Sample Size Calculator

Calculate required sample size for surveys from population, confidence level, and margin of error.
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%

Required Sample

370

Infinite Pop.

385

Parameters

Sample Size (finite pop.)370
Sample Size (infinite pop.)385
Z-value1.960
Margin of Error5.0%
Proportion50.0%

Use the Sample Size Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

This Sample Size Calculator helps you determine the minimum number of respondents needed for your survey to be statistically significant, ensuring your results accurately reflect the target population. In 2026, with an increasing emphasis on data-driven decisions across industries like AI development and climate research, obtaining a reliable sample size is crucial for valid insights.

The calculation uses the formula for sample size when the population proportion is unknown, which is n = (Z^2 * p * (1-p)) / E^2, where 'n' is the sample size, 'Z' is the Z-score for the desired confidence level, 'p' is the estimated population proportion (often set at 0.5 for maximum variability), and 'E' is the margin of error. For finite populations, a correction factor is applied.

A common mistake is assuming a larger population always requires a significantly larger sample; beyond a certain point, the required sample size plateaus. Be mindful of your confidence level and margin of error; a higher confidence or lower margin of error will necessitate a larger sample, which can increase survey costs and time.

Example: 2026 Global AI Adoption Survey

  1. 1 Imagine you're conducting a global survey in 2026 to understand the adoption rate of new AI technologies among businesses. Your target population is 500,000 businesses worldwide. You want to be 95% confident in your results with a 3% margin of error.
  2. 2 Using the calculator, you would input: Population Size = 500,000, Confidence Level = 95%, and Margin of Error = 3%. The calculator applies the Z-score for 95% confidence (1.96) and assumes a population proportion (p) of 0.5.
  3. 3 The calculated sample size required for your survey would be approximately 1067 businesses.
  4. 4 This means you need to survey at least 1067 businesses to be 95% confident that the actual global AI adoption rate among businesses falls within +/- 3% of your survey's findings. This sample size is relatively small compared to the large population, demonstrating the power of statistical sampling for accurate insights.

Source: Khan Academy · Last updated: April 2026

Frequently Asked Questions

How many survey responses do I need?
For a population of 10,000+ with 95% confidence and 5% margin of error, you need about 385 responses. For a 3% margin of error, you need about 1,068. Smaller populations require fewer responses.
What affects required sample size?
Three factors: confidence level (higher = larger sample), margin of error (smaller = larger sample), and population variability (more variable = larger sample). Doubling precision quadruples the required sample size.
What is a good margin of error for a survey?
A 3-5% margin of error is standard for most surveys. Political polls often use 3%. Market research is acceptable at 5-7%. Anything above 10% has limited reliability for making decisions.

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