Rocnas guide to recommended sizing of their anchors.
Upsizing a couple of weights is not necessary in our opinion but if you do make sure you find out how physically big these anchors are and if it will fit your boat.
If you're an offshore cruiser going up one size can be good for the peace of mind but again watch the physical size.
At the smaller lightweight race boat end you possibly can go down a size if you so desire.
The Guide is here - will open in a new window.