install a high-performance CPU with higher heat output.

However, the cooler load and fan RPM tend to be high, increasing noise, so it is not recommended for quiet builds.

Liquid CPU coolers are difficult to accommodate, and storage options are limited, so expandability is not high.

Graphics cards generally cannot be installed due to case width.

Even if installation were possible in some models, there are effectively no options suitable for smooth 3D gaming.

Thus, compared to mini-towers, slim cases impose considerably more constraints.

For DIY builds, unless there is a specific requirement for a slim form factor, this size is not an optimal choice.

For light tasks such as web browsing and video viewing, and where space saving is mandatory, a slim case may still be appropriate.

Small cases

Small cases are easy to place in tight spaces and are optimal when desk area is limited or when the PC footprint must be minimal.

However, standalone small cases for DIY are rare; they are more commonly seen as barebone kits like DeskMini, so available products are relatively few.

A barebone kit is a preconfigured set of core components.

It typically includes a motherboard and power supply, and sometimes a CPU and CPU cooler; memory, storage, and the OS are often not included.

Users select and install the remaining parts to build a customized PC easily.

Barebones are popular among those who want an easy DIY experience or a small form factor (SFF) PC.

Most small cases only accept compact CPU coolers, so CPU should be low-power (low-heat) or mobile-oriented models.

Graphics cards generally cannot be installed, so overall performance is quite limited.

Some cases support the VESA mount standard used for attaching to monitors or monitor arms.

This allows the case to be mounted behind a monitor, making it invisible from the front.

While space saving is a clear advantage, high-performance configurations are unrealistic.

Therefore, small cases suit scenarios where top-tier performance is unnecessary—such as web browsing, document creation, and video viewing—and where size takes priority over speed.

The author owns one DeskMini and uses it as a server-like device to run self-made programs on a schedule.

High performance and graphics capability are unnecessary for that role, and the compact size is ideal.

Cube cases

Conventional PC cases typically have similar height and depth with a narrower width, but cube cases have roughly equal dimensions on all sides, forming a near-cubic shape.

As the name implies, the focus is on shape, so actual size ranges from small to large.

Accordingly, support for large CPU coolers and graphics cards—and overall expandability—varies by model. Check specifications to confirm part fitment when selecting a cube case.

Horizontal desktop cases

Horizontal desktop cases are essentially slim cases placed on their side.

A common usage pattern is to place the monitor on top of the horizontally oriented PC.

Frankly, a slim case can also be placed horizontally, so the two are quite similar.

Care must be taken not to block intake/exhaust vents on the bottom surface.

Slim cases often include stabilizers to prevent tipping, so standing a horizontal desktop case upright may feel unstable.

Performance is broadly similar to slim cases; large CPU coolers and graphics cards are impractical.

Accordingly, these cases suit everyday and business-oriented light workloads.

Summary: For DIY PCs, mid-tower cases are the most practical

This article explained what case size implies and outlined the features of each PC case category.

Key points are summarized below.

Actual part counts and size limits vary by case model, so always check specifications when selecting components; the general tendencies above should help guide that process.

Among the various case types, mid-tower cases are the most popular, easy to assemble, and offer upgrade-friendly expandability.

That said, DIY PC building is about tailoring a system to individual goals. Choose a case size after understanding the characteristics of each category.

Basic knowledge about PC case brands is covered, along with how to choose from performance and compatibility perspectives.

≫ Related article: How to Choose a DIY PC Case [Performance / Features / Compatibility]

あわせて読みたい

PC Parts Estimation & Compatibility Check Tool

Automatically checks each component you need when selecting parts for a custom-built PC—perfect for beginners.