Question: is 1gb of data more than 500mb?
Answer: You can read about these in more detail here. For a 500MB data allowance, you should half all of the figures above (as a 500MB allowance is equal to 0.5GB). For a data allowance that's larger than 1GB, simply multiply up the figures as appropriate (e.g. multiply by 4 if you have a 4GB download allowance).