A daily loss limit is a pre-set dollar amount that, when your session P&L hits it, ends your trading for the day — no exceptions, no “one more to get it back.” It's the master circuit breaker of a discretionary trading plan, and arguably the single most protective rule a scalper can adopt (it's the first of the red-day rules).
Why you need one
Individual-trade stops cap the damage per trade; they don't cap the damage from a sequence of trades taken in a spiral. After a couple of losses, the urge to “make it back” drives revenge trades, size creep, and forced setups — exactly when you're least able to trade well. The daily loss limit removes that decision from the moment you can't be trusted to make it: hit the number, you're done, walk away.
How to set it
Base it on your risk unit: a common frame is 2–3× your per-trade risk (so 2–3 stopped trades ends the day) or a fixed percent of the account (say 3–5%). Set it before the session, when you're calm, and make it a hard rule, not a suggestion. The exact number matters less than that it exists and that you honor it.
A per-trade stop caps one mistake. A daily loss limit caps the string of mistakes that a mistake tends to trigger. You need both.
Honoring it is the hard part
The limit only works if you obey it — and the moment it's hit is the moment you'll most want to override it (“just one good trade”). Pre-commit: some traders physically close the platform, some hand size control to a rule. This is where automation helps structurally — NoVo's default-Stop and boundary enforcement mean a hit limit can actually halt trading, rather than relying on the willpower you've just proven you don't have. Pair it with a daily profit lock and the two-strikes rule for a complete session-level guardrail.