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Stock position size calculator

How many shares can you buy so your stop loses only what you planned? Type entry, stop and risk.

The formula

Shares = Risk $ ÷ (Entry − Stop), rounded to whole shares inside your range. A $50 entry with a $48 stop risks $2 per share; $250 ÷ $2 = 125 shares.

Remember that the stop can slip in fast markets and gaps, so the real loss can be bigger than planned.

Questions

How many shares should I buy?

Shares = dollars you are willing to lose ÷ (entry price − stop price). Example: $250 risk, entry $50, stop $48: $2 risk per share, so 125 shares.

Does position size depend on account size?

Only through the dollar risk you choose. Many traders risk a small fixed share of their account per trade, for example 0.5% to 1%. Type that dollar amount as your target.

Does this work for short trades?

Yes. Put the stop above the entry and the calculator treats it as a short.

Get the SizeGuard app

Same math, in your pocket: SizeGuard remembers your risk, picks standard or micro for you, adds fees and daily loss limits, and logs every trade in a journal. Works offline, no account.

Free 7-day trial, then a one-time $9.99 unlock. No subscription.

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