Size an Azure VM down to the vCPU and memory it actually needs from observed peaks plus a headroom target.
Right-sizing converts an observed peak into an absolute resource demand, then divides by the utilisation you are willing to run at to get the size you need. Because Azure sizes come in fixed vCPU steps the answer is rounded up to the next step, and the memory-per-vCPU ratio of the family can force a larger size than CPU alone would. Averages hide spikes, so sizing on the 95th percentile with explicit headroom is the difference between a saving and an outage; validate the projected price against the Azure pricing calculator because cost does not always scale linearly with vCPU across families.
Azure VM Right-Sizing
required vCPU = current vCPU × peak CPU% ÷ target utilisation%, rounded up to the next Azure size; memory is checked the same way against the family's GiB-per-vCPU ratio.
required vCPU = current vCPU × peak CPU% ÷ target utilisation%, rounded up to the next Azure size; memory is checked the same way against the family's GiB-per-vCPU ratio. Right-sizing converts an observed peak into an absolute resource demand, then divides by the utilisation you are willing to run at to get the size you need. Because Azure sizes come in fixed vCPU steps the answer is rounded up to the next step, and the memory-per-vCPU ratio of the family can force a larger size than CPU alone would.
Averages hide spikes, so sizing on the 95th percentile with explicit headroom is the difference between a saving and an outage; validate the projected price against the Azure pricing calculator because cost does not always scale linearly with vCPU across families.
This calculator takes 7 inputs: Current vCPUs, Current memory, Observed peak CPU, Observed peak memory, Target peak utilisation, Current monthly cost per VM, VMs in this role. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.