Plasmids transfer at highly variable rates which spread over 10 orders of magnitude. While rates have been measured for decades and it is known that the rates are affected by biotic and abiotic factors, it is unclear how and to what extent these factors determine the rates of transfer. We performed a meta-analysis of 1224 published transfer rates from 33 papers (filtered to 612 transfer rates) to assess this variation. Over three quarters of the variation can be predicted, with plasmid repression and media type (solid versus liquid) identified as general variables explaining the most variation. Of the host and plasmid identities, identity of the recipient bacterium explained the most variation, up to 34% in some models, and more than any other explanatory variable. These results emphasize the role of the recipient in determining the rate of transfer, and show an improved range of transfer values and their correlates that can be used in future when modeling plasmid persistence.