Lot Size Limits and Maximum Exposure Rules at Prop Firms

[FXS Prop Desk]

Besides drawdown, many firms cap how much you can hold at once. Common forms:

• Maximum lots per trade (e.g. 20 lots on a 100k account).
• Maximum total open lots across all positions.
• Maximum lots per instrument, often lower on indices or gold.
• Leverage caps per asset class (e.g. 1:100 FX, 1:20 indices, 1:2 crypto).

Why it matters for scalpers: stacking several entries on the same move ("scaling in") can exceed the total open-lot limit faster than expected, and the platform may simply reject the next order at the worst moment.

Useful habit: write down the effective max position for each instrument you trade, already converted into your normal risk. If 1% risk with a 3-pip stop on EURUSD would require more lots than allowed, your stop is too tight for that account size.

Have you ever had an order rejected because of a lot or exposure limit, and on which instrument?

[Shadow Trader]

The stop check at the end is the most useful line here. On a 100k account, 1 percent risk with a 3 pip EURUSD stop needs about 33 lots, so a 20 lot cap means the stop has to be at least 5 pips to keep the full risk.

Gold is where I hit it in practice. One account capped gold at 5 lots while allowing 20 on FX, and with a $1.20 stop five lots only puts about $600 at risk instead of the $1,000 I planned.

Scaling in caught me once on GBPUSD. I had 12 lots open across three entries, tried to add a fourth at 9 lots, and the order bounced right as price left the level.

Since then I keep a small note beside each symbol with the max lots and the minimum stop that still gives full risk. It takes ten minutes to build and saves arguing with the platform mid trade.

Do you know if most firms count pending orders toward the open lot limit? I have seen it handled both ways and never found it clearly stated in the rules.