Math & Trig

ROUNDDOWN Function in Excel

Rounds a number down, toward zero.

Syntax

  • =ROUNDDOWN(number, num_digits)

Arguments

  • number (required): The number to round down
  • num_digits (required): Number of decimal places

Examples

  • =ROUNDDOWN(3.9, 0) - Round down to integer - Result: 3
  • =ROUNDDOWN(76.9, -1) - Round down to tens - Result: 70

ROUNDDOWN in reporting workflows

  • Use absolute references when copying formulas across rows.
  • For conditional totals see [SUMIF](/functions/sumif/) and [SUMIFS](/functions/sumifs/).
  • Filtered lists may need [SUBTOTAL](/functions/subtotal/) instead of SUM on visible cells only.

Common errors

  • Always rounds toward zero

Use cases

  • Conservative estimates
  • Floor calculations
  • Truncation

Frequently asked questions

  • What's the difference between ROUNDDOWN and TRUNC? They're nearly identical! Both round toward zero. The only difference is TRUNC's second argument is optional (defaults to 0), while ROUNDDOWN requires it. =ROUNDDOWN(3.7, 0) = =TRUNC(3.7) = 3.
  • When should I use ROUNDDOWN vs FLOOR? ROUNDDOWN rounds to decimal places (0, 1, 2...). FLOOR rounds to multiples (0.05, 5, 10...). Use ROUNDDOWN for precision control, FLOOR for rounding to specific increments like pricing tiers.

Editorial review

  • Reviewed by Excel.Directory Editorial Team. Updated May 2026.

When to use ROUNDDOWN

  • Conservative estimates — common Math & Trig scenario for ROUNDDOWN.
  • Floor calculations — common Math & Trig scenario for ROUNDDOWN.
  • Truncation — common Math & Trig scenario for ROUNDDOWN.

ROUNDDOWN in the Math & Trig category

  • Browse all Math & Trig functions at /categories/math-trig/ for related formulas.
  • ROUNDDOWN syntax: =ROUNDDOWN(number, num_digits)
  • number (required): The number to round down
  • num_digits (required): Number of decimal places
  • Confirm ROUNDDOWN arguments match the syntax shown above before filling down.
  • Lock table and range references with $ when copying formulas across rows or sheets.

Formula checklist before you copy down

  • Confirm ROUNDDOWN arguments match the syntax shown above before filling down.
  • Lock table and range references with $ when copying formulas across rows or sheets.
  • If results look wrong, check for text stored as numbers and invisible spaces with TRIM.
  • Spot-check three known input rows manually against expected output.

Related Excel functions

  • ROUNDUP (/functions/roundup/): Rounds a number up, away from zero.
  • ROUND (/functions/round/): Rounds a number to a specified number of digits.
  • FLOOR (/functions/floor/): Rounds a number down to the nearest multiple of significance.
  • TRUNC (/functions/trunc/): Truncates a number to an integer by removing the decimal part.

Errors to watch for

  • Always rounds toward zero — review causes on linked error pages in the directory.

Copy-paste audit workflow

  • Enter ROUNDDOWN on three test rows with known expected output documented on a QA tab.
  • Fill down only after absolute references are locked on lookup tables and rate tables.
  • Compare against manual calculation or a calculator for financial and statistical functions.
  • Search this directory for comparison guides when choosing between similar functions in the same category.

ROUNDDOWN worked examples to copy

  • =ROUNDDOWN(3.9, 0) — Round down to integer. Expected result: 3.
  • =ROUNDDOWN(76.9, -1) — Round down to tens. Expected result: 70.

ROUNDDOWN reference summary for crawlers and offline review

  • ROUNDDOWN belongs to the Math & Trig category in Excel. Rounds a number down, toward zero.
  • Full syntax: =ROUNDDOWN(number, num_digits). Open /functions/rounddown/ for parameters, FAQs, and related pages.
  • Common mistakes: Always rounds toward zero
  • Pair this function with comparison guides when another Excel formula might fit the same task better.
  • Review fix-excel-formula-errors when unexpected errors appear after upgrading Excel or sharing across locales.