What a call loan is
A call loan is an open-ended credit facility with no fixed maturity date. The lender can call the loan in at any time with short notice, and the borrower can generally repay all or part of the principal whenever funds allow. In financial markets, call loans are frequently used by broker-dealers to finance margin accounts against pledged securities. Simple interest is charged on the balance outstanding, and unpaid interest does not compound into the principal.
Worked example: £15,000 with one part-payment and a rate change
£15,000 is lent on 2 March 2026 at 6.5% a year. £2,000 is paid on 1 May, the rate rises to 7.5% on 1 July and the loan is settled on 2 September. Over 184 days, interest charged comes to £473.59. The £2,000 first clears the interest built up to 1 May and the rest reduces the balance, leaving £13,160.27 owed with £313.32 of interest unpaid, so £13,473.59 clears the loan on 2 September.
Published examples reproduced
Gatehouse Chambers' simple interest calculator counts both the first and the last day. For £10,000 at 8% a year from 15 January to 14 May 2026 it gives 120 days and £263.01, and with the option to count both days this calculator gives 120 days and £263.01. A monthly rate is multiplied by 12 first: 0.5% a month on £10,000 from 1 January to 31 March 2026 is 90 days and £147.95.
Days in the year and day counting conventions
Interest for a day is the yearly rate divided by the days in the year. Gatehouse uses the real length of the year, so 8% on £10,000 for the whole of 2024 is £800.00 over 366 days. On a fixed 365-day basis the same 366 days costs £802.19. This calculator offers 365 days (the default), 360 days and actual days in each year, and either counting the days between the dates or counting both the first and the last day. Check your loan terms for which applies.
Part-payments, advances and rate changes
A part-payment pays the interest built up so far first and then reduces the balance. If it is smaller than the interest, the unpaid interest carries forward and the balance does not fall: a £50 payment on 1 April against £15,000.00 lent leaves the full balance and £441.51 of interest unpaid at the end. An advance adds to the balance from its date, and a rate change applies from its date. Interest for each stretch is rounded to the penny, as in a repayment schedule.
For demand loans with similar terms, see the demand loan calculator.
For fixed-term borrowing, see the simple interest loan calculator.
What this does not cover
Interest here is simple: unpaid interest is not compounded. Whether a particular loan is regulated credit, the interest a court might award, and statutory interest on late-paid business invoices are different questions with different rules, and are not calculated here. Take advice on a dispute.
Inputs for the call loan calculator
Amount borrowed and interest rate
The balance on the start date and the simple rate. Choose whether the rate is per year, month, week or day.
Days in the year and counting days
365, 360 or actual days; days between the dates, or counting the first and last day as well.
Loan start date and settlement date
Interest runs from the day after the start date up to the settlement date.
Part-payments
How many payments you make before settling, each with a date and an amount.
Further advances
Extra money lent after the start, each with a date and an amount.
Rate changes
Dates when the rate changes, each with the new rate for the same period as the rate above.
CALCULATOR QUESTIONS
Call loan calculator questions
How is interest on a call loan calculated?
Simple interest on the balance outstanding: balance times yearly rate times days, divided by the days in the year, worked out for each stretch between events and rounded to the penny.
What is the difference between a call loan and a term loan?
A term loan has a fixed repayment schedule and maturity date. A call loan has no fixed term and can be recalled by the lender at any time.
What is a broker call loan?
A short-term collateralized loan from a commercial bank to a brokerage firm, used by the broker to finance margin loans for clients.
What happens if a part-payment is less than accrued interest?
The payment pays down a portion of the interest. The remaining unpaid interest carries forward to the next period, while the loan principal remains unchanged.
Can interest rates on call loans change?
Yes. Call rates fluctuate frequently with prevailing central bank policy rates, and lenders can adjust the rate on short notice.