AWS Cost Forecast & Rightsizer
Forecast AWS spend and calculate savings from Savings Plans and Reserved Instances. Enter values for instant results with step-by-step formulas.
Worked Examples
Example 1: Startup Growth
Problem:$10k/mo, 5% MoM Growth, 1yr Partial Upfront (30% off)
Solution:Forecast On-Demand: ~$159k. With SP: ~$125k.
Result:$34k Annual Savings
Example 2: Stable Enterprise
Problem:$50k/mo, 0% Growth, 3yr All Upfront (55% off)
Solution:Forecast OD: $600k. With SP: $270k.
Result:$330k Annual Savings
Frequently Asked Questions
Does this forecast Storage (S3) costs?
No, AWS Cost Forecast & Rightsizer focuses on Compute (EC2/Fargate/Lambda) where Savings Plans apply. S3 has its own tiering logic (Intelligent Tiering).
How accurate is the forecast?
It uses a simple compound monthly growth rate (MoM). Real cloud spend is often spiky. Use this for directional budgeting, not exact accounting.
How do I forecast revenue?
Bottom-up forecasting multiplies expected units sold by price. Top-down starts with market size and estimates market share. For existing businesses, use historical growth rates with adjustments. For SaaS: Forecast MRR = Current MRR + New MRR - Churned MRR + Expansion MRR. Always model best, expected, and worst case scenarios.
How do I calculate customer acquisition cost (CAC)?
CAC = Total Sales and Marketing Expenses / Number of New Customers Acquired in that period. Include all related costs: advertising, salaries, tools, commissions, and overhead. CAC payback period = CAC / Monthly Gross Margin per Customer. A payback period under 12 months is generally healthy for SaaS businesses.