> ## Documentation Index
> Fetch the complete documentation index at: https://docs.costgraph.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Forecast

> What CostGraph's month-end forecast means, and how much history it needs

The forecast estimates what you'll spend by the end of the current calendar
month, in UTC, on all your spend or a filtered slice of it. Budgets use the
same forecast over their own period.

Read it with `GET /api/v1/tenant/cost/forecast` in the
[CostGraph API](/api-reference/costgraph/introduction). It takes the same
`layer` and `filter` parameters as cost queries, and works with an API key
that has the `focus:read` scope.

## The point and the range

The forecast returns one number and a range around it:

* `point` is the best estimate of month-end spend: what you have already spent,
  plus charges already known for the rest of the month, plus a model of your
  usage for the remaining days.
* `lo` and `hi` bound an 80% range. Month-end spend lands inside it about four
  months out of five.

`actual` is spend so far, `knownFuture` is charges already scheduled, and
`modelled` is the estimate for the remaining days. The forecast is of gross
spend, before credits.

## How it forecasts

`method` says which model produced the forecast:

* `regression` follows your recent trend and weekday pattern. CostGraph uses it
  once there are at least 14 days of history.
* `pace` projects your average daily spend. CostGraph uses it with 7 to 13 days
  of history.

## Minimum history

The forecast needs at least 7 days of spend history. With less, `point`, `lo`,
and `hi` are empty and `reason` says why.

## Currency

The forecast is in the currency most of the spend in scope is billed in. Spend
in other currencies is listed in `excludedCurrencies` and left out. Filter by
currency to forecast each one separately.


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