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DAYS360 Function (LibreOffice Calc)

Date & Time Intermediate LibreOffice Calc Introduction not established

The DAYS360 function calculates the number of days between two dates based on a 360-day year. It is commonly used in financial calculations, interest accrual, and accounting schedules.

Verification status: Consult the documentation, examples and any stated test scope below. How formula examples are checked

Availability and version history

  • Introduced: Documented by LibreOffice 26.8.1.1; original introduction not established.
  • Availability: Supported in LibreOffice 26.8.1.1, verified against its function registry. This identifies a supported release, not a final working version.
  • Scope: Desktop Calc, using the English function name. Availability in other spreadsheet applications is separate.
  • Checked: 2026-10-14 — function reference; versioned support. Documentation/source check; not a new native test. Existing example-specific test claims below retain their stated scope.
The **DAYS360** function calculates the number of days between two dates using a standardized 360‑day year (12 months × 30 days). This method is widely used in financial calculations such as interest accrual, loan amortization, and accounting schedules. DAYS360 supports both **US (NASD)** and **European** conventions.

What the DAYS360 Function Does

  • Calculates day differences using a 360‑day year
  • Supports US (NASD) and European methods
  • Normalizes end‑of‑month behavior
  • Ideal for financial and accounting workflows

It is designed to be consistent, predictable, and aligned with industry standards.

Syntax

DAYS360(start_date; end_date; [method])

Arguments

  • start_date:
    The beginning date.

  • end_date:
    The ending date.

  • method (optional):
    FALSE or omitted → US (NASD) method
    TRUE → European method

Method Comparison

Method Behavior
US (NASD) Adjusts end‑of‑month dates with special rules
European Always treats months as 30 days, no special cases

Basic Examples

US method (default)

=DAYS360("2024-01-01"; "2024-02-01")

Returns 30.

European method

=DAYS360("2024-01-01"; "2024-02-01"; TRUE)

Returns 30.

Using cell references

=DAYS360(A1; B1)

Negative result (if reversed)

=DAYS360("2024-02-01"; "2024-01-01")

Returns -30.

Advanced Examples

Interest accrual for a 30/360 bond

=Principal * Rate * DAYS360(Start; End) / 360

Days between month‑end dates (US method)

=DAYS360("2024-01-31"; "2024-02-28")

Returns 28 (US rules adjust Feb 28 → Feb 30).

Days between month‑end dates (European method)

=DAYS360("2024-01-31"; "2024-02-28"; TRUE)

Returns 30.

Days between two dynamic dates

=DAYS360(TODAY(); EOMONTH(TODAY(); 1))

Days in a financial quarter

=DAYS360(A1; EDATE(A1; 3))

Days between Excel serial dates imported as text

=DAYS360(DATE(1899;12;30)+VALUE(A1); DATE(1899;12;30)+VALUE(B1))

Days between ISO date strings

=DAYS360(DATEVALUE("2024-03-15"); DATEVALUE("2024-01-01"))

US vs European Method Details

US (NASD) Rules

  • If start_date is the 31st → treated as 30th
  • If end_date is the 31st and start_date < 30 → end_date becomes 1st of next month
  • If both dates are the 31st → both become 30th

European Rules

  • Both dates’ day components are capped at 30
  • No special end‑of‑month adjustments

Edge Cases and Behavior Details

DAYS360 returns a number, not a date

Accepts:

  • Real dates
  • Serial numbers
  • DATEVALUE outputs

Invalid text → Err:502

DAYS360 allows negative results

Time components are ignored

Leap years do not matter

360‑day calendar is artificial.

Common Errors and Fixes

Err:502 — Invalid argument

Cause:

  • Text not recognized as a date
  • Non-numeric values

Fix:

  • Wrap with DATEVALUE
  • Clean text with TRIM or SUBSTITUTE

Unexpected results at month‑end

Cause:

  • US method’s special rules

Fix:

  • Use European method (TRUE) for predictable behavior

Negative result unexpected

Fix:

  • Reverse argument order

Best Practices

  • Use US method for US‑style financial instruments
  • Use European method for international accounting
  • Normalize text dates with DATEVALUE
  • Use DAYS360 for interest, amortization, and accrual schedules
  • Use DAYS for actual day counts
  • Use YEARFRAC for fractional‑year calculations
DAYS360 is your financial‑calendar engine — perfect for interest accrual, amortization schedules, and any workflow requiring a standardized 360‑day year.
  • Use DAYS for actual day counts
  • Use DATEDIF for mixed-unit intervals
  • Use YEARFRAC for fractional-year differences
  • Use EDATE and EOMONTH for month offsets
  • Use DATE for constructing comparison dates

By mastering DAYS360 and its companion functions, you can build precise, consistent, and finance‑ready date workflows in LibreOffice Calc.