What a Loan Really Costs: Rate, APR and the Total You Repay

One loan has a lower rate, another a smaller monthly payment, and neither number tells you which is cheaper. Compare offers over the same term by the total you will repay against the cash you actually receive, and by the annual cost the law makes lenders show — APR in the US and the UK. Then check what that figure leaves out: fees, insurance and the length of the loan change the price more than the headline rate suggests.

What is happening

Personal loans are usually repaid in equal monthly payments; each covers the month's interest first, so interest is front-loaded. The payment is A = P·r / (1 − (1 + r)^−n), where P is the loan, r the annual rate divided by twelve and n the number of months. For 100,000 units at 15% a year (a scenario, not a market rate):

Stretching three years to five cuts the payment by 31% and multiplies the interest by 1.7. In the first year of the three-year loan you pay 13,093 of its 24,795 interest, 53% of the total.

Each line below is one cash flow: what you get on day one and what you pay over 36 months. The last column is the monthly rate that balances the two, times twelve.

D's lower rate costs 5,538 more than A.

This is an economic cost, not necessarily the legal APR, because rules decide which charges enter it. In the US it reflects the interest rate plus lender fees such as origination charges (CFPB); late fees and application fees charged to every applicant are left out, and a premium for voluntary credit life or disability insurance may be left out if the lender does not require the cover, discloses its cost in writing and you sign for it after that (Regulation Z, 12 CFR 1026.4). Loan C could then show a 15% APR while you still repay 36,027 on top of the cash.

The same loan shows different APRs in different countries. The US APR is the monthly rate times twelve, with no compounding (Regulation Z, Appendix J). The UK APR is an annual compound rate, shown to at least one decimal place (FCA, CONC App 1.2.6R). Loan A is 15.0% APR in the US and 16.1% in the UK. In UK adverts a "representative APR" is a rate the lender expects at least 51% of agreements to get at or below (FCA, CONC 3.5), so it is not a promise of your rate.

What to do

• Ask for the total amount payable and the schedule; compare on the same term and cash in hand.
• Price the version without insurance or add-ons, as with A and D.
• Choose the shortest term your budget can carry.
• Repaying early? If you can choose, shorten the term rather than the payment: in loan A an extra 20,000 after 12 months saves 5,872 of interest that way, against 3,274.
• Changed your mind? UK: you can withdraw from a regulated credit agreement within 14 days, repaying the loan with interest for the days you had it; not for loans over £60,260 (except home improvement) or secured on land (Consumer Credit Act 1974, s.66A). US: the three-day right of rescission covers only some loans secured by your main home and not used to buy it, such as refinancing (CFPB); we found no general cooling-off period for consumer loans. See cooling-off periods.

When this is not the case

• The payment matters more than the total when a short term would break your budget; a missed payment costs more: stress-test your budget, emergency fund.
• Variable rates. The figure is calculated at signing; if the rate moves, the real cost moves with it.
• Mortgages and car finance have their own rules, not covered here: the real cost of a car.
• Cards, refinancing, instalments: same method — minimum payments, refinancing, instalments, buy now, pay later.

See also compound interest and, for loan insurance, how to read an insurance policy.

Sources

• CFPB — Interest rate vs APR (US)
• CFPB — Regulation Z, 12 CFR 1026.4, finance charge (US)
• CFPB — Regulation Z, Appendix J, APR calculation (US)
• CFPB — Right of rescission (US)
• FCA Handbook — CONC App 1.2, APR formula (UK)
• FCA Handbook — CONC 3.5, representative example (UK)
• Consumer Credit Act 1974, s.66A (UK)

Checked: 24 September 2026