Us Brits usually need a big wake-up call in the morning, which is why we often reach for a coffee.

We all need that little pick-me-up to help us feel alert before work, but one man has revealed something quite mindblowing. If you usually pick up your cuppa at Costa, he said it’s probably best to avoid buying a large cup.

This is because he claims it’s a waste of money due to the portion people are handed. Known as rightguysreview on TikTok, he shared the ultimate Costa life hack.

In the video, he said: “I got myself a large one and, apparently, a large one actually fits inside a medium cup. Are Costa ripping us off?”

You then see him pour the large coffee into an empty medium cup, and it fits perfectly. The coffee conundrum has left people totally gobsmacked, as he concluded the clip by saying: “Yes, they are.”

After completing the experiment, he said Costa are “naughty”, and advised people to “always buy a medium”. Social media users had a lot to say after he shared the trick.

One person said: “Read this a couple of years ago and stick to a medium now.” Another wrote: “They never fill the cups, same at Starbucks.”

A third replied: “I will never understand why they charge more for a large tea. It’s literally just extra water.”

Meanwhile, a fourth decided to see the funny side, adding: “But then a medium will fit into a small.”

Not everyone was convinced by the tip though, as they noted something pretty important. Some said the price isn’t just about the cup size.

In the comments, a few people pointed out that – when people pay more for a large – they’re likely to be paying for extra coffee. They said people hand over the cash for the amount of shots they want, as oppposed to the measurement of liquid.

One person said: “The large has two shots of coffee in as well.” Another chimed in with: “A large will have more shots.”

A third also wrote: “You don’t pay for the water – it’s the coffee shots.”

Costa has been approached for comment.