Located in the campaign summary on the campaign create page, the traffic reach is a new feature we added to quickly show how much traffic you are discarding with your current targeting selection.

It is calculated from historical data taking into consideration the carrier, traffic type, campaign reach, network, device, user freshness and advanced targeting with 100% of the traffic being that maximum amount of traffic for the given format and geo. This does not take into account your current bid. Even though you're targeting 100% of the traffic does not mean you will receive 100% of the traffic.

Because we only look at recent data, it is normal that some countries may be lacking Insufficient data. This does not mean that you will not receive traffic. When targeting countries like these will very low volumes we always recommend avoiding narrow targeting to ensure you receive enough volumes.