For fixed ratio method, suggest make delta 50% or less as of the expected maximum drawdown. Since for your system the actual dd in the last 10 years in $2,780 , so if I were you, I would give it some breath space and make 1.5*$2,780=$4,170 as the expected MDD, then the delta is 0.5*4170=$2,085. In fixed ratio method, it means when you make $2,085 for EVERY contract traded with this strategy , you increase trade size by one additional contract. Thus if you start with $7,500 to trade one contract , you increase to trading two contract if the profit has reached $7500+1*$2085=$9585, and you increase to trading three contracts when the accumulated profit has reached $7500+1*2085+2*2085=$13,755, ...... If you have dd and the accumulated profit drop below the thresholds, you just scale down the size to the previous ones. This is how fixed ratio works, it is agressive for starting and smaller accounts, since it increase the trade size rapidly at first. Of course it involves bigger risk , and you should not adopt this method randomly with any strategy. But then the strategy you are testing is (IMO) very good, and it seems to be an intraday system, ( or is it ?) , which means limited risk, so I do not see why you cannot use it with fixed ratio method. And let's say your account size increases smoothly with fixed ratio . At first the risk of trades (calculated with expected MDD ) as a percentage of the whole trade account ( $7500 plus profits) increases as you increase the trade size . Let's say at first this risk percentage is smaller than the risk percentage of the fixed fractional method, which is a constant in its turn. At some point ( Point A ) the risk percentage of fixed ratio will cross up ( begin to be bigger than) the risk percentage of fixed ratio method. However, this increasing tendency will not last forever, the risk percentage of fixed ratio will reach its climax and begin to goes down (Point B ), at some later point(Point C ), it will cross down ( begin to be less than ) the risk percentage of fixed fractional methold. For me I would like to make point C the point when I switch from fixed ratio to fixed fractional method. ( from point C, fixed ratio begins to be too conservative compared with fixed fractional, of course the conclusion comes differently with each one's preference with risk ) I used to have a chart made with Excel , with x-axis indicating number of contracts traded and y-axis indicating trade risk as a percentage of the account size, but somehow I cannot find it now. You may make one and I think that is the best way to learn about various position sizing methods. To know more about fixed ratio method, I suggest you read book " The trading game " by Ryan Jones, he is the first to come up with the idea of fixed ratio. Of course more books/articles as mentioned by other posters in the thread are also helpful to get a broader knowledge of position sizing possibility. Actually for position sizing, the choice is multiple. You may also want to include volatility into your algorithm, that will make you comfortable even in dramatical trading climates.