DISC Function in Excel: Discount Rate of a Security

DISC Function in Excel: Discount Rate of a Security featured illustration

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⏱ 2 min readUpdated 28 September 2026

FinancialLevel: ExpertAvailable in: Excel 2007+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. DISC in practice
  5. Where you will use it
  6. Worked example
  7. Mistakes people make
  8. Related functions
  9. Continue learning

DISC works out the discount rate when you know the purchase price and redemption value — commercial paper, bill discounting.

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Syntax

=DISC(settlement, maturity, pr, redemption, [basis])
Argument What it means
basis 0 = US 30/360, 2 = actual/360, 3 = actual/365.

Examples

Example 1

=DISC(DATE(2021,4,1), DATE(2021,6,30), 98.5, 100, 3)

Annual discount rate on a 90-day bill bought at 98.5.

DISC in practice

Where you will use it

  • Discount rate of a T-bill or commercial paper
  • Money-market yields
  • Treasury desks

Worked example

SettlementMaturityPriceFormulaResult
01-Oct-202630-Dec-202698.2=TEXT(DISC(A2,B2,C2,100,2),"0.00%")7.20%
01-Oct-202630-Mar-202796.4=TEXT(DISC(A3,B3,C3,100,2),"0.00%")7.20%
01-Oct-202630-Sep-202793.1=TEXT(DISC(A4,B4,C4,100,2),"0.00%")6.82%

Results calculated in Excel.

Mistakes people make

MistakeWhat to do instead
Price per 100Enter price per 100 of face value
Basis2 = actual/360, 3 = actual/365

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