Why coffee cup lids have a tiny second hole — almost everyone gets it wrong, do you?

You've seen it a hundred times, but have you ever really noticed? That second, tiny hole in your takeaway coffee lid isn't a mistake or just a steam vent.

February 04, 2026 / 09:44 IST
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Why Coffee Cup Lids Have a Tiny Second Hole
Why Coffee Cup Lids Have a Tiny Second Hole
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  • The second hole in coffee lids prevents spills by allowing air in.
  • It also lets steam escape, reducing pressure and making drinking safer
  • This design feature ensures a smooth, pleasant coffee-drinking experience

You've seen it a hundred times, but have you ever really noticed? That second, tiny hole in your takeaway coffee lid isn't a mistake or just a steam vent. It’s a clever piece of everyday engineering that saves you from messy—and even painful—spills.

According to a report from The Daily Mail, this small feature plays a vital role in how you enjoy your drink on the go. It’s the reason your coffee doesn’t bubble over or shoot out unpredictably when you take a sip while walking or driving.

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So, What Does It Really Do?

Think of it like this: when you drink, liquid needs to come out, but air needs to go in to take its place. If there’s only one hole (the one you sip from), the air has to fight its way past the stream of coffee. This struggle causes glugs, sudden spurts, and dangerous splashbacks. That hot coffee could easily burn your mouth or face.