What it means
Every lender is fundamentally a buyer and reseller of money. It gathers funds from depositors and wholesale markets at one price, puts them to work at a higher one, and keeps the difference after losses and running costs.
Cost of funds is simply the buying price in that arrangement. The figure is always a weighted average rather than a single rate.
A bank might pay almost nothing on current accounts, more on term deposits and considerably more on wholesale borrowing, so the blend depends entirely on how much money sits in each bucket. A shift in that mix changes the cost of funds even when no individual rate has moved.
It matters because it sets a hard floor under pricing. A lender whose funds cost 2.25% cannot profitably write a loan at 3.00% once expected credit losses, the cost of holding capital and operating expenses are all accounted for.
Every product price in a bank is built upward from this number. Cost of funds moves with central bank policy and with competition for deposits, and the two parts respond at different speeds.
When base rates rise, wholesale borrowing reprices almost immediately while deposit rates lag, which is why lending margins often widen briefly and then narrow as depositors demand better terms. For non-financial companies the same concept appears as the cost of debt inside the weighted average cost of capital.
The practical difference is that a manufacturer borrows to buy machines and stock, while a bank borrows to buy loans, but in both cases the borrowing rate sets the minimum acceptable return on whatever the money is spent on.
In practice
Real-world examples
Example 1
A credit union with almost all its funding in member savings accounts holds a cost of funds near 1.10%, well below competitors that rely on wholesale markets. That advantage lets it price mortgages roughly half a percentage point cheaper while earning the same spread.
Example 2
A specialist lender funded entirely by wholesale borrowing sees its cost of funds jump from 3.20% to 5.10% after a rate rise. Because its existing loan book is on fixed rates, the spread compresses immediately and the business has to reprice new lending or accept much thinner margins.
Example 3
A manufacturer refinances $12,000,000 of borrowing from 7.00% to 5.20% and cuts annual interest expense by $216,000. The finance director uses the lower cost of debt to justify a capital project that had previously fallen just below the required return.
Think of it
Think of the cost of funds like buying ingredients for a bakery. If you buy flour and sugar at a high wholesale price, you must charge more for your cakes to make a profit.
Formula
Calculation
Cost of funds = total interest expense / average interest-bearing liabilities x 100.
A regional bank is funded by two sources over the year.
Retail deposits average $300,000,000 at an average rate of 1.50%.
Wholesale borrowing averages $100,000,000 at an average rate of 4.50%.
Interest paid on deposits = $300,000,000 x 1.50% = $4,500,000.
Interest paid on wholesale borrowing = $100,000,000 x 4.50% = $4,500,000.
Total interest expense = $4,500,000 + $4,500,000 = $9,000,000.
Average interest-bearing liabilities = $300,000,000 + $100,000,000 = $400,000,000.
Cost of funds = $9,000,000 / $400,000,000 x 100 = 2.25%.
If the bank's earning assets yield 5.75%, the net interest spread = 5.75% - 2.25% = 3.50%. Notice that the smaller wholesale block contributes exactly half the interest bill despite being a quarter of the funding, which is why growing cheap retail deposits is such a persistent priority for lenders.Case study
Seen in the real world
The following is an illustrative and fictional scenario. Thornhaven Building Society had funded its lending almost entirely from wholesale markets because raising retail deposits was slow and required branch investment. Its cost of funds sat at 4.10% while a comparable local competitor operated at 2.30%.
The board initially treated the difference as a pricing problem and tried to compete on loan rates anyway, which produced volume but almost no margin. A review made the arithmetic uncomfortably clear: on a $700,000,000 book, the 1.80 percentage point gap in funding cost was worth $12,600,000 a year before a single loan decision was made.
Thornhaven changed strategy over three years, launching a savings product priced attractively but below wholesale rates and investing in the systems to service it. As the retail share of funding rose towards half the balance sheet, the blended cost of funds fell to 3.15%. The illustrative point is that competitiveness in lending frequently depends far less on lending skill than on where a business sources its money.
Watch out
Common mistakes
- Quoting the headline rate on one funding source as if it were the whole cost of funds, when the real figure is a weighted blend across every interest-bearing liability.
- Assuming a low cost of funds automatically means high profitability, when credit losses, capital requirements and operating costs can easily consume the entire spread.
- Comparing cost of funds between institutions without checking whether both include the fees, hedging costs and deposit insurance charges that attach to raising the money.
Questions
People also ask
How is cost of funds different from net interest margin?
Cost of funds is only the price paid for money, while net interest margin measures the difference between what the assets earn and what the funding costs, expressed against earning assets.
Why do banks compete so hard for current account balances?
Because those balances typically pay little or no interest, and every dollar of them pulls the blended cost of funds down and widens the spread on all lending.
Does cost of funds apply to companies outside banking?
Yes, though it is usually called the cost of debt and feeds into the weighted average cost of capital that sets the hurdle rate for investment decisions.