Portfolio Return Calculator

How to Use

Enter your portfolio's beginning and ending value for the period, plus any net contributions (money you added minus money you withdrew during that time). The calculator separates your actual investment gain from cash you moved in or out, then shows return as a percentage of your beginning value, updating live as you type. Leave Net Contributions at 0 if the period had no deposits or withdrawals, in which case investment gain and raw value change will be identical.

Why Raw Value Change Alone Is a Misleading Return Metric

A portfolio's ending value minus its beginning value tells you how much bigger or smaller the account got, but it doesn't tell you why. That raw change is a mix of two entirely different things, actual investment performance (prices going up or down) and your own deliberate cash movements (deposits and withdrawals), and conflating the two produces a return figure that overstates performance for anyone who added money during the period, and understates it for anyone who withdrew money. This calculator's whole purpose is separating those two effects, so the reported percentage reflects how your investments actually performed, not how much extra cash you happened to deposit.

Worked Example: Isolating Gain From a Mid-Period Deposit

Using this tool's own defaults, a beginning portfolio value of 500,000, an ending value of 620,000, and net contributions of 50,000 (money added during the period). Raw value change is straightforward, 620,000 − 500,000 = 120,000. But not all of that increase came from investment performance, 50,000 of it was simply new money deposited. Subtracting that out gives the actual investment gain: 120,000 − 50,000 = 70,000. Dividing that gain by the beginning value gives the return percentage: 70,000 ÷ 500,000 = 14%. Without the contribution adjustment, a naive calculation would have reported 120,000 ÷ 500,000 = 24% return, nearly double the true 14% investment performance, purely because it mistook a deposit for investment growth.

Why Brokers May Show a Different Number

This calculator applies a single net-contribution adjustment across the whole period, which is a reasonable approximation but not identical to what a brokerage or portfolio-tracking platform typically calculates. Professional-grade return calculations use time-weighted return, which breaks the period into sub-periods around each cash flow and compounds the returns of each sub-period together, correctly isolating performance regardless of when contributions happened. A single large contribution made right before a strong market rally, versus the same contribution made right before a downturn, would produce different time-weighted results even with identical beginning value, ending value, and total contribution amount, a distinction this simpler calculator can't capture since it doesn't ask when contributions occurred, only how much.

When This Simplified Method Is Accurate Enough

For a period with no contributions or withdrawals at all, this calculator's result is exact, not an approximation, since there's no timing effect to account for when net contributions are zero. It's also a reasonably close approximation whenever contributions are small relative to the portfolio's total size, or when they happen consistently rather than as one large lump sum at an unusual moment. The approximation gets progressively less accurate the larger a single contribution is relative to the portfolio, and the more that contribution's timing happens to coincide with an unusually strong or weak stretch of market performance within the period.

Using This Tool to Compare Performance Across Periods or Accounts

Because this calculator produces a clean percentage return isolated from contribution effects, it's well suited to comparing performance across different time periods for the same portfolio, or across different accounts entirely, even ones that received very different amounts of new money. Running the same beginning-value, ending-value, contribution calculation quarter over quarter builds a comparable series of return figures over time, useful for spotting whether performance is trending up or down independent of how much you happened to add or withdraw in any given quarter.

Frequently Asked Questions

Why does this calculator ask for contributions or withdrawals?

If you added or withdrew money during the period, comparing raw beginning and ending values would mix your actual investment gain with your own cash movements. Subtracting net contributions isolates the portfolio's real performance, not just the fact that you deposited more money.

Is this the same as the return my broker shows?

It's a simplified approximation. Brokers typically use time-weighted or money-weighted return methods that account for exactly when each contribution happened during the period, which can differ from this calculator's single net-contribution adjustment, especially with large mid-period cash flows.

What's the difference between time-weighted and money-weighted return?

Time-weighted return measures the portfolio's actual investment performance, isolated from the effect of when money was added or withdrawn, it's the standard method for judging a manager's or strategy's skill. Money-weighted return (also called dollar-weighted return) factors in the size and timing of your own contributions, so it reflects your personal actual return given your specific deposit and withdrawal pattern, which can differ meaningfully from time-weighted return if you added or removed large amounts at particularly good or bad moments.

Why does a large contribution mid-period distort a simple return calculation?

A raw ending-minus-beginning-value calculation can't distinguish between money that grew through investment performance and money that simply arrived as a new deposit, both increase the ending value identically. This calculator's net contribution adjustment corrects for the total amount added or withdrawn, but it applies that correction as if it happened all at once rather than at its actual point in time, which is exactly why very large contributions made partway through the period can still skew the result compared to a full time-weighted calculation.

Can portfolio return be negative even if the ending value is higher than the beginning value?

Yes, if net contributions exceed the actual investment gain. For example, a portfolio that grows in raw value but only because a large new deposit was added, with the underlying investments actually losing value, can show a negative return once that contribution is subtracted out, even though the ending value on paper looks higher than the beginning value.

Should withdrawals be entered as negative numbers in the Net Contributions field?

Yes, Net Contributions should represent money added minus money withdrawn during the period. If you withdrew more than you contributed, enter that as a negative number, the calculator adds this figure back when isolating investment gain, so a negative net contribution correctly increases the calculated gain relative to the raw value change, matching money that left the portfolio for reasons unrelated to investment performance.