Free trader tools
Calculators for the rules and the arithmetic of day trading US small caps. Free, with nothing to sign up for.
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LULD band calculator
The limit up-limit down bands for a price, tier, date and time, including when the doubled closing band applies and how that rule changed in 2020.
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SSR (Rule 201) calculator
The price that puts a stock on the short sale restriction, whether it has triggered, and the trading days it lasts.
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Position size calculator
Shares to trade from your account, risk per trade, entry and stop, with the dollar risk, the R multiple to your target and a buying-power check.
Who they are for
Day traders in US small caps who would rather have a rule worked out than remembered in the middle of a move: where a running stock will pause, whether a short now has to wait above the bid, and how many shares a stop allows. They run in your browser, and nothing you type is sent anywhere.
The LULD band calculator answers where a stock's limit up-limit down bands sit and whether the doubled band applies, under the rule in force on the date you pick, so a past day is worked out under that day's rule. The SSR calculator answers at what price the short sale restriction triggers and which trading days it covers. The position size calculator answers how many shares to trade for the risk you set, what a stop-out costs and whether the position is bigger than your account.
Practice on a real past day in Hindsight Markets
Hindsight Markets replays real market days, every trade and every quote, with LULD bands and SSR applied under that day's rules. You trade it by hand with simulated money.