Build a full monthly EC2 bill from compute hours, attached EBS storage and data transfer out, and see what dominates.
An EC2 line item is really three meters: instance-hours, provisioned EBS capacity per GB-month, and internet egress per GB above the free allowance. EBS bills on what you provision rather than what you write, and inbound traffic is free, which is why the transfer term only counts data leaving the region. Compute usually looks like the whole bill until a chatty workload pushes egress past the allowance — splitting the three meters shows which one to attack first.
EC2 Monthly Cost
total = rate × instances × hours + EBS rate × GB × instances + egress rate × max(0, egress GB − free allowance).
total = rate × instances × hours + EBS rate × GB × instances + egress rate × max(0, egress GB − free allowance). An EC2 line item is really three meters: instance-hours, provisioned EBS capacity per GB-month, and internet egress per GB above the free allowance. EBS bills on what you provision rather than what you write, and inbound traffic is free, which is why the transfer term only counts data leaving the region.
Compute usually looks like the whole bill until a chatty workload pushes egress past the allowance — splitting the three meters shows which one to attack first.
This calculator takes 8 inputs: On-demand rate per instance-hour, Number of instances, Hours running per month, EBS volume size per instance, EBS price per GB-month, Data transferred out to the internet, Free egress allowance, Egress price per GB above the allowance. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
730 is 8760 ÷ 12, the true average month length. Using 720 (30 × 24) understates an always-on instance by about 1.4%, which matters once you multiply it across a large fleet.