The Tax Base under the FairTax
Under the FairTax, all consumption of new goods and services (except tuition for education) is taxed at the same uniform rate.
The Bureau of Economic Analysis (BEA) keeps data on aggregate national personal consumption expenditures (PCE) as part of its National Income and Product Accounts (NIPA). If you are curious you can see how the BEA defines Personal Consumption Expenditures.
For 2003, the total PCE was $7709.9 billion dollars, of which $200.4 billion was for education and research. So the PCE contribution to the FairTax tax base is $7709.9 - $200.4 = $7509.5 billion.
The FairTax also taxes government consumption. The BEA keeps data on government consumption as well. For 2003, government consumption was $1,736.7 billion dollars.
So the total FairTax tax base is $7509.5 + $1736.7 = $9246.2 billion dollars.