How to Do Cube Root in Excel

Q: How do I do a cube root in Excel?

Use either =number^(1/3) or =POWER(number,1/3). For example, =64^(1/3) and =POWER(64,1/3) both return 4. Replace number with a cell reference such as A1 to root the value in that cell. Both formulas behave identically on Windows and Mac.

Q: Is there a cube root function in Excel?

No. Excel has no CUBEROOT function and no dedicated cube-root command of any kind. It does include SQRT for square roots, but for cube roots you must use the exponent operator ^(1/3) or the POWER function. Anyone telling you to type =CUBEROOT(...) is mistaken — that formula returns a #NAME? error.

Q: What is the Excel cube root formula?

The cube root formula is =A1^(1/3), which raises the number in A1 to the power of one-third. The equivalent function-based version is =POWER(A1,1/3). Always keep the parentheses around 1/3, or Excel's order of operations will divide instead of root.

Q: Why does my cube root return a #NUM! error?

Excel returns #NUM! when you take the cube root of a negative number with a fractional exponent, because it won't raise a negative base to a fractional power. Use =SIGN(A1)ABS(A1)^(1/3) instead: it roots the absolute value, then restores the original sign, so −8 correctly returns −2.

Q: How do I find the cube root of a negative number in Excel?

Use =SIGN(A1)ABS(A1)^(1/3). The ABS function removes the minus sign, the exponent takes the cube root of the positive value, and SIGN puts the negative sign back. The direct formula =(-8)^(1/3) will not work — it produces a #NUM! error every time.

To find a cube root in Excel, use the exponent operator =A1^(1/3) or the equivalent =POWER(A1,1/3), where A1 holds your number. Both raise the value to the power of one-third, which is the mathematical definition of a cube root, and both work identically on Windows and Mac.

There is no CUBEROOT function in Excel. Excel ships a dedicated SQRT function for square roots, but it has no built-in equivalent for cube roots or any higher root, so you build them from exponents instead. The good news is that the exponent approach is more flexible anyway: the same pattern handles cube roots, fourth roots, and any nth root you need.

The two ways to calculate a cube root

Both methods below return the same answer. Pick whichever reads more clearly to you.

Method 1 — the exponent operator (^). The caret ^ raises a number to a power. Because raising to the power of 1/3 is the same as taking the cube root, this formula does the job:

=27^(1/3)

This returns 3, because 3 × 3 × 3 = 27. To reference a cell instead of a hard-coded number, use =A1^(1/3).

Method 2 — the POWER function. POWER does exactly what the ^ operator does, just in function form. Its syntax is POWER(number, power):

=POWER(125, 1/3)

This returns 5, because 5 × 5 × 5 = 125. With a cell reference it becomes =POWER(A1, 1/3). For a deeper look at the function’s arguments, see our guide to the POWER function in Excel. The ^ operator and POWER are interchangeable for this task, much like the relationship between SQRT and ^(1/2) covered in our square root in Excel walkthrough.

Step-by-step

Click an empty cell where you want the answer to appear.
Type =POWER(A1,1/3) (or =A1^(1/3)), replacing A1 with the cell holding your number.
Press Enter. The cube root appears immediately.

Worked examples

Number	Formula	Result	Check (result³)
27	`=27^(1/3)`	3	3 × 3 × 3 = 27
64	`=POWER(64,1/3)`	4	4 × 4 × 4 = 64
125	`=125^(1/3)`	5	5 × 5 × 5 = 125
216	`=POWER(216,1/3)`	6	6 × 6 × 6 = 216
1000	`=1000^(1/3)`	10	10 × 10 × 10 = 1000

The fastest way to verify any cube root is to cube the result and confirm you get the original number back. The cube root of 27 is 3, and 3 cubed is 27 — so the formula is right.

Method comparison

Approach	Formula	Best for	Notes
Exponent operator	`=A1^(1/3)`	Quick, compact entry	Parentheses around `1/3` are essential
POWER function	`=POWER(A1,1/3)`	Readability, nesting in bigger formulas	Same result as `^`, more self-documenting
SQRT (square root only)	`=SQRT(A1)`	Square roots, not cube roots	No cube-root equivalent exists

The general nth root

Once you understand cube roots, every other root follows the same rule: the nth root of a number is that number raised to the power of 1/n. So divide 1 by the root you want and plug it in.

=A1^(1/n)     or     =POWER(A1, 1/n)

Cube root (n = 3): =A1^(1/3)
Fourth root (n = 4): =A1^(1/4) → the fourth root of 81 is 3
Fifth root (n = 5): =A1^(1/5) → the fifth root of 32 is 2

To make a flexible worksheet, put the root in its own cell — say B1 holds the number and B2 holds the value of n — then write =B1^(1/B2). Now you can change the root without touching the formula. If fractional exponents feel unfamiliar, our primer on exponents in Excel covers the underlying math, and the broader Excel math functions guide places roots in context with the rest of Excel’s numeric toolkit.

The negative-number trap

This is where most people get stuck. Mathematically, the cube root of −8 is −2, because (−2) × (−2) × (−2) = −8. But if you type the direct formula:

=(-8)^(1/3)

Excel returns the #NUM! error. Excel treats a fractional exponent as a request for a real-number power, and it refuses to raise a negative base to a fractional power, even though an odd root like the cube root is perfectly valid for negatives.

The workaround is to take the cube root of the absolute value and then re-apply the original sign:

=SIGN(A1)*ABS(A1)^(1/3)

With A1 set to −8, ABS(A1) strips the minus sign to give 8, 8^(1/3) returns 2, and SIGN(A1) returns −1, so the product is −2 — the correct cube root. SIGN returns −1, 0, or 1 depending on whether the number is negative, zero, or positive, and the ABS function returns the magnitude without the sign. This pattern works for any odd root (cube, fifth, seventh); even roots of negative numbers have no real answer and a #NUM! is appropriate there.

Filling the formula down a column

To cube-root an entire column of numbers, you only write the formula once:

Enter =A2^(1/3) next to your first number in cell B2.
Select B2 and hover over the small square in its bottom-right corner — the fill handle.
Double-click the fill handle (or drag it down) to copy the formula to every adjacent row.

The relative reference A2 shifts automatically to A3, A4, and so on as it fills. If you need to point every formula at one fixed cell — for example, a single n value for the nth root — lock that reference with dollar signs, like =A2^(1/$B$1). Our drag a formula down tutorial covers the fill handle and absolute references in more detail.

Rounding the result

Many cube roots are irrational and display a long string of decimals — the cube root of 30 is roughly 3.107232506. To trim it to a tidy number of decimal places, wrap the formula in ROUND:

=ROUND(A1^(1/3), 2)

The second argument is the number of decimal places, so this returns 3.11. Keep in mind that ROUND changes the stored value, not just the display, so it will affect any later calculations that reference the cell. See our guide to rounding numbers in Excel for ROUNDUP, ROUNDDOWN, and how they differ from cell formatting.

Troubleshooting

#NUM! error. Almost always a negative input combined with a fractional exponent. Use the =SIGN(A1)*ABS(A1)^(1/3) workaround above. Double-check the cell isn’t formatted as text, which can also block the math.

Wrong answer because of order of operations. The parentheses around 1/3 are not optional. Without them, =27^1/3 is read as “27 to the power of 1, then divided by 3” — which evaluates to 9, not 3. Excel applies exponentiation before division, so you must group the fraction yourself: =27^(1/3).

Result is slightly off — e.g. 3.0000000004 instead of 3. This is floating-point rounding, an inherent limit of how all spreadsheet software stores decimals, not a mistake in your formula. The cube root of 27 may come back as a value microscopically different from 3. Wrap it in ROUND to clean up the display, or read our explainer on fixing rounding errors in Excel if the tiny differences are breaking downstream comparisons.

#VALUE! error. The referenced cell contains text rather than a number. Confirm the input is numeric.

Frequently Asked Questions

How do I do a cube root in Excel?

Use either =number^(1/3) or =POWER(number,1/3). For example, =64^(1/3) and =POWER(64,1/3) both return 4. Replace number with a cell reference such as A1 to root the value in that cell. Both formulas behave identically on Windows and Mac.

Is there a cube root function in Excel?

No. Excel has no CUBEROOT function and no dedicated cube-root command of any kind. It does include SQRT for square roots, but for cube roots you must use the exponent operator ^(1/3) or the POWER function. Anyone telling you to type =CUBEROOT(...) is mistaken — that formula returns a #NAME? error.

What is the Excel cube root formula?

The cube root formula is =A1^(1/3), which raises the number in A1 to the power of one-third. The equivalent function-based version is =POWER(A1,1/3). Always keep the parentheses around 1/3, or Excel’s order of operations will divide instead of root.

How do I calculate the nth root in Excel?

The nth root of a number is the number raised to the power of 1/n, so the formula is =A1^(1/n) or =POWER(A1,1/n). For a fourth root use ^(1/4), for a fifth root use ^(1/5), and so on. You can store n in its own cell — for example =A1^(1/B1) — to switch roots without rewriting the formula.

Why does my cube root return a #NUM! error?

Excel returns #NUM! when you take the cube root of a negative number with a fractional exponent, because it won’t raise a negative base to a fractional power. Use =SIGN(A1)*ABS(A1)^(1/3) instead: it roots the absolute value, then restores the original sign, so −8 correctly returns −2.

How do I find the cube root of a negative number in Excel?

Use =SIGN(A1)*ABS(A1)^(1/3). The ABS function removes the minus sign, the exponent takes the cube root of the positive value, and SIGN puts the negative sign back. The direct formula =(-8)^(1/3) will not work — it produces a #NUM! error every time.