Stowage Rate Calculations

Hello All,

I’m currently doing a project regarding ship design and have faced an issue regarding stowage rate (m^3/tonnes)
The range is from 1.4<range<1.5. However, my calculation is 1.60.
Are there any reasons to substantiate why it’s over?
I’ve tried looking around but there aren’t any proper load calculation resources online, so i hope experienced personnel can provide some suggestion please!