Money management tool
Lot Calculator
Work out the optimal lot size and the maximum loss from your account balance, risk percentage and stop-loss distance.
- No registration
- Free
- Calculated in your browser
For money management before trading or running an EA
Result
Optimal lot
0.00Lot
Max Loss Amount
-JPY
Estimated margin required
-JPY
Risk against your balance
-%
Assessment:
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Risk guide
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How to read this result
What the optimal lot means
The lot size that keeps the risk on a single trade constant, based on the risk percentage and stop-loss distance you set.
What the maximum loss means
The loss you should expect if price reaches your stop.
Points to watch
Keeping the risk on one trade within 1-2% of your account balance is the common recommendation.
Method and specification
Main inputs used
Account balance / Risk % / Stop loss / Currency pair
When to use it
Checking the lot before entry / Money management before running an EA
Notes
The margin your broker actually requires may differ. The reference rate is used exactly as entered.
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Frequently Asked Questions
What is a lot calculator for?
It keeps the amount you can lose on a single trade inside a range you decided in advance. If you size lots by feel, the days with a wide stop become the days with an outsized loss, and your capital drains unevenly. Working the lot size back from your account balance, risk percentage and stop-loss distance keeps the loss per trade roughly constant in any market.
How much of my account should I risk on a single trade?
Keeping it within 1-2% of your account per trade is the common recommendation. At 2%, ten losses in a row still leave about 80% of your capital, so recovery stays realistic. This tool flags anything above 5% as caution and above 10% as a warning.
Do I still need lot sizing when I run an EA?
Yes. An EA's default lot size is usually based on the balance used in its backtest, so leaving it unchanged shifts your actual risk percentage. Check the appropriate lot here before you start it, and put that value into the EA's parameters.
Once your money management is settled, the next step is choosing an EA.
Browse free EAs and the rankings to compare the approach that suits you.