Account growth can come from funding rather than returns
An investment account can end with more money because new cash was deposited, because holdings earned a gain, or both. It can also grow despite an investment loss if the new deposits are large enough. The percentage increase in statement balance is therefore not automatically an investment return. First reconcile how money entered and left the account during the measurement period.
This distinction matters when comparing a contribution plan with a performance report. The Investment Calculator projects a funding schedule and hypothetical growth scenarios; it does not infer actual returns from two statement balances. This guide explains a cash-reconciliation framework, not a recommendation for an asset or an audit of a particular brokerage's reporting method.
Use an explicit account-boundary identity
Let B_start be opening value, B_end ending value, D external deposits and W external withdrawals over the same period. A simple reconciliation is net investment gain = B_end − B_start − D + W. Define the boundary and included charges consistently. The identity measures a dollar residual; it does not by itself produce a performance percentage that correctly weights every cash-flow date.
For example, moving money between two investments inside the same measured account is not a new external contribution to that whole account. Measuring just one subaccount can give that transfer a different classification. Keep the chosen boundary with the record so that a transaction is not counted once as internal reallocation and again as new money.
A higher balance can coexist with a loss
Suppose a hypothetical account starts at $10,000, receives $5,000 of external deposits, has no withdrawals and ends at $14,000. The statement balance rose by $4,000, or 40 percent of the opening value. Yet the cash reconciliation is $14,000 − $10,000 − $5,000 = −$1,000. Under the stated boundary, the account has a net investment loss despite its higher balance.
Dividing that loss by the $15,000 total supplied gives about −6.67 percent as an aggregate loss-to-funding ratio. That ratio should not automatically be labeled the account's annual performance. A deposit made at the start and one made near the end did not have equal time exposed to returns. The missing dates are economically meaningful, not cosmetic details.
A lower balance need not mean the same amount was lost
For a second illustration, start at $10,000, withdraw $3,000, make no new deposits and end at $8,000. The balance fell by $2,000, but the reconciliation gives $8,000 − $10,000 + $3,000 = $1,000 net gain. The withdrawal is money deliberately removed, not necessarily a market loss. Record it before interpreting the change between statements.
This does not establish a unique percentage return either. The value of holdings when the withdrawal occurred and the timing of gains can matter to performance measurement. A contribution or withdrawal log supplies information that opening and ending balances alone do not contain. Do not use the identity as a substitute for dated calculations when the question specifically concerns investment performance.
Distinguish internal distributions from outside deposits
A dividend paid into the account is income generated by an investment, not new money contributed by the investor from outside. Reinvesting that dividend changes cash into additional holdings inside the boundary. Counting it as an external deposit would remove investment income from the gain residual and misstate the source of the account's growth.
If the dividend is transferred out, its treatment must match the chosen boundary: investment income and the external withdrawal need a consistent record. The separate dividend-reinvestment guide tracks shares and retained cash explicitly. Fees deducted inside the account can reduce the residual; keep gross income and charges separate if the goal is to distinguish gross performance from net gain.
A dollar gain is not enough to choose one percentage measure
Money-weighted measures such as an appropriately calculated IRR or XIRR incorporate the timing and size of investor cash flows. A time-weighted measure instead links subperiod performance after accounting for external cash movements. These answer different questions and can disagree without either being a simple arithmetic error. A report should state its method rather than use the word return without definition.
The ROI Calculator also has a narrower transaction model: initial cost, ending value, income and selected fees. It does not accept an arbitrary series of deposits with dates. Do not enter a year's total deposits as though all were invested at inception and then claim that its annualized output measures the actual account performance. Use an appropriate dated-flow or valuation method separately.
Read the Investment Calculator's funding and gain outputs separately
For a zero-return, zero-fee illustration, enter $1,000 initially, $100 monthly for twelve months and zero for all three return scenarios. Total contributed and projected ending balance are both $2,200, and gain is zero. The account more than doubles relative to opening value because contributions supplied $1,200. That increase is not evidence of a 120 percent investment return.
When return assumptions are nonzero, each scenario still separates contributed money and modeled gain. The displayed annual assumptions generate a smooth projection; they do not estimate the historical money-weighted return of your account. Changing the monthly contribution can increase the ending balance even when the scenario return stays the same. Compare both columns before calling one funding plan better-performing.
Keep a reproducible funding and performance record
Record the start and end dates, opening and ending values, external transfers, cash income, charges and the account boundary. If performance rates are needed, preserve transaction dates and the relevant valuation information instead of discarding them after summing deposits. Confirm whether fees are already reflected in the reported balance to avoid deducting them twice in a separate calculation.
This guide is educational, not investment, accounting or tax advice. It does not calculate a tax cost basis or certify a provider's return report. Its central check is simple: explain the balance change before interpreting it as profit. A good reconciliation separates funding, withdrawals and net gain, and a good performance percentage then uses a method appropriate to the timing of those flows.