# How do I add forecast values to a time series?

You can add forecast values to a raw time series in the series list, or after having applied some calculations to it.

### Add a forecast in the beginning of the document

To add a forecast to the raw time series, before any calculations are made, click on "Series list" in the analysis tree. Open the tab called "Forecasts" and click "Edit" next to the series you'd like to add a forecast to.

Please note that these forecasts will be added on the original frequency of the time series, even if the document uses another frequency.

### Add a forecast after calculations

To add the forecast after having applied some calculations to it, add the forecast as an analysis later in the analysis tree.

### Extend a series using Macrobond formula language

You can write a formula to extend a series, and then flag those values as forecast. This is good when you want to customize how the forecast values are generated. There are several formulas available for this, such as:

Extend(series, observation, number)
ExtendLastAsForecast(series)
ExtendLinear(series, observation, number)