Trading Account Return Calculation With Deposits and Withdrawals

To calculate a trading account’s return when money has been added or removed, first separate external cash flows (deposits, withdrawals, transfers, payouts) from trading results (realized and open P&L, commissions, fees, financing). Then pick the measure that matches your question. Time-weighted return (TWR) measures how well trading compounded whatever capital was in the account; it splits the period at each external cash flow and chains the sub-period returns. Money-weighted return (MWR), usually an internal rate of return, measures what your money earned given when you added or removed it. If no money moved during the period, a simple return (net P&L divided by starting equity) answers both questions.

Ending balance divided by starting balance is not a return once a deposit or withdrawal has occurred. It counts your own deposit as if it were trading profit.

Neither TWR nor MWR is universally “correct.” The performance-measurement standards used by investment firms treat them as answers to different questions.¹² This page covers the calculation. Reviewing whether those results came from the intended risk and process belongs to the broader trading performance review.

Why a deposit or withdrawal breaks the simple calculation

A simple return assumes the capital base stayed fixed. Suppose an account starts at $20,000, you deposit $20,000 mid-quarter, and the account ends at $39,856. Ending over starting balance suggests roughly +99%. Net P&L after removing the deposit is −$144. Dividing that −$144 by the starting $20,000 still gives the wrong base, because for most of the quarter $40,000 or more was at risk.

The same problem happens in reverse with withdrawals, including a trader paying themselves from the account or taking a prop-firm payout. Any withdrawal shrinks the base for the rest of the period. If you ignore it, later gains or losses look larger than they were relative to the capital actually in the account.

Classify every cash movement before calculating anything

Every method depends on this step. The Global Investment Performance Standards (GIPS) define an external cash flow as capital that enters or exits a portfolio. They require returns after transaction costs, so trading costs belong in the result and are never treated as a flow.¹

Item	Usual classification	Why
Deposit from your bank	External cash flow (inflow)	New capital, not trading result
Withdrawal to your bank, including living-expense draws	External cash flow (outflow)	Capital leaving, not a trading loss
Transfer between two of your own accounts	External flow for each account	It is internal only if the accounts are measured together as one combined account
Prop-firm payout from a funded account	External outflow for the account balance	Removes balance; it is not a trading loss
Realized and open (marked) P&L	Performance	This is the result being measured
Commissions, exchange and regulatory fees, financing	Performance	They are the cost of producing the result
Interest credited on cash	Performance	GIPS includes returns on cash in the return calculation¹
Platform or data subscription charged to the account	Your policy; state it and apply it consistently	It can be treated as a trading cost or as a withdrawal for another purpose

Two rules prevent most errors:

Value the account at equity, not closed-trade balance. Include open positions at their marked value. Futures accounts settle open positions daily, so a statement’s cash balance and your journal’s trade-by-trade P&L can legitimately differ. The futures trading journal explains that reconciliation.
Record the value immediately before each flow. TWR needs the account value at the moment the capital base changes. A daily statement’s closing equity is a reasonable proxy if the flow posted after that close. Pick one timing convention and keep it.

Three calculations and the question each answers

Method	Question it answers	Data required	Use it when
Simple return: net P&L ÷ starting equity	How much did trading make or lose relative to the capital at the start?	Start and end equity, net P&L	No external flows occurred in the period
Time-weighted return (TWR)	How well did trading compound the capital that was in the account, regardless of when money moved?	Equity immediately before every external flow	Comparing periods, strategies, or accounts whose deposits and withdrawals differ
Money-weighted return (MWR / IRR)	What rate did the money I put in earn, given when I added and removed it?	Dated cash flows plus start and end equity	Judging the combined effect of trading and your own capital decisions

GIPS describes TWR as a method that negates the effects of external cash flows, and MWR as a return that reflects the timing and size of those flows.¹ The GIPS calculation guidance explains why firms normally present TWR: cash-flow timing is usually the client’s decision, not the manager’s. It also notes that money-weighted returns show the effect of that timing on the client.² A self-directed trader controls both the trades and the deposits, so both numbers are meaningful. They just describe different decisions.

Worked example: identical trading, opposite cash-flow timing

Two versions of the same 91-day quarter (July 1 to September 30). In both, trading gains 12% before a cash flow on day 30 and loses 6% after it. Only the direction of the cash flow differs.

	Account A: deposit	Account B: withdrawal
Starting equity (day 0)	$20,000	$40,000
Equity before flow (day 30, +12%)	$22,400	$44,800
External flow on day 30	+$20,000 deposit	−$24,800 withdrawal
Equity after flow	$42,400	$20,000
Ending equity (day 91, −6%)	$39,856	$18,800
Net trading P&L	−$144	+$3,600
Ending ÷ starting balance − 1 (wrong)	+99.3%	−53.0%
TWR	+5.28%	+5.28%
MWR (period IRR, not annualized)	−0.43%	+15.15%
Modified Dietz approximation	−0.43%	+15.40%

Arithmetic like this is illustrative only. It is not a performance target or a recommendation about when to add or withdraw capital.

Step by step: time-weighted return

Split the period at each external flow. Here that gives two sub-periods: day 0 to 30 and day 30 to 91.
For each sub-period, compute (ending value ÷ beginning value) − 1. The beginning value already includes any flow at the start of that sub-period. GIPS guidance gives this sub-period formula for a “true” time-weighted return.²
- Account A: 22,400 ÷ 20,000 − 1 = +12%. Then 39,856 ÷ 42,400 − 1 = −6%.
Chain the sub-period growth factors: (1.12 × 0.94) − 1 = +5.28%.

TWR is identical for both accounts because the trading was identical. The size and direction of the cash flows do not enter the result.

Step by step: money-weighted return

MWR finds the single rate that makes the starting equity and every dated flow grow to the ending equity. For Account A, that means solving 20,000 × (1 + r)^91 + 20,000 × (1 + r)^61 = 39,856 for a daily rate r, then compounding it over the 91 days. The result is about −0.43% for the quarter. Spreadsheet functions such as XIRR solve the same equation from dated cash flows and report an annualized figure.

Account A added capital just before the losing stretch, so more dollars experienced the −6% than the +12%. Account B withdrew before the losing stretch, so fewer dollars experienced the loss. Same trading, opposite capital timing, very different money-weighted results.

GIPS says returns for periods shorter than one year must not be annualized.¹ Annualizing Account B’s quarter would turn one favorably timed withdrawal into an implied yearly rate the account never earned.

When you lack a valuation on the flow date: Modified Dietz

If you only have month-end statements, you cannot compute exact sub-period returns. The Modified Dietz method approximates the result by weighting each flow by the fraction of the period it was in the account:

Return = (ending equity − starting equity − net flows) ÷ (starting equity + Σ flow × weight)

where weight = (days in period − day of flow) ÷ days in period. For Account A: −144 ÷ (20,000 + 20,000 × 61/91) ≈ −0.43%.

Modified Dietz is a cash-flow-weighted approximation. In this example it is very close to the period IRR, but the two methods are not identical, and the difference can widen when cash flows are large relative to equity or returns vary substantially within the period. GIPS calculation guidance lists it among the approximation methods firms may use for sub-periods, provided the sub-period results are geometrically linked across periods. Under GIPS, when daily returns are not calculated, portfolios must be valued at large cash flows and the resulting sub-period returns geometrically linked.²¹ Practically, keep flows few and period lengths short. If one flow is large relative to equity, record the equity on that date and compute a true sub-period return instead.

Funded and prop accounts: two different returns

A prop-firm funded account has two layers that should not be mixed. The first is the account balance’s trading return, calculated on the program’s stated balance, with payouts treated as external outflows. The second is your own money: fees you paid and payouts you received. The first describes trading on the notional balance. The second is a personal cash-flow question that the account statement alone cannot answer.

Whether the balance is simulated or live, and how payouts affect drawdown limits or balance thresholds, depends on the program’s terms. The evaluation-to-funded transition describes what changes between stages. Don’t calculate a percentage return on money you never deposited and then compare it with a personal account’s return as if the two were the same.

Checklist before you trust the number

Every flow has a date, an amount, a direction, and a classification. Anything unclassified gets resolved before calculating, not guessed.
Equity includes open positions at their marked value.
Fees and commissions are inside performance, not treated as withdrawals.
A transfer between your own accounts is a flow for each account, unless you are measuring the combined account.
The period, timing convention, and method are written next to the result, for example “Q3, TWR, flows at end of day, net of all trading costs.”
Returns for periods under a year are shown as period returns, not annualized.
Drawdown uses the same flow-adjusted base. Otherwise a withdrawal looks like a loss. Multi-day drawdown recovery asks you to state how deposits, withdrawals, and open P&L are handled for exactly this reason.

What the gap between TWR and MWR can show in review

An MWR below TWR is consistent with more capital being exposed during weaker stretches; an MWR above TWR is consistent with cash-flow timing that increased exposure during stronger stretches. With several deposits and withdrawals, the gap does not identify one specific cash-flow path. It is about capital decisions, not trade execution, and it cannot tell you whether the timing was skill, luck, necessity, or a repeatable behavior pattern.

It can raise a narrower review question. Were deposits made after a hot streak, and did position size rise with them? Were withdrawals forced by living expenses during a drawdown? For a trader who funds living costs from the account, part-time vs. full-time trading covers why scheduled withdrawals change the pressure on a drawdown. Treat any pattern as a question for the next review, not proof from one quarter.

Where Costante fits

Costante does not connect to brokers or exchanges and does not import statements or calculate TWR, MWR, or account returns. It supports the behavioral layer around a trader’s own method: session planning, self-defined guardrails, pre-trade and in-session checks, low-friction logging, and structured review. If adding capital, raising size after a deposit, or withdrawing during a drawdown is a decision you want to plan and review deliberately, that is the kind of process Costante is built to make observable. The trader remains responsible for the calculation, the capital decisions, and every order.

Common questions

Should I use TWR or MWR for my trading account?

Use TWR to evaluate trading performance across periods or accounts while removing the effect of external cash-flow timing. Use MWR to see what your own capital actually earned, given the timing and size of your deposits and withdrawals. Many traders keep both and label which is which.

Do commissions and fees count as withdrawals?

No. Commissions, exchange fees, and financing are costs of trading and belong in performance. GIPS requires returns to be calculated after transaction costs.¹ Only capital entering or leaving the account is an external cash flow.

Why does my broker’s return differ from my own calculation?

Usually the method, period, or cash-flow timing differs. A broker report may use either measure, so check its methodology note. Interactive Brokers’ glossary, for example, describes TWR as linking sub-period returns so cash-flow timing drops out, and MWR as influenced by the timing of contributions and withdrawals.³⁴ Match the method, the period boundaries, and the flow classification before treating a gap as an error.

Sources

Costante provides educational workflow tools, not financial advice. Trading involves risk.

CFA Institute. Global Investment Performance Standards (GIPS) for Firms, 2020. Glossary definitions of external cash flow (“capital (cash or investments) that enters or exits a portfolio”), time-weighted return, money-weighted return, and large cash flow. Section 2.A requirements covering returns after transaction costs, inclusion of returns from cash, valuation at large cash flows with geometric linking of sub-period returns, money-weighted returns using daily external cash flows, and no annualization for periods under one year. Written for investment firms, not individual traders. Accessed September 23, 2026. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷
CFA Institute. GIPS Guidance Statement on Calculation Methodology. Gives the “true” time-weighted sub-period formula and geometric linking, lists approximation methods including Modified Dietz and Modified IRR, and explains why time-weighted returns are used for comparison while money-weighted returns show the effect of cash-flow timing. Accessed September 23, 2026. ↩ ↩² ↩³ ↩⁴
Interactive Brokers. Time-Weighted Return. IBKR Campus glossary. Accessed September 23, 2026. ↩
Interactive Brokers. Money Weighted Return (MWR). IBKR Campus glossary. Accessed September 23, 2026. ↩