Starbucks has been slammed with a lawsuit in California that alleges that the chain underfills their latte cups to save millions of dollars.

The news could be enough to prompt consumers to crack open the lids of their Starbucks Grande-sized lattes to see if they've been shortchanged.

Filed in a California federal court this week by Siera Strumlauf and Benjamin Robles,that Starbucks lattes are “uniformly underfilled pursuant to a standardized recipe,” reported CBS Los Angeles.

To support their claim, attorneys for the plaintiffs bought and measured Grande lattes in several states and claim that each grande latte was underfilled by approximately 25 per cent.

Grande cups are supposed to hold 16 fluid ounces and are Starbucks' version of medium size.

According to the suit, baristas follow a standardized recipe which details measurements for nearly every step.

To finish the latte, baristas are instructed to pour steamed milk into the espresso, then top the beverage with a quarter-inch of milk foam, leaving at least a quarter-inch of space below the rim.

The suit alleges that underfilled cups save “countless of millions of dollars in the cost of goods sold,” shortchanging customers and benefitting the company.

It's the latest lawsuit filed against the coffee giant. Last year, the chain was slapped with two separate suits from customers alleging that they were served drinks which contained industrial-strength cleaning products.

The plaintiffs in California, meanwhile, are now seeking to have their suit certified as class action. The suit alleges multiple counts, including fraud, breach of express warranty, and breach of the implied warranty of merchantability.