That would be “4.00 decimeters”. People tend to skip decimeters entirely tbh, large things are measured in meters, small things in centimers, tiny things in millimeters. It is true that my desk is 8 decimeter deep and 24 decimeter wide, but it was listed as 2.4x0.8m in the store.

All deci- are rare actually. I sometimes encounter deciliters in recipes, but they’re just as likely to go for 10 centiliters or 0.1 liters.