COUPDAYS in Collabora Office: Find the Coupon-Period Day-Count Denominator
Use Collabora COUPDAYS to obtain a coupon-period day measure, understand the documented 182.5-day result, and avoid confusing it with calendar days.
Verification status: See the evidence and test scope described in this guide. How formula examples are checked
Quick answer: =COUPDAYS(DATE(2001;1;25);DATE(2001;11;15);2;3) has documented result 182.5. Under this semiannual actual/365 example, the period measure is 365/2, not the actual number of calendar days between its coupon dates.
Syntax and selected basis
=COUPDAYS(Settlement; Maturity; Frequency [; Basis])
Settlement identifies the current coupon period. Maturity anchors the security’s ending date. Frequency gives payments per year and is required. Basis is optional and defaults to zero.
| Basis | Documented day-count convention |
|---|---|
| 0 or omitted | US NASD, twelve 30-day months |
| 1 | Actual days in months and actual days in the year |
| 2 | Actual days in months, 360-day year |
| 3 | Actual days in months, 365-day year |
| 4 | European method, twelve 30-day months |
Use explicit date values, preferably DATE formulas, rather than ambiguous date-looking text. Frequency is a number of payments per year, not a number of months: 1, 2, and 4 mean annual, semiannual, and quarterly payments. Monthly frequency 12 is outside the stated contract.
The result is a measure of the full coupon period containing settlement, not elapsed days since the previous coupon, remaining days until the next coupon, or the count of coupons left. The fractional documented result is intentional; it is not evidence that a date contains half a calendar day.
Example: reproduce and audit the documented period
Put =DATE(2001;1;25) in A2, =DATE(2001;11;15) in B2, 2 in C2, and 3 in D2. In E2 enter =COUPDAYS(A2;B2;C2;D2).
The source result is 182.5. An independent arithmetic control =365/C2 also gives 182.5. The regular surrounding coupon dates are November 15, 2000 and May 15, 2001, whose actual date difference is 181 days.
These values describe different things. Rounding E2 to 183 or changing the formula to return 181 would erase the documented convention-based measure. Keep enough decimal places to show the half-day result.
Example: compare regular-period conventions
For the same settlement, maturity, and semiannual frequency, the independently modeled period measures are:
| Basis | Independent expectation | Reason |
|---|---|---|
| 0 | 180 | 360/2 under 30-day months |
| 1 | 181 | Actual surrounding coupon dates |
| 2 | 180 | 360/2 convention |
| 3 | 182.5 | 365/2, directly documented |
| 4 | 180 | 360/2 under European 30-day months |
Only the basis-three 182.5 result is the explicit numeric control in the function’s own section. The other entries are transparent independent applications of the listed conventions to this regular schedule; they are not a native cross-basis test.
Advanced example: isolate the numerator from the denominator
For the documented period, the related COUPDAYBS and COUPDAYSNC sections give elapsed and remaining counts 71 and 110. They add to 181 actual days. COUPDAYS gives 182.5 under basis three.
If an accrual model uses elapsed days divided by the COUPDAYS denominator, its independent fraction is =71/182.5, approximately 0.389041096. Using actual elapsed days divided by the actual full interval gives =71/181, approximately 0.392265193. Those are distinct conventions, not interchangeable rounding approximations.
Retain the basis and each component alongside any final amount so a reviewer can see which model was applied. This example explains arithmetic; it does not choose contractual or investment terms.
Advanced application: compare payment frequencies
Under the same fixed-365 denominator idea, annual, semiannual, and quarterly periods correspond independently to 365, 182.5, and 91.25. Store frequencies 1, 2, 4 in separate rows and calculate =365/frequency as a visible convention check.
The actual calendar lengths of regular coupon periods vary by months and leap years. Do not interpret a 91.25 convention denominator as a claim that every quarter contains exactly that many elapsed days.
DATE constructs actual boundary dates; ROUND controls a later display or reporting amount. Date arithmetic and period conventions should remain separate columns.
Errors and limitations
The dedicated section provides the convention list and the exact 182.5 control, but not a complete native error table or every irregular schedule and month-end rule. Use valid dates with settlement before maturity and a permitted frequency. Fractional frequencies and monthly frequency 12 are outside the stated contract.
There are no issue-date or first/last odd-coupon arguments. Validate an unusual security’s schedule rather than treating this regular-period helper as a complete bond model. Native precision, coercion, and boundary behavior are not certified by the independent calculations here.
Availability and verification
The exact function is documented in Collabora Office 26.04 desktop help, retrieved and reviewed on October 17, 2026. This establishes a documentation scope, not the first release that introduced the function or the last version in which it works; those versions and any retirement date remain unestablished. Collabora Online and mobile support are not inferred from desktop help, nor is behavior in another spreadsheet product.
The examples are documentation-based expectations with independent calculations. They have not been executed in Collabora Office. No application screenshot or native error/coercion certification is implied. Formulas use English function names and semicolon argument separators.
References
- Collabora Office 26.04: COUPDAYS (checked October 17, 2026).
- Editorial testing standards.