Probability of Touch Calculator
Odds the underlying touches a level before expiry — roughly twice the probability of finishing there, computed exactly.
Formula
By the reflection principle a driftless price that ever reaches a barrier is equally likely to end either side of it — hence touch ≈ 2× finish. Practical upshot: short strikes get tested far more often than expiry deltas suggest; plan management, not hope.
Not financial advice — for informational and analytical use only. Verify all figures with a qualified professional before acting on them.
Need probability of touch calculator results fast? Analysts, founders, traders and finance professionals use the Probability of Touch Calculator to skip the spreadsheet and get a defensible answer in one step — free, private and instant.
About Probability of Touch Calculator
Odds the underlying touches a level before expiry — roughly twice the probability of finishing there, computed exactly. By the reflection principle a driftless price that ever reaches a barrier is equally likely to end either side of it — hence touch ≈ 2× finish. Practical upshot: short strikes get tested far more often than expiry deltas suggest; plan management, not hope. The governing relationship is P(touch) ≈ 2 × P(finish beyond) (reflection principle). The Probability of Touch Calculator computes entirely in your browser — free, private (your figures never leave your device) and instant, recalculating live as you change any input.
How to use Probability of Touch Calculator
- 1Enter Spot price, Level to touch, Implied volatility (%), Days to expiry into the Probability of Touch Calculator.
- 2The result is computed automatically using P(touch) ≈ 2 × P(finish beyond) (reflection principle) — there is no button to press.
- 3Change any input to model a different scenario, then copy or share the result.
Why use Probability of Touch Calculator?
- ✓Computes probability of touch calculator instantly with the correct formula — no spreadsheet needed
- ✓100% free and unlimited, with no sign-up, login or paywall
- ✓Runs entirely in your browser, so the figures you enter stay private
- ✓Shows the formula, a live worked example and references so you can defend the number
Frequently asked questions
What is the formula behind the Probability of Touch Calculator?+
Probability of Touch Calculator uses P(touch) ≈ 2 × P(finish beyond) (reflection principle). By the reflection principle a driftless price that ever reaches a barrier is equally likely to end either side of it — hence touch ≈ 2× finish. The tool substitutes your actual inputs into this relationship and shows the worked example step by step.
What inputs does the Probability of Touch Calculator need?+
Enter Spot price, Level to touch, Implied volatility (%), Days to expiry and the result updates immediately — there is no button to press. Change any value to model a different scenario in real time.
Is the Probability of Touch Calculator free, and is my data private?+
Yes — it is completely free with no sign-up or usage limit, and it runs entirely in your browser, so the numbers you enter are never uploaded or stored on any server. It is for informational and analytical use, not financial advice.
What should I watch out for when using the Probability of Touch Calculator?+
Practical upshot: short strikes get tested far more often than expiry deltas suggest; plan management, not hope.
What is the Probability of Touch Calculator based on?+
The method follows authoritative sources: Shreve — first passage times; reflection principle. The formula and references are shown on the page so you can verify and cite the result.
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