Margin Interest & Break-Even Calculator
Enter the stock price, shares, debit balance, margin rate, and holding period to estimate interest cost, net profit, and the sale price needed to break even.
Break-even sale price$50.25
- Total position cost
- $5,000.00
- Investor cash used
- $2,500.00
- Estimated margin interest
- $25.00
- Net profit or loss
- $475.00
- Return on investor cash
- 19%
- Price gain needed to break even
- 0.5%
- Estimated margin-call price after holding period
- $36.07
Trade breakdown
| Item | Amount |
|---|---|
| Sale proceeds | $5,500.00 |
| Dividends received | $0.00 |
| Purchase cost | -$5,000.00 |
| Margin interest | -$25.00 |
| Trading fees | -$0.00 |
| Net profit or loss | $475.00 |
Interest uses a 360-day year and assumes the debit balance stays constant.
How to use this calculator
- Enter the purchase price and number of shares in the position.
- Enter the margin debit, annual margin rate, holding days, and the day-count basis your broker uses.
- Add the expected sale price, dividends, trading fees, and maintenance margin requirement.
- Read the break-even sale price, estimated interest, net result, and margin-call price.
How the margin trade is calculated
This calculator treats a margin purchase as one stock position funded partly with investor cash and partly with a margin debit. It estimates simple margin interest over the holding period, then subtracts that borrowing cost from the trade result.
The main formulas are:
position cost = purchase price × shares
investor cash = position cost − amount borrowed
margin interest = amount borrowed × annual rate × days held ÷ day-count basis
net profit or loss = sale proceeds + dividends − position cost − margin interest − trading fees
break-even sale price = (position cost + margin interest + trading fees − dividends) ÷ shares
margin-call price = (amount borrowed + interest) ÷ (shares × (1 − maintenance margin))
The return on investor cash divides the net profit or loss by the cash portion of the trade. If the borrowing equals the full position cost, that return is undefined because there is no positive cash base to divide by.
What moves the break-even price
The borrowed amount, margin rate, and holding period drive the interest charge. A higher debit balance or a longer holding period raises the break-even sale price because the stock has to cover more borrowing cost before the trade is profitable. Dividends move the other way: dividends received during the holding period reduce the sale price needed to break even.
Trading fees are entered as one total because they reduce the trade result whether they are paid at purchase, sale, or both. For a fully amortizing loan, use the loan payment calculator instead; margin interest is usually charged against a variable debit balance, not repaid on a fixed installment schedule.
What the margin-call estimate means
The margin-call price is a simplified equity test. It assumes this is the only margined position, the margin debit grows by the estimated interest, and the broker applies the maintenance requirement you entered. If the estimate is at or above the purchase price, the position starts with little room before a call.
What this calculator leaves out
Real brokerage statements may use average daily balances, tiered rates, statement-cycle posting, different day-count conventions, or security-specific margin rules. This tool also leaves out taxes, bid-ask spreads, slippage, short-sale fees, forced liquidation risk, and any change in house requirements.
Worked example
Suppose you buy 100 shares at $50, borrow $2,500, and hold the position for 30 days at a 12% annual margin rate using a 360-day basis. The position cost is $5,000 and the investor cash used is $2,500. Interest is $2,500 × 12% × 30 ÷ 360, or $25.
If the expected sale price is $55 and there are no dividends or trading fees, sale proceeds are $5,500 and net profit is $475. The return on investor cash is 19%. The break-even sale price is ($5,000 + $25) ÷ 100, or $50.25, and the estimated margin-call price at a 30% maintenance requirement is $36.07.
Common questions
How is margin interest calculated each day?
Brokers generally apply an annual margin rate to the debit balance and prorate it by the number of days the debit is outstanding. This calculator uses simple interest: amount borrowed times annual rate times days held, divided by either 360 or 365.
Do brokers use 360 or 365 days for margin interest?
Brokerage firms can use different day-count conventions, and the convention may be described in the margin rate or account agreement materials. Use the basis your broker uses when you want the estimate to line up with a statement.
When does margin interest begin and stop accruing?
Margin interest usually accrues while a debit balance is outstanding in the margin account. It can begin when the debit is created and stop when the debit is repaid, but posting and settlement details can vary by broker.
How do dividends affect profit on a margin trade?
Dividends received during the holding period add to the trade result. In this calculator they reduce the break-even sale price because the stock does not need to provide as much price gain to cover interest and fees.
What price could trigger a margin call?
The estimated margin-call price divides the debit plus accrued interest by the shares times one minus the maintenance margin. It is a simplified single-position estimate, so it can differ from a broker's actual house calculation.
Is margin interest tax deductible?
Margin interest may be investment interest expense for some taxpayers, but limits and elections can apply. This calculator does not provide tax advice; ask a qualified tax professional how the rules apply to your account.