If you want to know how much your numbers vary around their average, the STDEV function in Google Sheets gives you that spread in one step. It returns the sample standard deviation, which tells you whether your values cluster tight or scatter wide.
In this article, I’ll show you how STDEV works, walk through five practical examples, and flag a couple of things to watch for.
STDEV Function Syntax in Google Sheets
The STDEV function takes one or more numbers or ranges.
=STDEV(value1, [value2, ...])
- value1 is the first number or range to include in the calculation.
- value2, … are optional extra numbers or ranges to add to the same sample.
STDEV treats your data as a sample, not the whole population. That’s the version you want most of the time.
When to Use STDEV Function
Here are a few times STDEV comes in handy.
- Measuring how consistent a set of test scores or survey results is.
- Checking the variation in repeated lab readings or sensor measurements.
- Spotting whether daily sales swing a lot or stay steady.
- Comparing the spread of one group against another in the same dataset.
Example 1: Standard Deviation of a Column of Scores
Let’s start with the most common use.
Below is the dataset, with student names in column A and their test scores in column B.
The goal is to measure how spread out the six scores are.
Here is the formula:
=STDEV(B2:B7)
STDEV takes all six scores, finds their average, then measures how far each score sits from that average. The result is about 10.72, which says the scores swing a fair bit around the mean.
Example 2: Spread of Repeated Measurement Readings
STDEV is great for checking how consistent a set of readings is.
Below is the dataset, with a trial number in column A and a measured reading in column B.
The goal is to see how tightly the five readings agree with each other.
Here is the formula:
=STDEV(B2:B6)
The readings all sit close to 10, so the spread is small. STDEV gives a standard deviation of about 0.27, which confirms the measurements are consistent.
Pro Tip: A small standard deviation means your values bunch close to the average. A large one means they scatter. The unit is the same as your data, so 0.27 here is 0.27 of a reading.
Example 3: Standard Deviation Across Two Columns Combined
You can hand STDEV more than one range at a time.
Below is the dataset, with a day in column A, sales for Store A in column B, and sales for Store B in column C.
The goal is to measure the spread of all ten sales numbers as one combined sample.
Here is the formula:
=STDEV(B2:B6,C2:C6)
STDEV pools both columns into a single set of ten values and measures the spread across all of them. The result is about 10.45.
Pro Tip: You can pass STDEV any mix of ranges and single numbers. Separate each one with a comma and they all join the same sample.
Example 4: Standard Deviation of a Filtered Subset
Sometimes you only want the spread for one group inside a bigger table.
Below is the dataset, with a score in column A and a group label in column B.
The goal is to measure the spread of the Group A scores only, skipping Group B.
Here is the formula:
=STDEV(FILTER(A2:A7,B2:B7="A"))
How this formula works:
- FILTER keeps only the scores where column B equals “A”, which leaves four values.
- STDEV then measures the spread of just those four Group A scores.
- The result is about 6.06, lower than the spread of the full mixed set would be.
Example 5: Text in the Range Is Ignored Automatically
This last one shows a handy bit of forgiving behavior.
Below is the dataset, with an item in column A and a weight in column B, where the final row holds the text “n/a” instead of a number.
The goal is to measure the spread of the weights without that text label tripping things up.
Here is the formula:
=STDEV(B2:B7)
STDEV simply skips the “n/a” text and works with the five numeric weights. The result is about 5.87, exactly what you’d get if the text cell weren’t there.
Tips & Common Mistakes
- STDEV is the sample version, not the population one. If your data covers the entire population rather than a sample, use STDEVP instead. The two give slightly different numbers.
- You need at least two numbers. STDEV measures spread, so a single value returns a divide-by-zero error. Make sure your range holds two or more numeric entries.
- Text and blank cells are skipped, not counted as zero. This is usually what you want, but it means an empty cell won’t drag your spread down the way a literal 0 would.
STDEV gives you the sample standard deviation of one or more ranges, telling you how far your numbers stray from their average. You saw it handle a single column, repeated readings, two columns at once, a filtered group, and a stray text label.
Keep the sample-versus-population distinction in mind and it’s a quick way to measure how steady or scattered your data is.
List of All Google Sheets Functions
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