A transparent estimate
All reference input defaults are preserved. The starting rates are the reference’s static US East baseline, not a live price catalogue. Change the configuration and check the effective rates in the final step. Blank overrides retain that baseline; entering zero deliberately means a zero rate. Unsupported OS or database-engine rates require an override instead of silently producing a free instance. Region and database edition are recorded with a notice to verify the matching rate, because we do not invent regional or licensing multipliers.
The reference’s reserved-price factors are illustrative 0.75/0.70/0.65 for one year and 0.60/0.55/0.50 for three years, not verified AWS discounts. A supplied instance-hour override is the effective rate after your commitment or licence, so no additional discount is applied. Supplied RDS rates cover the entire deployment; baseline multi-AZ rates use the reference’s simplified 2× assumption. Verify actual engine, topology, storage and IOPS prices in the official AWS calculator.
Why your number may differ
Legacy reference allowances reproduce the original scenario: EC2/EBS zero, S3 USD6.70, Lambda about USD1.67 and RDS USD9.20. They are an illustration, not automatic eligibility. AWS’s current free-tier page describes credit-based new-customer plans. Use no allowances for a gross estimate or enter your verified account allowances and eligible monthly credit. Credit is limited to the estimated bill; the annual figure repeats this month’s assumptions and does not promise credits last twelve months.
We apply EC2 allowances once to combined instance usage, rather than repeating an account allowance per instance. Lambda GB-seconds = MB/1024 × billed milliseconds/1000 × invocations; durations round up to whole milliseconds. The two architectures have different baseline compute rates. GP3 IOPS beyond 3,000 are included at an illustrative USD0.005 per extra IOPS-month; override it for your region. Standard EBS, retrieval fees, minimum storage duration/object size, intelligent-tiering monitoring, RDS licences, Aurora I/O, CPU credits, data-transfer allowances shared with other services, taxes and support may need extra budget. Input transfer is recorded and assumed free. Rates and allowances must be verified against service pricing and Lambda pricing before spending decisions.