Margin Call Calculator
The margin call price is the price at which your equity falls below the broker's maintenance requirement. It is the loan divided by your share count times one minus that requirement, and it is the real stop on the position whatever your intended stop says.
Where the call comes
Work it out before the order exists. After it exists the arithmetic has no influence.
The call price is loan ÷ (shares × (1 − maintenance)). Notice the entry price is not in it — only the loan, the share count and the requirement.
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How the number is built
A margin position has two parts: your money and the broker’s. As the price falls, the loss comes out of your part first. The call arrives when what remains is too thin a share of the position.
The condition is a ratio. Your equity divided by the position’s value must stay above the maintenance requirement:
(shares × price − loan) ÷ (shares × price) ≥ maintenance
Rearranged for the price, it becomes:
Call price = loan ÷ (shares × (1 − maintenance))
The entry price has vanished from that formula. What matters is how much you borrowed, how many shares that bought, and the requirement — not what you paid. That is the first thing most people get wrong about it.
A worked example
Take the defaults: 100 shares at 50, funded with 2,500 of your own money and a 25% maintenance requirement.
The position is worth 5,000 and you put in 2,500, so the loan is 2,500. That is 2x leverage, which the calculator reports so it is visible rather than implied.
The call price is 2,500 ÷ (100 × 0.75) = 33.33.
Which means the price can fall 33.3% before the call. That sounds comfortable until you notice what it is measured against.
On this site’s shared series a typical bar spans 0.493 and the widest measured 2.338. A 33% fall is many bars away on that series — but raise the leverage to 4x by depositing 1,250 instead, and the call price rises to 50.00, which is the entry itself. The position would be callable immediately.
Buying power versus the requirement
Brokers display buying power, which is what they will lend. It is presented as capacity and reads as a recommendation. Nothing about it says how far the price can move before the position is taken away from you.
The maintenance requirement is the number with consequences, and working backwards from it is what turns leverage from a feeling into a size. Pick the deposit so the call price sits outside any move you would accept, then check that distance in typical bars.
And a call is not a notification. It is a demand with a time limit attached.
Choosing the deposit backwards
The useful version of this formula is the one solved for the deposit. You decide how far you are willing to let the price fall before a call, and it tells you how much of your own money the position needs:
Deposit = shares × entry × (1 − (1 − fall) × (1 − maintenance))
At 100 shares of 50 with a 25% requirement, a 30% fall needs 2,375 of your own money — a loan of 2,625, a call price of 35.00 and 2.11x leverage.
Wanting a 50% cushion instead needs 3,125, which drops the leverage to 1.60x and puts the call at 25.00. Wanting 70% needs 3,875 and 1.29x.
Read those three together and the trade-off is explicit. Every extra unit of cushion is bought with leverage you give up, and the relationship is not linear — the last twenty percentage points of safety cost less leverage than the first thirty did.
What happens if you miss it
The broker liquidates, and they choose what goes. Not the position you would have picked, and not at a time you would have chosen — typically whatever is easiest to sell.
In a thin market the forced sale moves the price against the seller, which is you. Leverage on an illiquid instrument compounds exactly the problem it created.
And the liquidation is a transaction like any other. A round trip on the shared series is 2% of a median bar’s range, paid on a trade you did not choose to make.
The original data
Of the 24,971 unique videos in research/search-study-corpus.jsonl, zero have an
instruction-shaped title about calculating a margin call price. Leverage appears in 17
instruction-shaped titles at a median of 16,703 views, and margin in 9 at 38,013. The counts come
from site/rank_tools2.py, which deduplicates by video id.
Nine videos on margin at a 38,013 median, and none on the arithmetic that decides when it ends you. That is the pattern across every zero-coverage subject on this site: the concept is discussed and the number is not, because the number requires a formula and the concept only requires an opinion.
The answer to the question on that chart is that meeting a call is a new purchase. Ask whether you would open this position, at this price, at this size, with fresh money. If the answer is no, adding funds is buying something you would not buy — funded by the fact that you already own it.
When it fails
A gap through the call price is the failure nothing prevents. Price opens beyond the level, there was no trading in between, and the position is already liquidatable before you have looked at a screen. A stop cannot help — a stop is a request that becomes a market order, and it cannot fill at a price that never existed. Sizing is the only defence, which is why the calculator reports leverage alongside the call price.
The second failure is a requirement that changes. Brokers raise maintenance requirements on volatile instruments, sometimes with little notice, and a higher requirement moves the call price up toward the current price.
A third is treating buying power as the plan. It is the ceiling on what they will lend, and using all of it puts the call price close enough that ordinary movement reaches it.
A fourth is ignoring the interest. The loan accrues daily, which slowly reduces your equity and therefore slowly raises the call price even in a flat market.
A fifth is holding several leveraged positions. They share one equity balance, so a fall in one can trigger a call that liquidates another.
And a sixth is meeting a call by adding funds without re-examining the position. That converts a sizing error into a larger sizing error at a worse price.
Related
Margin account covers what the account is and how the two requirements differ. Leverage trading is the mechanism and what it does to a drawdown. And drawdown is the measurement the call price is really about.
The habit that keeps me out of trouble is drawing the call price on the chart as a line before the order goes in. It stops being an abstract broker rule and becomes a level, sitting there next to the other levels — and it is almost always closer than it feels when you are looking at buying power instead.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money.