What the tool does, how to run it, and what to expect from the result.
Cochran’s formula: n₀ = z² × p(1 − p) ÷ e². At 95% confidence (z = 1.96), p = 50% and a ±5% margin: 1.96² × 0.25 ÷ 0.0025 = 384.2, so 385 responses. For a small population N, correct it: n = n₀ ÷ (1 + (n₀ − 1) ÷ N). From 1,000 people you need 278.
A quick way to understand who this helps, what it solves, and where it connects next.
Students, lab workers, electricians and engineers who want the formula and the answer.
Using the sample size calculator without installing anything or signing up.
Short answers for the questions people usually have before trying a utility like this.
It gives the largest sample, so it is the safe choice when you do not know the answer in advance.
No. Above about 20,000 the required sample barely changes: 385 covers a city or a country at 95% ±5%.
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Enter your numbers and the result updates live in your browser. Nothing is uploaded and no server is used.
Calculations run locally in your browser; nothing is uploaded.