about 68% of values fall within 1 SD

85 to 115

These percentages hold only for distributions that are approximately normal. For anything else, or for values that are not a whole number of SDs from the mean, use the z-score and the normal distribution calculator instead.

Steps

  1. 1.1 SD: 100 ± 15 gives 85 to 115 (about 68%)
  2. 2.2 SD: 100 ± 30 gives 70 to 130 (about 95%)
  3. 3.3 SD: 100 ± 45 gives 55 to 145 (about 99.7%)

Empirical rule calculator: 68-95-99.7 intervals · free from StatsLearn