← Insights  ·  October 2026 · 9 min read

How to Read Your AWS Bill: Cost Explorer in 20 Minutes

The most common thing we hear from the person who pays the bill is “I can’t tell what I’m paying for.” The invoice is a list of services. Cost Explorer is the tool that turns it into answers. Here is the 20-minute version, with the six views worth saving and the lines that confuse everyone.

Three places AWS shows you money

• The Bills page is the invoice: totals by service, after the month closes. Good for accounting, useless for finding waste.
• Cost Explorer is interactive: 13 months of history, daily or monthly granularity, filters and grouping, free to use in the console. This is where you start.
• Cost and Usage Reports (now called Data Exports) are every line item, hourly, delivered to S3 for spreadsheets and tooling. You want this eventually; you do not need it today.

If you have never opened Cost Explorer, enable it first from the Billing and Cost Management console. It can take up to 24 hours to populate, so turn it on now and do the rest tomorrow if you have to.

Minute 0–2: set the defaults

Date range: last three months. Granularity: monthly. Charge type: unblended costs, which matches your invoice. If you own Savings Plans or Reserved Instances, switch to amortized costs so an upfront payment is spread across the months it covers instead of landing on one day. Exclude credits and refunds when you want to see what usage actually costs.

Minute 2–15: the six views to save

Each of these is one change to the “group by” or “filter” controls. Save each one as a report so next month takes two minutes, not twenty.

1. Monthly cost by service, last six months

Group by Service. The top five services are usually 80% of the bill. Anything else is noise for now. Write the five down with their numbers; everything that follows is about those five.

2. Daily cost by service, last 14 days

Same grouping, granularity set to daily. Look at the weekends. If the line is flat seven days a week, your non-production environments never stop, and scheduling them is probably your largest single saving. A healthy chart dips on Saturday and Sunday.

3. Usage type, filtered to EC2-Other

Filter Service to EC2-Other, then group by Usage Type. This is the line that confuses everyone, and the view decodes it. You will see entries like these:

4. Instance type and purchase option, filtered to EC2-Instances

Filter Service to EC2-Instances and group by Instance Type. Previous-generation families (t2, m4, m5, r4) are candidates for a generation upgrade; see the Graviton math. Then change the grouping to Purchase Option. If almost everything says On-Demand and the workload has been running for months, you are paying full price for capacity you could commit to at a discount.

5. Linked account, or region

If you use AWS Organizations, group by Linked Account. If you do not, group by Region. Either way you are looking for the account or region you forgot about: the proof-of-concept from last year, the backup copy in a second region, the test account a contractor set up.

6. Tag

This view only works after you activate cost allocation tags in the Billing console (Environment, Team, and Application are the three worth having). Activation takes about 24 hours and only applies going forward, so do it today even if you cannot use it yet. Once it works, this is the view you will use every month, because it answers “what does this product cost?” in one click.

The lines that confuse everyone

• EC2-Other: see view 3. Storage, snapshots, NAT, and IPs, not instances.
• Data Transfer: traffic out to the internet is free for the first 100 GB a month and about $0.09 per GB after that up to 10 TB. Cross-zone traffic is separate and shows up under EC2-Other.
• Savings Plans for AWS Compute usage with negative numbers: that is the discount being applied. The positive line is the commitment you paid; the negatives are the on-demand charges it replaced. Amortized view makes this readable.
• Support: Business Support is a percentage of your usage (10% of the first $10,000 a month). If nobody has opened a ticket in a year, Developer Support may be enough.
• Tax: what it says, and the one line you cannot optimize.

Minute 15–20: two free alerts

1. A monthly cost budget in AWS Budgets, set to last month’s bill, emailing you at 80% of actual spend and at 100% of forecasted spend. Plain budget alerts are free.
2. Cost Anomaly Detection, one monitor across all services, alerting on anything that looks like more than about $50 a day of unexpected spend. Also free, and it catches the runaway Lambda or the forgotten GPU instance in a day instead of at month end.

What Cost Explorer still will not tell you

It will show you that EC2 costs $4,000 a month. It will not tell you that half of those instances average 4% CPU, that the Multi-AZ database is for a dev environment, or that the NAT gateway is carrying traffic that should go through a VPC endpoint for free. For that you need CloudWatch metrics, resource-level data (Cost Explorer keeps it for the last 14 days if you enable it), and someone to look at the architecture. That part is the review.

Written by Ruben Rivero, AWS Certified Solutions Architect – Professional. 12+ years running enterprise AWS environments.