Methods and apparatus to collect impressions using media object characteristics are disclosed. An example apparatus includes an impressions monitor to receive a communication from a collector media object presented at a client device. The communication includes a first characteristic corresponding to the collector media object, and second characteristics respectively corresponding to a plurality of second media objects concurrently presented with the collector media object. The example apparatus further includes an attributor to associate demographic information with the first and second characteristics based on the first and second characteristics being received in the same communication from the client device.