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AWS Pricing Models

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AWS Pricing Models

Price exercises in this note use hypothetical us-east-1 (US East, N. Virginia) rates for study on 2026-10-12, unless explicitly identified as a dated published fee. They are assumptions, not current tariffs; exclusions remain material.

Choose a purchasing model after measuring demand and failure tolerance. A discount does not remove storage, networking, support, tax or licensing costs.

Purchasing choices

ModelSuitable workloadMain constraint
On-DemandNew, variable or short-lived demandNo long-term discount commitment
SpotRestartable batch, distributed workers and flexible capacityCapacity can be interrupted; checkpoint and diversify
Reserved InstancesCompatible steady usage in a service offering reservationsScope, term, exchange and capacity rules vary by service
Savings PlansA predictable eligible hourly spend floorUnused hourly commitment is still payable
Capacity ReservationsEC2 capacity availability requirementsCapacity reservation is distinct from a discount

EC2 per-second billing has a 60-second minimum for supported products, including eligible Windows Server and SQL Server instances. Check the selected AMI/OS/license and product pricing; do not assume every marketplace license follows one rule.

Worked comparison

Assume 20 instances run for a 30-day month (720 hours), with an illustrative On-Demand rate of $0.192/instance-hour and a discounted rate of $0.127/instance-hour:

  • On-Demand: 20 × 720 × $0.192 = $2,764.80.
  • Discounted usage: 20 × 720 × $0.127 = $1,828.80.
  • Difference: $936.00, or about 33.9%.

These are assumed rates, not an AWS quote. They exclude upfront payments, unused commitments, storage and transfer. Compare effective total cost over the commitment term rather than discount percentage alone.

Free Tier cohorts

Accounts created before July 15, 2025 follow the legacy Free Tier rules. Newer accounts use the credit-based experience: up to $200 in credits, a free plan lasting up to six months, and credit expiration rules distinct from the plan duration. Paid-plan and Organizations eligibility matter; creating member accounts is not a reliable way to multiply benefits.

Decision exercise

Estimate a workload’s hourly minimum, peak and idle hours. Price three options in AWS Pricing Calculator, keeping the same Region, architecture and licenses. Reject a commitment that exceeds the post-rightsizing baseline.

Payment options and interruption trade-offs

Payment optionCash timingComparison method
No UpfrontRecurring commitment chargesSum all committed charges over the term
Partial UpfrontAn initial payment plus recurring chargesAdd both; the upfront fraction is offering-specific
All UpfrontTerm payment at purchaseDivide total by term hours for effective cost, then account for unused hours

Payment choice does not change an RI’s matching attributes or create Savings Plans capacity. Discount ceilings are not a quote for a selected configuration. Compare term, flexibility, financing and likelihood of using the benefit.

Spot pools are defined by instance type and AZ. Diversify compatible pools and use capacity-aware allocation rather than chasing one cheapest pool. Checkpoint progress and make workers restartable. A Spot interruption notice is best-effort; hibernation can begin without the normal two-minute lead. Defined-duration Spot blocks are retired, not a current way to buy interruption-free work.

Second worked scenario: mixed workers

For an illustrative us-east-1 exercise evaluated on 2026-10-12, assume four baseline workers at $0.10/hour for 720 hours and 20 additional workers for 80 hours. Assume an available Spot rate of $0.03/hour:

all On-Demand = (4 × 720 + 20 × 80) × $0.10 = $448
mixed         = 4 × 720 × $0.10 + 20 × 80 × $0.03 = $336
gross difference = $112

These are hypothetical rates, not a quote or a guaranteed Spot discount. Add retry/checkpoint work, storage and transfer before claiming net savings. If deadline-critical workers cannot recover from interruption, keep sufficient non-Spot capacity.

Traffic and quota checks

Price both direction and service path: same-AZ exceptions, cross-AZ peering, inter-Region replication, NAT processing and internet delivery differ. Quotas frequently use vCPUs and instance categories per Region rather than an immutable 20-instance allowance. Verify quota headroom before committing to a launch topology.

References

See Savings Plans and Reserved Instances.

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