Position Sizing With the 1% Rule: The Real Math on a $25K Account

Ask a room of traders what their edge is and you will get a dozen answers about setups, indicators, and entries. Ask them what they risk per trade and the room gets quiet.

That is backwards. Position sizing is the one variable you control completely. You cannot control whether a trade works. You can control exactly how much it costs you when it does not.

The 1% rule is the most common answer to that question, and it is also the most commonly misunderstood. Let us run the actual math on a $25,000 account.

What the 1% rule actually says

The rule is not "put 1% of your account into a trade." That is a position size, and it is a different thing entirely.

The rule is: risk no more than 1% of your account on any single trade. Risk means what you lose if the trade goes against you and you exit at your stop.

On a $25,000 account, 1% is $250. That is your maximum loss on one idea. Not your position size — your loss.

From there, the sizing formula is straightforward:

Shares = Risk Dollars ÷ (Entry − Stop)

Running it on a stock trade

Say you like a setup at $50 and your chart says the idea is wrong below $47.50. Your stop distance is $2.50 per share.

$250 ÷ $2.50 = 100 shares.

That is a $5,000 position — 20% of the account — risking $250. Notice that the position size and the risk are completely different numbers. This is the part people miss.

Now take the same account and a different setup. You like a stock at $50 but the structure that invalidates the trade is way down at $42.50. Stop distance is $7.50.

$250 ÷ $7.50 = 33 shares. A $1,650 position.

Same account. Same $250 of risk. A position one-third the size, because the trade required more room. That is the entire point of sizing off risk instead of off dollars: the chart determines the stop, and the stop determines the size. Not the other way around.

The trap is doing it backwards — picking a position size you like, then placing the stop wherever it needs to be to make the position "feel" reasonable. That is how a $250 plan becomes a $900 loss.

Running it on options

Options change the arithmetic but not the principle.

Long options. If you are buying a call or a put and you would let it go to zero rather than manage it, the entire premium is your risk. On a $25,000 account, that caps a full-risk long option position at $250. One contract at $2.50. If you plan to cut it at a 50% loss instead, $500 of premium puts $250 at risk — but only if you actually honor that exit, including on a gap.

Defined-risk spreads. This is where sizing gets clean. A $5-wide vertical sold for $1.50 has $3.50 of risk per contract, or $350. On a $25,000 account, that is already above the $250 line — so the honest answer is that you either trade a narrower spread or you accept that this position is oversized.

That is not a limitation. That is the math telling you something true about the trade.

Cash-secured puts. The risk here is not the margin requirement, it is what happens if the stock drops. Selling a $50 put means you are on the hook for $5,000 of stock. Sizing that as if the risk were the $200 premium is how small accounts get concentrated without realizing it.

The number that matters more than any single trade

Here is why the 1% rule exists, and it is not about any one position.

Losses do not cost what they appear to cost, because gains have to work against a smaller base to recover. The recovery math is brutal at the extremes:

• Down 10% → you need 11% to get back to even
• Down 25% → you need 33%
• Down 50% → you need 100%
• Down 75% → you need 300%

At 1% risk per trade, ten consecutive losers — a stretch every trader eventually gets — puts you down roughly 10%. Unpleasant, and completely survivable. You are still trading with a working process and a clear head.

At 5% risk per trade, that same losing streak takes you down about 40%. Now you need a 67% gain just to get back to where you started, and you are almost certainly not making calm decisions while you try.

The streak is not the difference. The sizing is.

Three rules that do the real work

Count correlated positions as one. Four semiconductor trades at 1% each is not four positions risking 1%. It is one macro bet risking 4%. Sector and correlation exposure is where "disciplined" sizing quietly turns into concentration.

Cap your total open risk. Pick a number — many traders use 5% or 6% of the account across all open positions — and stop adding when you hit it. Position sizing without a portfolio cap only solves half the problem.

Size off the account you have. Recalculate your 1% periodically, not per trade. Growing accounts should let size grow. Drawdowns should shrink it. A trader who keeps risking $250 after the account has fallen to $18,000 is quietly risking 1.4% and rising.

When 1% is the wrong number

The 1% rule is a starting point, not a commandment.

A smaller account may find that 1% makes some trades impossible to size at all — a stock that needs a wide stop simply cannot be traded with $250 of risk in single shares. That is useful information: it points you toward instruments that fit your account, not toward stretching the risk.

A trader with a long, documented record and a stable process may run more. A trader in a drawdown, trading a new strategy, or coming back after time away should run less — half a percent while the process gets proven again is a perfectly professional decision.

What does not vary is the discipline underneath it: know the number before you enter, size to it, and let the stop live where the chart says it belongs.

Do the boring part well

Nobody joins a trading community to learn arithmetic. But position sizing is the difference between a bad month and a blown account, and it is the single fastest thing a trader can fix.

Pick your number. Calculate it before every entry. Write it in your journal next to the result. After 50 trades, you will know more about your own edge than any indicator will ever tell you.

If you want to work through this with coaches who have spent decades doing it — including risk frameworks, defined-risk spreads, and the swing trading process end to end — you can start a 15-day free trial with AJ Monte here. No credit card required.

Sticky Trades provides trading education, not financial advice. Nothing above is a recommendation to buy or sell any security. Trading involves risk of loss.