# How to calculate a cube root in Excel

Raise the number to the power of one third, `=B2^(1/3)`, and use 1/n for any nth root.

**Excel:** `=B2^(1/3)` (Every current version)

**Google Sheets:** the same formula works.

## Example

Sample data (row 1 is the header):

| A | B | C |
| --- | --- | --- |
| Tank | Volume (cu ft) | Edge length (ft) |
| A | 27 |  |
| B | 64 |  |
| C | 100 |  |
| D | 8 |  |
| E | 343 |  |

Formula in C2, filled to C6: `=B2^(1/3)`

Result: 3.00; 4.00; 4.64; 2.00; 7.00

## How it works

Excel has no CBRT function, but a cube root is the power 1/3: 3 × 3 × 3 = 27, so `27^(1/3)` is 3. The parentheses matter, because `^` is calculated before division.

## Other ways

- `=POWER(B2,1/3)`: POWER is the function form of the same calculation.

## Common mistakes

- `=B2^1/3` without parentheses means (B2^1)/3: 27 becomes 9.
- A negative number to a fractional power returns #NUM! in Excel, even though -8 has the cube root -2. Use `=SIGN(B2)*ABS(B2)^(1/3)`.

## Questions

**How do I calculate any nth root?**

Use `=B2^(1/n)`, for example `=B2^(1/4)` for a fourth root.

**Why does the result show 3.9999999999?**

Powers are calculated in binary, so roots can be off in the 15th digit. Wrap in ROUND if you compare results: `=ROUND(B2^(1/3),10)`.

Every formula and result on this page was checked by running it in the Spreadsheet Practice formula engine on 2026-10-30.

Source: https://spreadsheetpractice.com/formulas/cube-root