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ROUNDDOWN Function in Excel - Round Down Numbers & Floor Values

Round numbers down toward zero with this Excel function....

Quick Start

Syntax

=ROUNDDOWN(number, num_digits)

Parameters

number - Required. The numeric value to round down toward zero.

num_digits - Required. Number of decimal places. Positive = decimals (2 = 12.34), Zero = whole (0 = 12), Negative = left of decimal (-1 = 10).

Simplest Example

ABC
1ValuePrecisionResult
23.90
31234.5672
4-5.80
5
=ROUNDDOWN(A2, B2)
3

Quick Reference

Round to Whole Number
=ROUNDDOWN(3.9, 0)

Removes all decimals, rounds toward zero

3.9 → 3, -5.8 → -5

Round to 2 Decimal Places
=ROUNDDOWN(1234.567, 2)

Keeps 2 decimals, truncates rest

1234.567 → 1234.56

Round to Nearest 10
=ROUNDDOWN(847, -1)

Negative precision rounds left of decimal

847 → 840, 153 → 150

Floor Price Below Dollar
=ROUNDDOWN(24.99, 0) - 0.01

Create $.99 pricing psychology

24.99 → $23.99

Real-World Examples

Conservative Budget Estimates

Use this Excel function to create conservative budget forecasts that never exceed available funds. Financial planners and CFOs use this formula to ensure budget estimates stay below targets, providing a safety margin for unexpected costs. This rounding approach is essential for grant applications, project proposals, and departmental budgets where exceeding limits could cause compliance issues or funding rejection. Round down 90% of forecast to whole dollars for a built-in buffer that protects against cost overruns while maintaining realistic planning figures.

ABC
1CategoryForecastConservative
2Marketing$52,780
3Safe Estimate:
=ROUNDDOWN(B2*0.9, 0)
$47,502
Pro Tip: Multiply by 0.9 then ROUNDDOWN for 10% safety margin below projections.
Pattern: =ROUNDDOWN(Forecast*0.9, 0) for conservative budgets
Inventory Packs - No Partials

Calculate complete packs only with this Excel function, eliminating partial pack quantities. Warehouse managers and procurement teams use this formula to determine how many full cases or packs can be created from available inventory, preventing shipment of incomplete units. This technique is critical for wholesale distribution, bulk packaging operations, and manufacturing scenarios where partial packs cannot be sold or shipped. Round down total quantity divided by pack size to get complete packs, ensuring accurate order fulfillment and inventory planning without remainder units.

ABC
1ItemQuantityPack SizeFull Packs
2Widgets15712
3Complete:
=ROUNDDOWN(B2/C2, 0)
13
Pattern: =ROUNDDOWN(quantity/pack_size, 0) for complete units only

Common Mistakes to Avoid

=ROUND(3.9, 0)Using ROUND instead of ROUNDDOWN

❌ The Problem:

  • ROUND rounds 3.9 up to 4 (standard rounding)
  • ROUNDDOWN always goes toward zero (3.9 → 3)
  • Creates values higher than conservative limits
  • Defeats purpose of floor-based calculations

✅ Solution:

=ROUNDDOWN(3.9, 0)

Use ROUNDDOWN when you need values to never exceed a threshold. This function always truncates toward zero, making it perfect for conservative estimates, compliance calculations, and scenarios where rounding up could violate limits or budgets. ROUND uses standard rounding rules (0.5 and above rounds up), while ROUNDDOWN provides predictable floor behavior.

=ROUNDDOWN(-5.8, 0) expecting -6Misunderstanding negative number behavior

❌ The Problem:

  • ROUNDDOWN(-5.8, 0) returns -5, not -6
  • Always rounds TOWARD zero, not DOWN in absolute terms
  • Confusing for those expecting floor behavior
  • Different from FLOOR function for negatives

✅ Solution:

=ROUNDDOWN(-5.8, 0) → -5

The function rounds toward zero for both positive and negative numbers. For -5.8, toward zero means -5 (less negative). If you need to always round down in absolute terms regardless of sign, use the <Link href="/formulas/floor">FLOOR</Link> function instead. This function is named for its behavior with positive numbers, but think "toward zero" for accurate mental model.

=ROUNDDOWN(A1/B1, 2) with division errorsNot handling division by zero

❌ The Problem:

  • Returns #DIV/0! error when B1 is zero
  • Breaks entire formula chain
  • Common in inventory or ratio calculations
  • No fallback for missing divisor

✅ Solution:

=IF(B1=0, 0, ROUNDDOWN(A1/B1, 2))

Wrap the function with error-checking logic when dividing. Use <Link href="/formulas/if">IF</Link> to test for zero divisor, or <Link href="/formulas/iferror">IFERROR</Link> to catch all errors: =IFERROR(ROUNDDOWN(A1/B1, 2), 0). This ensures your formula returns a sensible default instead of propagating errors through your calculations.

Frequently Asked Questions

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