Typical Price = ( (Day High + Day Low + Day Close) / 3)
Raw Money Flow = (Typical Price) x (Volume)
Positive Money Flow = Sum of Raw Money Flow for the specified number of periods where Typical Price increased
Negative Money Flow = Sum of Raw Money Flow for the specified number of periods where Typical Price decreased
Money Ratio = (Positive Money Flow / Negative Money Flow)
Finally, the MFI can be calculated directly from the Money Ratio: