Every calculator on PreBreakout is deterministic: the same valid inputs produce the same output. The launch version does not retrieve securities prices or market history. Calculator inputs are processed in the browser.
Core principles
- User-defined inputs: the site does not choose entry, stop, target, risk percentage, ATR multiplier or reference levels for you.
- Visible formulas: each calculator displays its governing formula and a worked fictional example.
- No hidden score: outputs are not converted into “good”, “bad”, “strong”, “weak”, “buy” or “sell” labels.
- No probability inference: geometric ratios are not presented as success probabilities.
Validation rules
Inputs that would make a formula undefined or logically inconsistent are rejected. Examples include division by zero, a drawdown of 100%, a range high that is not above its low, or a long risk/reward model in which the stop is above the entry.
Rounding
Displayed values are rounded for readability, but calculations use JavaScript number precision before formatting. Position size is rounded down to a whole unit because the calculator’s stated model is a whole-unit count. This does not imply that a broker does or does not support fractional units.
What is omitted
Unless a calculator explicitly contains a cost input, results do not model commissions, spread, slippage, financing, taxes, margin requirements, liquidity, order priority, gaps, corporate actions or broker-specific rules.
Formula register
Reward-to-risk: |target − entry| ÷ |entry − stop|.
Position size: (account value × chosen risk %) ÷ |entry − stop|.
Measured move: pattern height = high − low; projected level = breakout ± height.
ATR distance: ATR × user-entered multiplier.
Drawdown recovery: (1 ÷ (1 − drawdown)) − 1.
Break-even win rate: 1 ÷ (1 + reward-to-risk).
Expectancy: (win rate × average win) − (loss rate × average loss).
Percentage change: (end − start) ÷ start × 100.
Weighted average: Σ(quantity × value) ÷ Σquantity.
Volume ratio: observed volume ÷ reference average volume.
Additional formula register
Stop distance and modeled loss: |entry − stop|; modeled loss = stop distance × quantity.
Maximum drawdown: for each ordered observation, compare the value with the highest value seen up to that point; the largest percentage decline from a running peak is the maximum drawdown.
Series handling: the maximum-drawdown calculator accepts up to 500 positive observations separated by commas, spaces, semicolons or line breaks. Ordering is preserved because drawdown is path-dependent.
Profit factor formula
Profit factor: gross profit ÷ gross loss, using positive gross-loss magnitude from the same sample and same units. If gross loss is zero, the finite ratio is undefined and the calculator returns a validation message instead of infinity.
Observed win-rate formula
Observed win rate: wins ÷ (wins + losses) × 100. PreBreakout excludes explicitly break-even outcomes from the primary denominator and separately reports wins as a share of all closed outcomes. Counts must be non-negative whole numbers, and at least one win or loss is required.