Currently, we do not support creating goal lines or horizontal annotations in Amplitude. If you are interested in functionality like this, please submit a feature request.
In the meantime, you can “hack” custom formulas to create horizontal annotations and set “targets” for various metrics.
In this demo example, I’ve multiplied a metric by 0, then added my target value of 120,000. You can rename the labels and y-axis etc. for a more legible chart.
Another “hack” is to plot two differently scaled metrics on the same axis. In this example, % Active and Uniques are on totally different scales making the content illegible. You can scale a metric up by multiplying it by a factor of 10 (in this case 100,000) so the metrics appear on the same scale. If doing this, it’s recommended that you indicate the metric has been scaled up by renaming it as I’ve done here.