Methods, apparatus, systems and articles of manufacture to estimate ratings for media assets using social media are disclosed. An example method includes accessing media exposure data and social media activity data corresponding to a plurality of media assets in a media bundle, the media assets included in the media bundle having audience demographics that overlap with a first media asset, determining a first credibility factor for the first media asset and average exposure for social media activity count values for respective ones of the media assets in the media bundle based on the media exposure data and the social media activity data, and applying the first credibility factor to an average exposure per social media activity count value determined for the first media asset to estimate the ratings for the first media asset.