Summary

The Excel SQRT function returns the positive square root of a number. If a value multiplied by itself produces the original number, SQRT returns that value. For example, =SQRT(25) returns 5 because 5 multiplied by 5 equals 25.

SQRT returns only the principal square root, which means the non-negative result. It does not return both algebraic roots. The input must also be non-negative. If the argument is negative, Excel returns #NUM! because standard worksheet SQRT operates in the real-number domain rather than complex numbers.

Syntax

=SQRT(number)

SQRT has one required argument: the number whose square root you want. That argument can be a literal, a cell reference, or any formula that evaluates to a non-negative number. When the intent is specifically "take the square root," SQRT is usually clearer than writing the same operation as an exponent.

Arguments

• number - [Required] The non-negative value whose square root should be returned.

SQRT vs Other Functions

SQRT overlaps with exponentiation functions, but it has a narrower and more explicit purpose. When the operation is specifically a square root, SQRT communicates that intent immediately.

SQRT is not broader than exponentiation, but it is more explicit. That matters in shared workbooks because readability is often more valuable than compactness, especially in technical formulas that will be maintained later by another analyst.

Using SQRT

SQRT appears naturally in geometry. If the area of a square is known, the side length is the square root of that area. The function also appears in coordinate geometry, where the Euclidean distance between two points is derived by squaring coordinate differences, summing them, and then taking the square root of the result.

It also surfaces in statistical work because many measures are built from squared deviations. Standard deviation, for example, is conceptually the square root of variance. Excel offers dedicated statistical functions for those tasks, but understanding SQRT helps when you need to build or inspect the underlying calculation structure.

• Use SQRT(area) to derive the side length of a square from its area.
• Use SQRT(POWER(x2-x1,2)+POWER(y2-y1,2)) for straight-line distance in two dimensions.
• Use SQRT on intermediate formula results when the model produces a squared quantity that must be converted back to its original scale.

Example 1 - Find the Square Root of a Number

This is the direct use of the function. SQRT returns the principal square root of the input and does not evaluate alternative signed roots. For worksheet calculations, that means the result is always non-negative as long as the input itself is valid.

=SQRT(25)   // 5
=SQRT(2)    // about 1.41421356
=SQRT(B1)   // square root of the value in B1

Example 2 - Find the Side Length from a Known Area

If a square has area 144, its side length is the value that produces 144 when squared. SQRT reverses that relationship directly. This pattern appears in geometry, layout work, and any model where an area must be translated back into a linear dimension.

=SQRT(B2)
// B2 = 144
// Result = 12

Example 3 - Calculate Distance Between Two Points

This formula applies the Pythagorean theorem. The coordinate differences are squared to remove direction, added together, and then square-rooted to return the straight-line distance. It is a standard pattern in geometric and engineering-style models.

=SQRT(POWER(B4-B3,2)+POWER(C4-C3,2))
// (0,0) to (3,4)
// SQRT(3^2 + 4^2) = SQRT(25) = 5

Example 4 - Take the Square Root of a Calculated Value

SQRT does not need a direct cell input. It can be applied to any formula result, which makes it useful in larger expressions. In this example, the sum is evaluated first, and SQRT converts that total into its square root afterward.

=SQRT(B5+C5)
// B5 = 8, C5 = 17
// 8 + 17 = 25
// SQRT returns 5

When negative inputs are possible, decide whether the model should reject them or transform them before calling SQRT. Using SQRT(ABS(A1)) may be appropriate when only magnitude matters, but it also changes the mathematical meaning of the calculation. In models where the sign carries meaning, it is usually better to handle the negative case explicitly instead of masking it.

• SQRT(0) returns 0.
• Negative input returns #NUM!.
• Use a dedicated complex-number function such as IMSQRT when imaginary results are intentional.

Conclusion Recap

• Summary: SQRT returns the positive square root of a non-negative number.
• Syntax: =SQRT(number) with one required argument.
• Key behavior: The result is always the principal square root, and negative input returns #NUM!.
• Practical usage: Geometry, distance formulas, and calculations derived from squared quantities.