Money-Weighted Return Calculator
Estimate your personal rate of return using the Simple Dietz method — the return that accounts for the cash you added and withdrew.
How it works
Gain = end − begin − net contributions · MWR = gain ÷ (begin + ½ × net contributions) × 100
Money-weighted return is the return that reflects your actual cash-flow timing — it rises when you add money before a good run and falls when you add before a bad one. The Simple Dietz method used here is a clean approximation of the internal rate of return: it assumes all net contributions land in the middle of the period, so it divides the true gain by the average capital that was actually working. It is the fairest single number for how you did as an investor.
Worked example
You begin the year with $20,000, add $6,000 net during the year, and end at $29,000. The investment gain is 29,000 − 20,000 − 6,000 = $3,000. Average capital is 20,000 + 6,000 ÷ 2 = $23,000, so MWR = 3,000 ÷ 23,000 ≈ 13.0%.
Frequently asked questions
What is the Simple Dietz method?
It is a widely used shortcut for money-weighted return that assumes every deposit and withdrawal happens halfway through the period. That lets you compute a return with just three numbers instead of solving a full internal-rate-of-return equation.
How is this different from time-weighted return?
Money-weighted return is influenced by when you add or remove money, so it captures your personal experience. Time-weighted return removes that effect to judge the investments alone.
When is Simple Dietz inaccurate?
When large cash flows happen far from the mid-point, or when there are many flows spread unevenly. In those cases a full internal-rate-of-return calculation is more precise, though usually only by a fraction of a percent.
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Educational estimate, not investment advice. Past returns do not predict future results.