How to Read Your AWS Bill: A Plain-English Decoder for Usage Types

Your AWS bill says you spent $47 last month. On what, exactly?

The Bills page groups charges by service, which helps a little. But the real answer hides in usage types: cryptic codes like USW2-NatGateway-Hours or BoxUsage:t3.micro. Once you can read them, most "mystery" charges explain themselves in about five minutes.

This post is a decoder. No prior billing knowledge needed.

Step 1: Show your costs by usage type

The console's Bills page is too coarse. Use Cost Explorer instead (viewing it in the console is free):

1. Open Billing and Cost Management → Cost Explorer.
2. Set the date range to the last 3 months and granularity to Monthly.
3. Under Group by, choose Usage type.

You now get a chart and table of every usage type, sorted by cost. Three months lets you spot what's growing, not just what's big.

Tip: If one service dominates, add a Service filter (for example, EC2-Other) and keep grouping by usage type. EC2-Other is a common hiding place for NAT Gateway, EBS, and data transfer charges.

Step 2: Understand the anatomy of a usage type

Most usage types follow this pattern:

[region code]-[what you're charged for]:[detail] 

For example:

• USW2-NatGateway-Hours → US West (Oregon) · NAT Gateway · hours it existed
• APN1-BoxUsage:t3.micro → Tokyo · EC2 instance hours · instance type t3.micro
• EUC1-EBS:VolumeUsage.gp3 → Frankfurt · EBS storage · gp3 volumes

Region codes you'll see most

Two quirks worth knowing:

• US East (N. Virginia) often has no prefix at all. For many services, a charge there shows up as plain BoxUsage:t3.micro or TimedStorage-ByteHrs instead of USE1-.... If a usage type has no region code, N. Virginia is the usual suspect.
• Two region codes mean data moved between regions. USE2-USW2-AWS-Out-Bytes is data sent from Ohio to Oregon.

Step 3: Decode the usual suspects

These are the usage types small accounts run into most often. Region prefixes are left off for readability.

Compute and databases

Storage

Networking (where surprises usually live)

Monitoring

Notice the pattern: anything ending in Hours usually means "you pay while it exists." Those are the first lines to check when nobody is using your app.

Step 4: Turn a line item into an action

Once you've found your top 3 usage types, this table covers the most common fixes:

Bonus: the same view from the CLI

If you prefer the terminal, this prints last month's cost by usage type:

aws ce get-cost-and-usage \ --time-period Start=2026-10-01,End=2026-11-01 \ --granularity MONTHLY \ --metrics UnblendedCost \ --group-by Type=DIMENSION,Key=USAGE_TYPE \ --query "ResultsByTime[0].Groups[?to_number(Metrics.UnblendedCost.Amount) > \`0.01\`].[Keys[0], Metrics.UnblendedCost.Amount]" \ --output text | sort -t$'\t' -k2 -gr | head -20 

Change the dates to the month you want. One heads-up: unlike the console, Cost Explorer API calls cost $0.01 per request. Fine for occasional checks, but don't put it in a loop that runs every minute.

Wrapping up

Your AWS bill stops being scary once you can read it:

1. Open Cost Explorer and group by usage type over 3 months.
2. Read each code as region + what + detail. No prefix usually means N. Virginia.
3. Look hardest at anything billed in Hours. That's what you pay for just by existing.

Do this once a month, and surprise charges become rare.

If you want this alongside a full setup routine, I wrote a short PDF guide: a 30-minute action plan (MFA, budget alerts, anomaly detection, an all-regions sweep), copy-paste CLI commands, and a 10-minute monthly checklist. It's $9 on Gumroad: Stop AWS Bill Shock. You don't need it to use anything in this post.

Previous post: 5 Reasons Your AWS Bill Keeps Growing (Even When Nobody Uses Your App)

Sources (checked November 2026)

• AWS Region billing codes
• Amazon S3: Understanding your AWS billing and usage reports (US East prefix omitted)
• Amazon VPC pricing
• AWS Cost Explorer pricing