Izumo do 27000 T full for 248 x 38 x 7.5 m
Wasp do 41000 T full for 253 x 32 x 8 m
These are almost the same size, Izumo more large and 14000 t of difference !
Let's convert into feet.
Length:
Wasp - 844 ft.
Izumo- 814 ft.
Beam
Wasp - 106 ft.
Izumo- 110 ft.
Draft:
Wasp - 27 ft.
Izumo- 24.5 ft.
So, if you take a cube (which they are not), but if you apply the same to both it can work for comparative purposes you end up with:
Wasp = 844x106x27 = 2,415,528 ft. cubed
Izumo= 814x110x24.5= 2,193,730 ft. cubed
The Wasp is 221,798 ft. cubed larger. Which is approximately 10% in terms of volume. But then you look at the loadout, the fueling capability, etc and you can come up with the difference. I personally believe the Izumo is closer to 30,000 tons full load if they really load her out. The Wasp is 40,500 tons so in essence you have a ship that is 30 ft longer and 2.5 ft deeper that is 10,000 tons more. That works for me.