Formulas Used by the Calculator

IndiKit's Sample Size Calculator is based on the following formulas:

ss = sample size

Z = Z value (1.96 for a 95% confidence level)

p = percentage picking a choice or response (the calculator uses 0.5)

c = confidence interval, expressed as a decimal (e.g. 0.05 = ±5)

pop = your survey’s target population

IndiKit's Margin of Error Calculator is based on the following formulas:

If the population size is entered, the calculation is based on the following formula:

Z = Z value (1.96 for a 95% confidence level) 

p = percentage picking a choice or response (the calculator uses 0.5)

n = sample size

N = population size

If the population size is not specified, the calculation is based on the following formula:

Z = Z value (1.96 for a 95% confidence level) 

p = percentage picking a choice or response (the calculator uses 0.5)

n = sample size