Break down your costs

This guide reports a month's costs per service and per day, narrows a report to one service or region, and adds how much of each resource type you used.

Before you beginCopy Anchor Link

Sign in with the CLI, get a token for the API, or create the Python client.

1. Choose the period and granularityCopy Anchor Link

A report covers a period from start up to, but not including, end, and splits it into hourly, daily or monthly rows. A period can be up to 366 days long. Prefer daily or monthly for long periods, because hourly rows make large reports.

2. Group by what you want to compareCopy Anchor Link

group_by splits each row into groups. Group by any of service, region, usage_type, project_id and resource_id. Grouping by resource_id shows what each server, volume and image cost.

This request reports September's costs per service, per day:

openstack cost report create \
  --start 2026-09-01 \
  --end 2026-10-01 \
  --granularity daily \
  --group-by service \
  --metric cost \
  --detail

--detail adds the per-group rows to the CLI's table. The API returns one entry per day, each with a total and a group per service:

{
  "as_of": "2026-10-07T15:12:40Z",
  "currency": "USD",
  "pricing_version": "legacy-usd-21c6b51",
  "group_definitions": ["service"],
  "regions": [{"name": "ca-ymq-1", "data_through": "2026-10-07T14:00:00Z"}],
  "results_by_time": [
    {
      "time_period": {"start": "2026-09-01T00:00:00Z", "end": "2026-09-02T00:00:00Z"},
      "estimated": true,
      "total": {"cost": {"amount": "35.912000000000", "unit": "USD"}},
      "groups": [
        {"keys": ["compute"], "metrics": {"cost": {"amount": "31.104000000000", "unit": "USD"}}},
        {"keys": ["volume"], "metrics": {"cost": {"amount": "4.808000000000", "unit": "USD"}}}
      ]
    }
  ]
}

The keys of each group follow the order of group_definitions. The response continues with an entry for every day of September.

3. Filter what countsCopy Anchor Link

Filters narrow a report to some of your spending. A filter with several values matches any of them, and different filters must all match.

On the CLI, repeat an option to give several values. In the API, leave a filter out to count everything. An empty list matches nothing.

4. Add usage quantitiesCopy Anchor Link

To see how much you used as well as what it cost, add the usage_quantity metric. Hours and GiB-hours cannot be added together, so this metric needs grouping by usage_type:

openstack cost report create \
  --start 2026-09-01 \
  --end 2026-10-01 \
  --granularity monthly \
  --group-by usage_type \
  --metric cost \
  --metric usage_quantity \
  --detail

Each group then has a usage_quantity in Hours or GiB-Hours, and each row has usage_by_unit totals.

VerifyCopy Anchor Link

Add up the daily totals of a month and compare them with a monthly report for the same month. They are equal, because Cost Explorer counts each minute in exactly one row. If the most recent rows look low, check data_through: usage after that time is not counted yet.

Next stepsCopy Anchor Link

• Forecast your spending for the rest of the month.
• Get alerted before you overspend with Budgets.
• Look up every field in the API reference.