TRUNC()
Removes the fractional part of a number, without rounding.
TRUNC(number, [num_digits])TRUNC cuts off the decimal portion of a number to leave the specified number of digits, always moving toward zero rather than rounding to the nearest value.
With num_digits omitted or 0, TRUNC behaves like chopping off everything after the decimal point. This differs from INT, which rounds down toward negative infinity: for negative numbers, TRUNC and INT give different results, since TRUNC(-8.9) is -8 but INT(-8.9) is -9.
A positive num_digits keeps that many decimal places (still truncated, not rounded); a negative num_digits truncates digits to the left of the decimal point.
Arguments
- number
- The number to truncate.
- num_digitsoptional
- How many decimal places to keep. Default is 0.
Examples
=TRUNC(8.9)The decimal portion is simply dropped, not rounded up.
=TRUNC(-8.9)Truncates toward zero, unlike INT(-8.9) which returns -9.
TRUNC tricks, tips, and workbook hacks
TRUNC is easier to remember when you learn the small patterns around it: where it fits, what can break it, and how to combine it with neighboring functions.
Use these practical notes as a working checklist before putting the formula into a real report, model, dashboard, tracker, or reusable template.
Quick wins before you trust the result
- Start with the simplest TRUNC formula that answers the question, then add conditions or error handling only when needed.
- Keep input ranges consistent in size, shape, and meaning.
- Test the formula on one row or one small sample before filling it down a large workbook.
- Add a note beside important formulas explaining what business question they answer.
- Pair the formula with related checks so mistakes are easier to spot.
| Trick or hack | Formula pattern | Best use | Watch out |
|---|---|---|---|
| Build the formula in layers | TRUNC(number, [num_digits]) | When the full formula feels hard to read or debug. | Confirm each argument or nested function before combining everything. |
| Use structured references | =TRUNC(Table1[Column]) | Excel Tables make formulas easier to read and expand automatically. | Rename table columns carefully so formulas remain clear. |
| Protect against bad input | =IFERROR(TRUNC(...),"Check input") | Dashboards and shared templates where users need a readable message. | Do not hide errors until you understand why they happen. |
| Document the expected result | Add a note or nearby label | Reusable workbooks, finance models, templates, and handoff files. | A clever formula without context becomes expensive to maintain. |
| Mistake | What it looks like | Fix |
|---|---|---|
| Using a wider range than intended | The result changes unexpectedly after new rows or helper columns are added. | Use Excel Tables or named ranges to make the intended input explicit. |
| Mixing text, numbers, dates, and blanks | The answer technically works but does not match the business meaning. | Clean and validate the source column before applying the function. |
| Copying a formula with moving references | The first row works; later rows drift into the wrong range. | Use absolute references, structured references, or named ranges where needed. |
| Scenario | Use | Avoid |
|---|---|---|
| You need a quick answer from clean data | TRUNC with the smallest clear range | Overbuilding the formula with unnecessary wrappers |
| The result will appear in a dashboard | Add checks, labels, and readable fallbacks | Leaving raw errors or unexplained blanks for viewers |
| The workbook will grow over time | Excel Tables, named ranges, or structured references | Hard-coded ranges that miss new rows |
| The data comes from another system | Clean inputs before summarizing or transforming | Assuming pasted data has correct types and spacing |
Practice drills
- Write TRUNC once with direct cell references and once with an Excel Table reference.
- Break the formula on purpose, then use the error message to identify which argument failed.
- Create a small before/after example that explains the formula to another learner.
