How do I use SQRT to calculate standard deviation?

SQRT alone does not calculate standard deviation—use STDEV, STDEV.S, or STDEV.P functions instead. However, you can compute root mean square with =SQRT(SUMPRODUCT((range)^2)/COUNT(range)) for advanced statistical workflows.

Why does SQRT return an error for negative numbers?

Because no real number multiplied by itself produces a negative result. If you need to handle negative inputs, use ABS() first: =SQRT(ABS(value)). For complex numbers, spreadsheets do not support imaginary results.

What's the difference between SQRT(16) and POWER(16, 0.5)?

They return the same result (4). SQRT is more readable for square roots, while POWER offers flexibility for other roots: POWER(number, 1/3) calculates cube roots, POWER(number, 1/4) calculates fourth roots, and so on.

How do I round the result of SQRT to a certain number of decimal places?

Nest SQRT inside ROUND: =ROUND(SQRT(1200), 2) returns 34.64 (rounded to 2 decimals). Change the second argument to your desired precision—0 for whole numbers, 3 for three decimals, etc.

SQRT function

Returns the positive square root of a positive number; produces a #NUM! error for negative values or #VALUE! for non-numeric input.

=SQRT(number)

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Describe what you need. The generator will reach for SQRT where SQRT is the right tool, and tell you when it is not.

Arguments

How SQRT reads its arguments

Argument	Required	Description
number	Required	Required. A numeric value; must be non-negative (zero or positive). Negative values return #NUM! error, and text or references to non-numeric cells return #VALUE! error.

Returns

A number representing the principal (positive) square root of the input value.

Availability

Excel: All · Google Sheets: Supported

Worked examples

1. Find the square root of click volume for a campaign

Campaign	Channel	Spend	Clicks	Conversions
Spring Promo	Social	2500	1200	120

=SQRT(1200)

Result: 34.64

The Spring Promo campaign generated 1200 clicks. SQRT(1200) returns approximately 34.64, useful for normalizing metrics in statistical analysis or modeling campaign performance across different scales.

2. Calculate the square root of conversions for a perfect square result

Campaign	Channel	Spend	Clicks	Conversions
Holiday Blast	Search	1600	640	64

=SQRT(64)

Result: 8

The Holiday Blast campaign achieved 64 conversions, which is a perfect square. SQRT(64) returns exactly 8, showing how SQRT cleanly simplifies perfect squares for variance calculations or sample-size estimation.

3. Find the square root of total campaign spend

Campaign	Channel	Spend	Clicks	Conversions
Summer Sale	Email	1200	450	45
Spring Promo	Social	2500	1200	120
Holiday Blast	Search	1600	640	64
Flash Deal	Email	800	320	32
Loyalty Push	Social	950	380	38

=SQRT(SUM(C2:C6))

Result: 76.87

Total spend across all five campaigns is 7050. SQRT(7050) returns approximately 76.87, commonly used in statistical adjustments, confidence interval calculations, or normalizing aggregated campaign budgets.

Common errors

Which SQRT error are you seeing?

Error	Why it happens	How to fix it
#NUM!	Passing a negative number to SQRT, such as SQRT(-2500) when a calculation or cell reference resolves to a negative value.	Ensure the input is non-negative. Use ABS() to convert: =SQRT(ABS(number)), or check the upstream calculation that produced the negative result.
#VALUE!	Passing text or a reference to a text cell, such as =SQRT(B2) when B2 contains 'Social' or =SQRT('Email').	Verify the input cell contains only a number. If the cell holds a text representation of a number, convert it: =SQRT(VALUE(B2)).
#REF!	Referencing a cell or column that was deleted after the formula was entered, such as =SQRT(C2) if column C was removed.	Recreate the formula with the correct cell reference, or undo the deletion (Ctrl+Z on Windows, Cmd+Z on Mac) to restore the column.

Tips and when to use something else

SQRT always returns the positive root. For calculations needing both ±√n, combine with conditional logic: =IF(condition, SQRT(n), -SQRT(n)).
To calculate variance or standard deviation properly, use STDEV or STDEV.S instead of manually combining SQRT with SUM—they handle the mathematics correctly and more efficiently.
Perfect squares (4, 9, 16, 25, 64, 100, 2500) return clean integers; all others return decimals. Wrap with ROUND() to clean up: =ROUND(SQRT(1200), 2) returns 34.64.
For root-mean-square calculations in statistical analysis, combine SQRT with SUMPRODUCT: =SQRT(SUMPRODUCT((range)^2)/COUNT(range)).

Related functions

SUMSQSUMSQ returns the sum of the squares of its arguments, useful for statistical analysis and variance calculations.SUMPRODUCTSUMPRODUCT multiplies arrays element-by-element and sums the results, useful for weighted totals and multi-criteria counting.ROUNDROUND returns a number rounded to a specified number of decimal places, using standard rounding rules (0.5 rounds up).ABSABS returns the absolute value of any number, removing the sign to show only magnitude, useful for comparing distances regardless of direction.

Frequently asked questions

How do I use SQRT to calculate standard deviation?: SQRT alone does not calculate standard deviation—use STDEV, STDEV.S, or STDEV.P functions instead. However, you can compute root mean square with =SQRT(SUMPRODUCT((range)^2)/COUNT(range)) for advanced statistical workflows.
Why does SQRT return an error for negative numbers?: Because no real number multiplied by itself produces a negative result. If you need to handle negative inputs, use ABS() first: =SQRT(ABS(value)). For complex numbers, spreadsheets do not support imaginary results.
What's the difference between SQRT(16) and POWER(16, 0.5)?: They return the same result (4). SQRT is more readable for square roots, while POWER offers flexibility for other roots: POWER(number, 1/3) calculates cube roots, POWER(number, 1/4) calculates fourth roots, and so on.
How do I round the result of SQRT to a certain number of decimal places?: Nest SQRT inside ROUND: =ROUND(SQRT(1200), 2) returns 34.64 (rounded to 2 decimals). Change the second argument to your desired precision—0 for whole numbers, 3 for three decimals, etc.

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Reviewed 2026-09-17