Determining Sample Size

The size of the population and the amount of error the researcher is willing to tolerate is what determines the size of the sample. The table that follows was developed for situations where the researcher wants to come within 5 percentage points (with 95 percent certainty) of what the results would have been if the entire population had been surveyed. A more flexible approach is to use a sample size calculator that allows you to enter your preferences.

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Table for Determining the Needed Size of a Randomly Chosen Sample from a Given Finite Population

Population	Sample	|	|	Population	Sample	|	|	Population	Sample
10	10			220	140			1200	291
15	14			230	144			1300	297
20	19			240	148			1400	302
25	24			250	152			1500	306
30	28			260	155			1600	310
35	32			270	159			1700	313
40	36			280	162			1800	317
45	40			290	165			1900	320
50	44			300	169			2000	322
55	48			320	175			2200	327
60	52			340	181			2400	331
65	56			360	186			2600	335
70	59			380	191			2800	338
75	63			400	196			3000	341
80	66			420	201			3500	346
85	70			440	205			4000	351
90	73			460	210			4500	354
95	76			480	214			5000	357
100	80			500	217			6000	361
110	86			550	226			7000	364
120	92			600	234			8000	367
130	97			650	242			9000	368
140	103			700	248			10 000	370
150	108			750	254			15 000	375
160	113			800	260			20 000	377
170	118			850	265			30 000	379
180	123			900	269			40 000	380
190	127			950	274			50 000	381
200	132			1000	278			75 000	382
210	136			1100	285			1 000 000	384
Population	Sample	|	|	Population	Sample	|	|	Population	Sample

Krejcie, R. V., & Morgan, D. W. (1970). Determining sample size for research activities. Educational and Psychological Measurement, 30, 607-610.

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Del Siegle, Ph.D.
Neag School of Education – University of Connecticut
del.siegle@uconn.edu
www.delsiegle.com