Capital gain calculation on mutual fund
Does anyone have any idea how to calculate capital gain/loss on mutual fund using the average cost single category? To be specific, I'm considering to cash out one of the fund that I have invested "monthly" for 7+ years. Technically, the monthly investment and the dividend reinvestment that were made within the past 12 months are considered short term investment with a 28% tax rate while investment made over 12 months ago should be considered long term with 15% tax rate. How do I calculate it using the average cost single category method?