TBILLPRICE Function (LibreOffice Calc)

TBILLPRICE estimates the purchase price per 100 currency units of face value for a discounted, non-coupon Treasury bill. If a bill redeems at 100 and sells at 98.45, the implied discount from par is 1.55 per 100. The annual discount quote is a different measure from the investor’s annualized yield. TBILLPRICE consumes the quoted discount rate and dates; its paired function TBILLYIELD consumes the resulting purchase price.

Because this is a per-100 quotation, the output 98.45 means a face value of 10,000 would imply 98.45/100*10000 = 9,845 purchase cost before fees, assuming the stated bill and quote apply. The function does not include transaction costs, taxes, brokerage commissions, currency conversion or settlement conventions imposed by your institution.

TBILLPRICE(Settlement; Maturity; Discount)

There are exactly three required arguments, with no documented optional default or Basis argument. A fourth argument is a syntax error in the tested version. The ODF 1.4 OpenFormula specification requires the discount to be positive and maturity to be less than one year beyond settlement. Do not rely on the tested release to enforce every constraint (see limits below).

The Help example assumes a purchase on 1999-03-31, maturity on 1999-06-01 and annual discount of 9%.

=TBILLPRICE(DATE(1999;3;31);DATE(1999;6;1);9%)

Native Calc 25.2.3.2 result: 98.45. This also reproduces LibreOffice 26.8 Help’s result using ISO date text: =TBILLPRICE("1999-03-31";"1999-06-01";0.09). The two dates have 62 actual days between them. With the conventional Actual/360 bank-discount arithmetic,

Price = 100 × (1 − 0.09 × 62/360) = 98.45

This agreement is real for the illustrated dates, not a guarantee that the tested Calc version follows Actual/360 for all dates. All 62-day example assertions were directly evaluated, not invented.

Do it with worksheet cells

Use real spreadsheet dates rather than unvalidated imported strings. If D2 and F2 differ on a different bill, determine the date convention and compare your platform to the bill documentation instead of forcing a presumed answer.

The comparison below separates observed native Calc output from the independently calculated Actual/360 price. The independent price uses (Maturity−Settlement) as the elapsed calendar days and 100*(1−Discount*Days/360). Numerical results were checked by Decimal arithmetic and a second native DAYS diagnostic.

What the source check establishes: In the LibreOffice 25.2.3.2 implementation, getTbillprice first advances maturity by one calendar day, then uses the US/NASD 30/360 year-fraction helper, mode 0. It prices the bill as 100*(1-Discount*YearFraction). Thus January 1–April 1 uses 91 convention days after the maturity adjustment, while February 28–March 1, 2024 uses four convention days. This release-specific mapping independently reproduces all 36 saved TBILLPRICE cases, including six errors. It is not an unconditional Actual/360 rule or a claim about untested versions.

How to independently audit another date pair

For a bill with settlement in A2, maturity B2 and discount rate C2:

=TBILLPRICE(A2;B2;C2)
=100*(1-C2*DAYS(B2;A2)/360)
=TBILLPRICE(A2;B2;C2)-100*(1-C2*DAYS(B2;A2)/360)

The first line is the platform function; the second is an explicit independent Actual/360 calculation; the third is a discrepancy check (zero only if they agree). This direct check is useful when migrating financial sheets or handling month-end settlements. It is not a certified alternative for a broker’s actual financial convention.

Given A2/B2/C2 as in the official 1999 example, enter G2 = 10,000 as the face value. Then:

=G2*TBILLPRICE(A2;B2;C2)/100

Independent multiplication gives 9,845 currency units for the purchase value, before fees; this scaled worksheet formula was not separately native-tested. Face-value profit upon redemption would be =G2-G2*TBILLPRICE(A2;B2;C2)/100, or 155. To compare the investor’s annualized yield rather than the bank discount, use:

=TBILLYIELD(A2;B2;TBILLPRICE(A2;B2;C2))

The historical price and yield calls for this date pair agree with about 0.0914169629, or 9.14169629%; the displayed nested cell-reference layout is reproducible guidance rather than an additional recorded native assertion. This is correctly different from 9%, because an investment yield annualizes profit against the purchase cost, not the $100 redemption value. Never treat TBILLYIELD as the inverse of the discount quote.

The one-year observations are particularly important: ODF requires a maturity less than one year beyond settlement, yet Calc 25.2.3.2 accepted dates more than a calendar year out in one test and rejected a 363-day interval in another. The checked source explains this: after advancing maturity, it rejects an integral year fraction, rather than applying a simple less-than-one-year ceiling. A 363-day calendar interval becomes exactly one convention year and is rejected, while some longer nonintegral fractions pass. This finding applies to the checked 25.2.3.2 implementation, not all releases.

Safer model-side input checks

A reviewable guard formula is:

=IF(NOT(AND(ISNUMBER(A2);ISNUMBER(B2);ISNUMBER(C2)));"Check bill inputs";IF(AND(A2<B2;B2<EDATE(A2;12);C2>0);TBILLPRICE(A2;B2;C2);"Check bill inputs"))

This enforces a conservative Maturity < Settlement+12 months policy matching the strict wording of ODF for a one-year bill; some market conventions accept a bill that matures exactly one year after settlement, so adapt any real trading rule to your counterparty’s contract rather than assuming this screen is authoritative. This guard is suggested input validation, not an additional native assertion. Use the guard as a conservative input screen; it does not change the function’s internal date convention.

Troubleshooting before sharing a spreadsheet

Check the locale’s argument separator and decimal setting, verify that the date cells are real numbers formatted as dates, and compare =DAYS(B2;A2) with a calendar. A price formatted with two decimals can hide small discrepancies that become material on large face values. Keep full precision for intermediate arithmetic, show the exact settlement/maturity, and keep the 25.2.3.2 behavior warning when the file is opened in a newer release.

Use DATE(year;month;day) or genuine spreadsheet date cells. DATE avoids the ambiguity of 04/01/2026, which means different dates in different locales. ISO-8601 quoted strings were accepted in the reproduced official 1999 example, but text date parsing is locale-sensitive and should not be the foundation of a reusable model. The examples on this page use Calc’s common English-function-name setting, a . decimal mark and semicolon argument separators. In some locales or customized settings, function names, decimal marks and separators appear differently. The function has no Basis argument, so do not append a fourth day-count parameter.

For reproducibility with cell references, place A2 = 2026-01-01 and B2 = 2026-04-01 as genuine dates (or compute them with =DATE(2026;1;1) and =DATE(2026;4;1)). Check =DAYS(B2;A2) = 90 in the native tested version. Date serial systems and importing a CSV can affect older workbook values; verify any imported dates.

Treasury-bill quotes often use a bank-discount convention, whose discount rate is quoted relative to face value, not investment cost. A money-market investment yield uses the purchase price as its denominator. That is why a discount of 9% and the yield on the resulting $98.45 price are not the same percentage.

There is also a separate, material date-count portability risk. The independent Actual/360 reference formulas in this article intentionally calculate elapsed calendar days with DAYS; they are not claimed to be the exact formula engine implementation on every LibreOffice build. A 72-case native Calc 25.2.3.2 comparison found 29 matches and 43 differences between the tested TBILLPRICE/TBILLYIELD outputs and independent Actual/360 benchmarks (36 cases per function). Errors near month ends and year boundaries can be financially significant. The observed differences are retained rather than edited out. For settlement or valuation decisions, compare against the bill’s official quote and the precise convention used by your institution.

The current LibreOffice 26.8 Help gives these functions’ syntax and examples but does not document every observed Calc 25.2.3.2 date-count edge case. Version 26.8 was documentation-checked, not executed. The ODF 1.4 OpenFormula specification defines the names, argument types and one-year/positive-input constraints, but these checks cannot prove that every Calc release follows the same constraints. Do not assume identical outputs merely because another spreadsheet advertises a function with the same name.

Historical numerical records, saved formulas and ODS outputs were compared directly. The 72 actual-day benchmark comparisons and 30 additional diagnostics are corroborated by the saved workbook. An independent source-based calculation now explains all 72 numerical outputs and errors for the checked release. The original 25 attempts to equate investment yield with discount quote used an invalid financial assumption and are not scored as function failures. The actual-day benchmark remains useful as a separate convention check, not a description of this implementation.

Migration compatibility: what was—and was not—verified

Related functions and date-count tools:

• TBILLEQ — bond-equivalent yield (LibreOffice Help)
• PRICEDISC — discount-security pricing with explicit Basis
• YIELDDISC — discount-security yield with explicit Basis
• DAYS — actual elapsed dates
• DAYS360 — 30/360 date calculation
• YEARFRAC — fractional years

Implementation evidence: Financial functions at tag libreoffice-25.2.3.2 and date helpers at the same tag, retrieved 13 October 2026. The source interpretation explains the recorded version; the executable was not rerun.