Why Is There a Hole in the Middle of Plastic Stools? It's Not for Looks! Insiders Reveal the Real Function: 'It Would Be Impossible Without It'

Whether at community events, night market stalls, or street-side banquet setups, the vibrant and lightweight red plastic stool is undoubtedly the most familiar seating for people in Taiwan. Not only is it inexpensive and durable, but it can also be easily rinsed clean with water when dirty, and when not in use, multiple stools can be neatly stacked for storage—making it extremely convenient.

But why does the center of the seat on these plastic chairs always have a round hole? A netizen once asked this question on a social media platform, sparking responses from many insiders who revealed that this seemingly insignificant design actually embodies clever insights from atmospheric physics and manufacturing technology.

Only after decades of sitting on them did we realize! Why do the 'red plastic stools' at banquet tables have a hole in the middle?

A user posted a photo of a traditional red plastic stool in the Facebook group 'What Are You Doing Now?' and asked, 'I've been sitting on this kind of plastic chair for decades, but I still don't know what the hole in the middle is for.' The post immediately sparked heated discussion.

Regarding this mysterious hole, many netizens jokingly said things like 'for inserting umbrellas,' 'venting gas when passing gas,' or 'using it as a megaphone.'

However, many knowledgeable users soon stepped in with real answers, pointing out that the most important function of this hole is 'preventing airtight suction when stacked.' Numerous commenters noted, 'When stacked, the hole balances air pressure so they’re easier to separate,' 'It allows air to escape when stacking and re-enter when lifting, preventing vacuum lock,' 'Without the hole, they’d stick together due to vacuum pressure and be impossible to pull apart,' and 'The hole makes it easier to lift stacked chairs.'

The physical principle is similar to the famous 'Magdeburg hemispheres experiment.' If the plastic stool had no hole in the seat, when multiple stools are tightly stacked, a near-sealed or semi-vacuum state forms between the upper and lower layers. Atmospheric pressure would then firmly adhere the stools together, requiring tremendous force to separate them. With the central round hole, air can escape smoothly during stacking, and when pulling apart, air quickly flows back in to equalize pressure—making storage neater and retrieval effortless.

One hole, multiple uses! Revealing the 'four hidden design secrets' of the red plastic stool

Beyond pressure balancing and preventing vacuum adhesion, other benefits were also mentioned. For example, the hole helps balance stress and makes disassembly easier—allowing air to vent during stacking and flow in during removal, eliminating vacuum effects caused by pressure differences, so stacked chairs can be easily separated. It also makes it easier to grip with fingers—the size of the hole is just right for an adult finger to hook into, enabling one person to lift multiple chairs at once with one hand, greatly improving搬运 efficiency.

Some netizens also said the hole facilitates mold release during manufacturing. A central opening helps the mold release smoothly and allows gases to escape, increasing factory production yield. Additionally, it saves plastic material and enhances structural stability. A circular opening distributes weight more evenly across the seat than a square one, reducing the likelihood of cracks, while simultaneously cutting down on plastic costs.