Krejcie & Morgan sample size table calculator
Type your population size and see the minimum sample size straight from the 1970 table — with ready-to-use text for your methodology chapter.
The formula behind the table
Krejcie and Morgan did not collect these numbers empirically: every row is computed from one formula, published with the table in their 1970 article.
s = X²NP(1 − P) ÷ [d²(N − 1) + X²P(1 − P)]
- s = required sample size
- N = population size
- X² = chi-square value for 1 degree of freedom at the chosen confidence level (3.841 for 95%)
- P = population proportion, set to 0.50 to give the largest sample size
- d = degree of accuracy (margin of error), 0.05
Krejcie & Morgan table (short version)
N is the population size and s the minimum sample size at a 95% confidence level. As the population grows, s levels off at 384 and stops increasing.
| Population (N) | Sample size (s) |
|---|---|
| 10 | 10 |
| 30 | 28 |
| 50 | 44 |
| 100 | 80 |
| 150 | 108 |
| 200 | 132 |
| 250 | 152 |
| 300 | 169 |
| 400 | 196 |
| 500 | 217 |
| 600 | 234 |
| 800 | 260 |
| 1,000 | 278 |
| 1,500 | 306 |
| 2,000 | 322 |
| 3,000 | 341 |
| 5,000 | 357 |
| 10,000 | 370 |
| 20,000 | 377 |
| 50,000 | 381 |
| 1,000,000 | 384 |
Source: Krejcie, R. V., & Morgan, D. W. (1970). Determining Sample Size for Research Activities. Educational and Psychological Measurement, 30(3), 607–610.
Plan for a few extra responses
The table gives a minimum. In practice researchers usually collect 10–20% more to cover incomplete or unusable questionnaires.
Frequently asked questions
What is the Krejcie and Morgan table and when should I use it?
The Krejcie & Morgan (1970) table lists the minimum sample size (s) for a known population size (N), with the confidence level fixed at 95% and the margin of error at 5%. It suits survey research where the population is known and finite, such as the staff of an organisation or the students of a faculty. Because it is a published table, it is easy to cite and quick for examiners to check.
How is Krejcie and Morgan different from the Taro Yamane formula?
Both start from the population size (N). Taro Yamane lets you choose the margin of error (for example 1%, 5% or 10%), while Krejcie & Morgan always uses 95% confidence and a 5% margin of error. The results differ slightly: for a population of 1,000, Krejcie & Morgan gives 278 and Taro Yamane at e = 5% gives 286. Both are widely accepted.
What if my population size is not a row in the table?
The original table lists N in steps, such as 100, 110, 120. If your population falls between two rows, for example 105, you can either interpolate between the two rows or use the sample size of the higher row to be on the safe side. This calculator shows the interpolated value and both neighbouring rows.
What sample size do I need for a very large population?
The table levels off at 384 for very large populations (1,000,000 and above). If your population is very large or its exact size is unknown, 384 can serve as the minimum sample size.
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