Find the internal rate of return on a portfolio, which does reflect the timing of your cash flows.
The Modified Dietz approximation assumes cash flows arrive evenly through the period, so it weights them at half. It is close to a full internal rate of return for typical patterns and far easier to compute. Money-weighted return is what you actually earned, which is why it can differ sharply from the fund’s published time-weighted figure.
Money Weighted Return
Approximate MWR = gain ÷ (starting value + half of net cash flow)
Approximate MWR = gain ÷ (starting value + half of net cash flow) The Modified Dietz approximation assumes cash flows arrive evenly through the period, so it weights them at half. It is close to a full internal rate of return for typical patterns and far easier to compute.
Money-weighted return is what you actually earned, which is why it can differ sharply from the fund’s published time-weighted figure.
This calculator takes 5 inputs: Starting portfolio value, Contributions during the period, Withdrawals during the period, Ending portfolio value, Length of the period. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.