What it means
Interest rates are often quoted annually even when balances change daily, so a daily factor translates the rate into a smaller calculation unit. This helps a lender, investor or treasury team calculate accrual over shorter periods.
Under a simple-interest convention, an annual decimal rate can be divided by the stated number of days in the year, and a 360-day basis and a 365-day basis produce different factors from the same annual rate. The contract or product method determines which basis is appropriate.
An effective annual rate already reflects compounding over a year, so its equivalent daily compounded rate is not generally obtained by merely dividing by 365. The difference can matter when comparing quoted products or reconciling accrued amounts.
TreasuryDirect's SLGS daily-rate guide displays a daily factor beside an annualised effective rate for demand-deposit securities. That is a specific public-security calculation context, and it illustrates why the displayed factor and its convention should be read together.
A decimal factor must also be distinguished from a percentage: a factor of 0.0001 corresponds to 0.01% for the day, and multiplying a balance by 0.01 instead would create an error of one hundred times. The applicable balance also matters, since a fixed face amount, purchase price and daily account balance can differ.
A yield based on market price is not automatically the contractual coupon rate used to compute a bond payment. If balances change, calculate each day's interest on the relevant balance rather than using the ending amount for the entire month, and check when the terms say funds become eligible to earn interest.
Interest accrual is different from cash distribution, because a daily calculation may build up an amount paid monthly or on another schedule. Receiving no payment today does not mean no interest accrued today.
Rounding can affect reconciliation, as providers may retain several decimal places in the factor and round only the final payment, whereas repeatedly rounding each daily amount can produce a different total from the official method. A variable rate can produce different factors on different days, so holding yesterday's factor constant through a rate change gives a misleading estimate, and the effective dates and calculation periods should be kept with the rates.
A daily yield quote does not include every investment risk, since bond prices can change, issuers can default and fees can reduce the amount earned. For a non-finance manager, identify the annual rate type, day-count basis and balance before calculating, then check accrual and payment timing.
In practice
Real-world examples.
Example
A deposit pays an illustrative 3.65% simple annual rate on a 365-day basis. Its daily factor is 0.0001, so a $10,000 eligible balance accrues $1 for one day.
Example
A loan uses a 360-day basis at the same annual nominal rate. Its daily factor differs from a 365-day calculation, so the borrower checks the contract before comparing daily interest.
Example
An account balance rises halfway through a month. The administrator separates the days before and after the deposit instead of applying the higher balance to every day.
Formula
Calculation
Simple daily factor = nominal annual decimal rate / contractual day-count denominator. Equivalent daily compounded factor = (1 + effective annual rate)^(1/N) - 1, where N is the number of compounding days assumed.
Worked example. At 3.65% simple annual interest and a 365-day basis, the factor is 0.0365 / 365 = 0.0001. Daily interest on $20,000 is $20,000 x 0.0001 = $2, before any fees or further adjustments.
Basis comparison. The same 3.65% rate on a 360-day basis gives 0.0365 / 360 = 0.000101389 (to nine decimal places), so daily interest on $20,000 is about $2.03. Over a 30-day month that is roughly $60.83 on a 360-day basis against $60.00 on a 365-day basis, which is why the contract basis must be confirmed before reconciling.Case study
Seen in the real world.
Fictional case: A treasury assistant estimates one month's interest on a short-term balance by dividing its annual rate by 365. The posted amount differs, so she checks whether the quote is an effective annual rate and whether the provider uses a different day-count convention. She also finds that part of the balance was deposited later in the month.
She rebuilds the calculation using dated balances and the product's factor, retaining precision until final rounding. The corrected estimate matches the method rather than treating the difference as an unexplained bank charge. The fictional lesson is that a small gap between estimate and statement usually has a traceable convention behind it.
Watch out
Common mistakes.
- Confusing a decimal factor with a percentage or with the cash earned each day.
- Dividing an effective annual rate by a day count without checking compounding.
- Using the wrong balance, rate dates or rounding procedure for an accrual period.
Questions
People also ask.
Is the daily factor always the annual rate divided by 365?
No. Day-count and compounding conventions can require another calculation.
Does a daily factor mean interest is paid daily?
No. Accrual and payment schedules are separate.
Can equal annual rate quotes produce different daily amounts?
Yes. Their conventions, balance definitions and rate types may differ.
From the founder's library
Take it further with the book.
Build your financial confidence beyond this definition. Shihan's full-length guide, Accounting Fundamentals, takes the same plain-English approach and turns it into a complete, practical playbook for non-finance managers, business owners and students - with chapter-end quiz answers and presentation slides included.
25% off with code MMHQ25, applied at checkout. Priced in USD - checkout may show the equivalent in your local currency.
View the book and save 25%