AWS cost engineering notes
What we learn running AWS cost pipelines in production. Billing data, Kubernetes, networking, storage, and whatever else the bill throws up. Every figure is checked against AWS documentation and linked, including the parts that do not work.
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API Gateway: REST vs HTTP API cost (2026)
API Gateway HTTP APIs are 3.5x cheaper per request until the payload passes 1.5 MB, where the 512 KB metering increment flips it.
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When a cheap S3 storage class costs more (2026)
Minimum durations, the 128 KB rounding rule and the 40 KB Glacier overhead billed partly at S3 Standard rate.
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Updated Security / Network cost / Governance
AWS WAF pricing and what it costs (2026)
Ten million requests cost $6. The nineteen WAF rules inspecting them cost $19. Plus two overage meters that live in a footnote.
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Updated Network cost / VPC
What a NAT Gateway actually costs (2026)
The two meters a NAT Gateway bills, why one zonal gateway across three AZs costs more, and what regional mode changed in 2025.
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Cut Amazon Bedrock inference cost (2026)
Bedrock batch inference is 50% off, cache reads 75% off, and AWS states the two cannot be combined. Plus the caching failure that raises no error.
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Updated Bedrock / AI cost / CUR 2.0 / Cost allocation
Amazon Bedrock cost per team (2026)
Bedrock does not split by team by default. IAM principal cost allocation and application inference profiles: what each answers, and why CloudWatch cannot.
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Updated EKS / Kubernetes / FinOps
EKS Auto Mode: the third bill (2026)
EKS Auto Mode adds a management fee that varies by instance type, on top of EC2 and the control plane. And split cost allocation does not divide it.
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Updated Governance / Budgets / FinOps
AWS Budgets vs Cost Anomaly Detection (2026)
They catch different failures, and only Budgets sees AWS Marketplace charges. Detection lags, monitor types, and what to run.
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How AWS credits actually apply (2026)
Soonest to expire first, largest charge first, biggest account first. Plus what credits will not cover, including Marketplace.
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Updated EKS / Kubernetes / FinOps
EKS extended support: $0.10 to $0.60 (2026)
EKS extended support is six times the control plane rate, on a published date, enabled by default. Once a cluster is in it you cannot turn it off.
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Updated Cost allocation / Cost categories / FinOps
AWS Cost Categories: split charge limits (2026)
Cost categories apply retroactively to the start of the month. Split charge results never reach the CUR or Cost Explorer.
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Updated Organizations / FinOps / Cost allocation
Does consolidated billing save money? (2026)
AWS's worked example puts consolidated billing's volume tiering at about 4%. Commitment sharing is worth far more than that.
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Updated Network cost / VPC / S3
VPC endpoint cost: gateway vs interface (2026)
VPC gateway endpoints for S3 and DynamoDB carry no charge. Three documented ways one silently stops covering your traffic.
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Updated Security / Governance / FinOps
Secrets Manager vs Parameter Store (2026)
AWS prices 1,500 secrets at $604.50 a month in Secrets Manager. Standard Parameter Store parameters are free. Plus a tier change you cannot undo.
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AWS Cost Optimization Hub: the gaps (2026)
EKS spend counts toward Cost Optimization Hub's efficiency score but generates no recommendations, so a wasteful cluster raises the number.
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RDS extended support: priced per vCPU (2026)
RDS extended support scales with instance size, unlike EKS, and runs three years. Disabling it on a lapsed database upgrades the engine immediately.
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Updated Lambda / Serverless / FinOps
Do Lambda cold starts cost money? (2026)
Since 1 August 2025 every Lambda is billed for INIT, the cold start phase. What changed, how to measure it, what does not fix it.
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Updated Network cost / VPC / Flow logs
What VPC Flow Logs actually cost (2026)
VPC Flow Logs bill the tiered Vended Logs meter. The aggregation interval AWS overrides on Nitro, and records you pay for twice.
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Updated Network cost / DNS / FinOps
What Route 53 actually costs (2026)
Route 53 hosted zones are not prorated, alias queries to AWS services are free, and a Resolver endpoint is about $182 a month.
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Updated Network cost / VPC / EC2
Elastic IP and public IPv4 pricing (2026)
A public IPv4 is $0.005 an hour, and idle addresses cost exactly the same as in-use ones. Plus AWS's formula for whether a NAT Gateway is cheaper.
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Updated ECS / SCAD / CUR 2.0 / Kubernetes
ECS split cost allocation data vs EKS (2026)
SCAD covers ECS tasks too, but ECS gets no service-generated tags and no GPU splitting. Plus the row count formula.
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EC2 Capacity Reservations: unused cost (2026)
An EC2 Capacity Reservation bills at full On-Demand whether used or not, and the idle half arrives as UnusedBox. Plus who pays when it is shared.
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Updated EKS / Kubernetes / Observability
Container Insights pricing on EKS (2026)
Container Insights with enhanced observability is $51.75 a month on AWS's 10-node example. Turning it off costs $101.73.
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Query your CUR in Athena, no crawler (2026)
Athena partition projection computes partitions from table properties. The config, and six ways it returns zero rows not an error.
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Updated DynamoDB / Serverless / FinOps
DynamoDB on-demand vs provisioned (2026)
AWS publishes the DynamoDB break-even: on-demand costs less below 35% utilisation. Plus the console switch that deletes your auto scaling.
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Are AWS Glue crawlers free? (2026)
No. Glue crawlers bill $0.44 per DPU-hour with a 10-minute minimum per crawl, so an hourly schedule costs about $1,285 a year.
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Updated Cost allocation / CUR 2.0 / Tagging
Why cost allocation tags show up empty (2026)
Tagging a resource is not activating cost allocation tags. The two 24-hour delays, what a backfill can recover, and the CUR 2.0 key change.
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Updated Savings Plans / FinOps / Cost allocation
Savings Plans: coverage vs utilization (2026)
Savings Plans coverage and utilization move in opposite directions. What each low value means, and the documented order AWS applies discounts in.
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Does a stopped EC2 instance cost money? (2026)
A stopped EC2 instance bills no compute. The EBS volume, any Elastic IP and any Savings Plan under it do, and hibernating costs more.
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Governance / Logging / FinOps
AWS CloudTrail pricing and costs (2026)
CloudTrail's first copy of management events is free; the second costs $2.00 per 100,000, twenty times the rate of S3 data events.
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Updated EKS / Kubernetes / Discovery
Find every Kubernetes cluster in AWS (2026)
eks list-clusters misses two of three Kubernetes populations. The flag for connected GKE and AKS, the EC2 tag scan, and the dedup.
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AWS KMS key pricing at scale (2026)
A rotated key costs $3 a month, not $1. And S3 Bucket Keys cut KMS request charges by up to 99% with no code change.
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What an EBS snapshot actually costs (2026)
Archiving converts an incremental EBS snapshot to a full one, so the cheap tier can bill 10x more. Plus why deleting frees nothing.
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Updated Cost Explorer / CUR 2.0 / FinOps
Why Cost Explorer and your CUR differ (2026)
Same dataset, three totals. The six documented causes, which number you owe, and what Cost Explorer charges per request.
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Updated Security / Network cost / Governance
GuardDuty bills flow logs you never made (2026)
GuardDuty analyses an independent duplicate stream of VPC Flow Logs, so deleting your own changes nothing. Plus the per-Region trial trap.
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Updated CUR 2.0 / Cost allocation / FinOps
Amortized vs unblended cost in AWS (2026)
Five CUR cost columns, one right answer per question. When to use amortized, when unblended, and why blended cost is never the answer.
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Updated EKS / SCAD / Kubernetes
EKS split cost allocation data (2026)
The three measurement options in EKS split cost allocation data, why the choice matters, and the Fargate-derived 9:1 CPU-to-memory weighting.
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Updated Governance / FinOps / Compliance
What AWS Config actually costs (2026)
You are billed per configuration item, and AWS confirms one is recorded even when no resource is created. Churn is the driver.
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Updated Network cost / VPC / CUR 2.0
What cross-AZ data transfer costs (2026)
Cross-AZ transfer is $0.01 per GB each direction, so $0.02 a round trip. What is free, what a public IP costs, and the usage type that changed in 2025.
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Limit what one Athena query can scan (2026)
Athena's per-query limit cancels; the per-workgroup limit only alerts. Cancelled queries are still billed and leave debris.
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Updated Logging / Governance / FinOps
What CloudWatch Logs actually cost (2026)
The CloudWatch Logs Infrequent Access class halves ingestion only, removes metric filters and alarms, and can never be changed after creation.
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CUR 2.0 vs FOCUS: only one costs pods (2026)
A field-level comparison from the AWS column dictionaries: what CUR 2.0 has that FOCUS does not, and four gotchas.
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Updated Network cost / VPC / FinOps
Transit Gateway pricing and costs (2026)
Transit Gateway attachment hours land on the VPC owner, not the gateway owner, and three types bill three different accounts.
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Updated Cost Explorer / Network cost / CUR 2.0
What is EC2 - Other in Cost Explorer? (2026)
EC2 - Other is not a service. What the bucket holds, the usage types that break it down, and why it never appears on your invoice.
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Updated Network cost / Load balancing / EC2
ALB pricing: what an LCU actually is (2026)
An ALB LCU has four dimensions and AWS charges only for the largest. Which one is yours, and why the eleventh listener rule starts a meter.