Vmware CPU Sizing

Hi,

I have a current Vmware environment running on slightly older blades. My environment hosts around 100 virtual machines that have grown over a period of time.

I'm now looking to condense these vms down to a 1/3 or 1/4 with higher spec virtual machines. My current VMs aren't particularly CPU intensive.

I'll be going from hosts with 40 cores to newer hosts with marginally better CPUs with 20 cores.

Please advise how I can get my sizing right.

Thanks