AWS EC2 Cost Calculator (Monthly Pricing Estimator)

How to get your inputs

• Instances: use average running instances from billing (instance-hours / monthly hours).
• Hourly rate: use a blended $/hour if you mix on-demand, Savings Plans, or RIs.
• Schedule: hours/day and days/month should reflect real uptime windows.
• Sources: Cost and Usage Report, instance-hours metrics, or inventory snapshots.

Result interpretation

• If the estimate is far from your bill, check the blended rate and instance-hours first.
• Separate baseline vs bursty workloads to avoid mixing average and peak assumptions.

Common mistakes

• Using peak instance count as baseline.
• Applying both utilization and reduced hours/day for the same schedule.
• Forgetting storage, transfer, and load balancer line items.

Advanced inputs to capture

• Model instance count by family and uptime schedule.
• Use a blended $/hour if you mix purchase options.
• Add EBS volumes and snapshots as separate line items.
• Include network transfer out or cross-AZ traffic separately.

Scenario planning

Validate after changes

• Compare instance-hours and effective $/hour to billing line items.
• Check average instance count in metrics or inventory data.
• Review baseline vs peak deltas so autoscaling risk is visible in budget reviews.

Accuracy checklist

• Use measured instance-hours, not provisioned capacity.
• Use blended $/hour that matches your purchase mix in billing.
• Keep compute, EBS, transfer, and load balancer as separate line items.
• Recheck assumptions after instance family or commitment changes.

Purchase mix worksheet

• Baseline steady capacity: map to RI or Savings Plans candidates.
• Burst capacity: keep as on-demand unless burst is predictable.
• Interruptible workloads: model spot separately with interruption risk.
• Recalculate blended $/hour whenever commitment coverage changes.

Failure patterns

• Using list prices while finance tracks effective blended cost.
• Applying the same uptime schedule to prod and dev/test environments.
• Hiding autoscaling peaks inside monthly averages.
• Treating compute estimate as total stack cost without EBS or transfer.

Next steps