Methods of and apparatus to estimate one or more volumes of one or more components of a fluid in a sample chamber of a downhole tool are described. An example method includes obtaining a sample chamber volume measurement, a flowline volume measurement and a supplemental volume measurement. The example method includes drawing the fluid into the sample chamber until the sample chamber is substantially full and measuring a characteristic of the fluid in the sample chamber at a first time to obtain a first characteristic measurement. The example method also includes adding a supplemental volume corresponding to the supplemental volume measurement to over-pressurize the sample chamber after measuring the characteristic at the first time and measuring the characteristic of the fluid in the sample chamber at a second time to obtain a second characteristic measurement. The second time is after the sample chamber is over-pressurized. In addition, the example method includes calculating a first volume of a first component of the one or more components of the fluid based on the first characteristic measurement, the second characteristic measurement, the sample chamber volume measurement, the flowline volume measurement and the supplemental volume measurement.