Position Size Calculator

How to use

1. 1Enter your account size in the currency you trade in, then pick the matching currency for display.
2. 2Choose how to size: a percent of the account (typical: 0.5% to 2%) or a flat dollar risk amount.
3. 3Pick a direction, then enter the entry price and the stop-loss price on the protected side of the entry.
4. 4Optionally enter a take-profit price to compute the R-multiple and projected gain at the target.
5. 5Pick whether your broker allows whole units, fractional units, or a custom increment, and set a position cap if you want oversized trades flagged.
6. 6Read the recommended position size, actual dollar risk, position percent of account, and the warnings, then copy the trade plan summary.

About this tool

Position Size Calculator answers the single most important question a trader can ask before clicking buy or sell: how many shares, contracts, or units should this trade be? Type your account size, choose whether you size by a percent of the account or by a flat dollar risk, enter the entry price and the stop-loss, and the tool computes the exact position size that caps your loss at the planned risk if the stop is hit. It supports both long and short trades and validates that the stop is on the protected side of the entry (below for longs, above for shorts) so a typo cannot silently triple your real risk. The size is floored to whatever increment your broker supports: whole units for stocks and ETFs, four decimals for fractional shares and most crypto exchanges, or a custom step for futures lots and exotic instruments, so the displayed size is always a number you can actually submit. An optional take-profit price unlocks the second half of the trade plan: reward per unit at the rounded size, projected percent gain on the account if the target prints, and the R-multiple (reward divided by planned risk) that risk managers and trading journals expect. A configurable position cap warns when a single trade would use more than your chosen share of the account (10% to 30% are typical limits), and the tool flags unusually tight stops, take-profits on the wrong side of the entry, and reward-to-risk ratios below 1R. The Copy trade plan button hands you a clean text summary ready to drop into a trading journal, a Discord trade idea, a brokerage note, or a spreadsheet row. Useful for swing traders sizing positions on stocks, ETFs, and indices; day traders running fixed risk per setup; futures traders converting tick risk into lots; crypto traders working in fractional units; options traders sizing the underlying for delta-equivalent exposure; and anyone keeping a trading journal that tracks R-multiples. The calculator runs entirely in your browser. No quotes are fetched, no brokerage credentials are required, and the values you type never leave your device.

Free to use. Works in your browser. No signup, no login.