Campaign success, solved.
Open this calculator as an editable Google Sheet — your inputs and live formulas, ready to fork.
A campaign is many attempts against a goal — emails sent, experiments run, pitches made — and it succeeds if enough of them land. This free calculator computes the real probability of getting at least the wins you need across a set number of attempts, from the per-attempt success rate.
How to calculate campaign success probability
Probabilities of independent attempts don't add — a 1% chance tried 100 times is not 100%. Each attempt either lands (probability p) or misses (1 − p), so the number of wins across n attempts follows a binomial distribution. The campaign succeeds if wins reach your goal k, and that probability is 1 minus the chance of finishing with k − 1 wins or fewer: P = 1 − Σ C(n,i) p^i (1 − p)^(n−i), summed from i = 0 to k − 1. When one win is enough, this collapses to the classic form 1 − (1 − p)^n.
How to read the result
Campaign success and expected wins are different quantities, and the gap between them is where planning goes wrong. Attempts × probability gives the average number of wins — but a campaign that expects exactly its goal on average misses it roughly half the time. If the success probability reads below your risk tolerance, there are only two levers: more attempts, or better per-attempt odds. The curve flattens as volume grows, so past a point improving the per-attempt rate is worth more than adding sends.
Worked example
Suppose a rep books a meeting from about 2% of cold emails and needs 5 meetings this quarter. Across 500 emails the expected number of meetings is 10 — comfortably above 5 — and the binomial math puts the chance of reaching at least 5 at about 97%. Cut the volume to 250 emails and expected meetings drop to 5, exactly the goal, but the chance of actually hitting it falls to roughly 56% — a near coin flip. Planning to the average leaves half the outcomes short of it.
Frequently asked questions
- If I have a 1% chance of success and try 100 times, what are my odds?
- About 63.4%, not 100%. The chance that all 100 attempts fail is 0.99^100 ≈ 36.6%, so the chance of at least one success is 1 − 0.99^100 ≈ 63.4%.
- How do you calculate the probability a campaign hits its goal?
- Model wins as a binomial distribution: n attempts, each succeeding with probability p. The chance of at least k wins is 1 minus the binomial CDF at k − 1 — in a spreadsheet, 1 − BINOMDIST(k−1, n, p, TRUE).
- Why can't I just multiply the probability by the number of attempts?
- Attempts × probability gives the expected number of wins, which is a different quantity from the chance of hitting a goal. Expected wins can equal your goal exactly while the chance of actually reaching it sits near 50% — and probabilities added this way would eventually exceed 100%, which is impossible.
- How many attempts does a campaign need to be safe?
- Enough that the at-least-k probability clears your risk tolerance — 90% is a common planning bar. As a rule of thumb that means volume well above the break-even point where expected wins equal the goal; the calculator solves the exact number for your inputs.