Relative Standard Deviation Calculator

Find the relative standard deviation (RSD) of a data set.

Value 1

Value 2

Value 3

Value 4

Value 5

Relative SD (%) 1.581

Standard deviation 0.1581

Formula: RSD = SD ÷ mean × 100

Step-by-step with your numbers:

1. Values used:

2. Value 1 = 9.8

3. Value 2 = 10.1

4. Value 3 = 9.9

5. Value 4 = 10.2

6. Value 5 = 10

8. Relative SD = 1.581%

9. Standard deviation = 0.1581

Did we solve your problem today?

RSD expresses the standard deviation as a percentage of the mean — often used in lab quality control.

The math behind it

RSD = (SD ÷ mean) × 100. It's the same as the coefficient of variation.

Lab replicates near 10 → RSD ≈ 1.6%.

What's a good RSD?

In analytical chemistry, under ~2% usually indicates good precision.