APR vs Interest Rate: What Each Number Includes

An interest rate prices the money. It is the figure that drives the payment arithmetic: cut it into months, charge it on whatever is still owed, repeat. An APR is designed to price the deal, by expressing the interest together with certain other costs as one yearly figure so two offers can be compared on a single number. Which costs are included is set by rules rather than by a lender's preference. The practical consequence is that an offer with a low rate and heavy up-front costs can compare worse than an offer with a higher rate and none, and the comparison figure is the number built to reveal that.

What each number is doing

The row that carries the most information is the last two together. If an offer's two numbers are close, there is little else being charged. If they are far apart, something else is being charged and the paperwork will say what.

The worked example: what a rate does to a total

Same amount, same months, two practice rates. This is the interest rate doing its job.

The higher practice rate charges 3.45x the interest on identical money over identical months. The whole difference shows up as $70.53 a month, which never once looks like $4,232.04 while it is happening. That is the single most important sentence about rates, and it is why the total belongs in every comparison.

How a yearly rate becomes a monthly charge

A rate is a year-sized word. A payment is a month-sized number. The conversion is short.

• Take the yearly rate: practice 22.15%.
• Cut it across twelve months: 1.8458%.
• Apply it to what is still owed: on $9,000.00 that is $166.13 in month one.
• Whatever is left of the payment reduces the debt: $83.21.
• Write the new balance, $8,916.79, and run the same four steps again.

The charge lands on what is left, not on what you took out. That is why the same rate produces a smaller charge every month with nobody renegotiating anything, and it is the mechanism behind every amortization schedule ever printed.

Where the two numbers separate

Costs that are part of getting the money, rather than part of using it, are the reason a comparison figure exists at all. Depending on the kind of borrowing and the rules that apply, that can include origination costs, certain required charges, and money paid up front to reduce a rate.

Money paid at closing to lower a rate is the clearest example of a trade with a break-even inside it: how many months of the smaller payment add up to the check. Under that many months, the cash was better kept. The answer depends entirely on how long anybody stays, which is a fact about your life rather than about the offer.

Comparing two offers properly

1. Match the amount. Two offers for different amounts are not comparable, however similar the rates.
2. Match the term. Same rate, longer term, more total. Always.
3. Read both published numbers on each offer. The gap between them tells you whether there are other costs.
4. Compute both totals. Payment times number of payments, minus the amount borrowed.
5. Ask what happens at the end of any promotional period. That is written in the agreement, not in the headline.

Steps one and two catch most bad comparisons before they start. Pricing any loan offer works the total-cost arithmetic out on three different terms, and the spread between the shortest and the longest on identical money is $1,066.41.

When there is no rate quoted at all

Plenty of borrowing is priced as a flat fee for a short period, with no yearly figure in sight. That is not necessarily hiding anything, but it is unreadable next to anything else until it is converted.

The conversion is one step: divide the fee by what actually reached your hand, then multiply by 365 over the number of days. On practice figures, a $56.25 fee on $375.00 for 14 days is 15.00% for the term and 391.07% written per year. The one-step conversion runs four of them side by side.

Fixed and variable, and why the word matters

A rate that can move is a different product from one that cannot, even when the two are quoted at the same number today. Whether a rate is fixed for the life of the borrowing, fixed for a period and then not, or able to move from the start is written in the agreement rather than in the advertisement.

Two questions settle it. What can cause this rate to change, and what is the most it can change by, over what period. Both have answers in the paperwork, and an offer whose answer to either is vague is an offer you have not finished reading.

The reason this matters more than it looks is the arithmetic already on this page. On identical money over identical months, moving from one practice rate to another changed the price of the money from $1,728.25 to $5,960.29. A rate that can move is a total that can move, and the schedule you were shown assumed it did not.

Promotional rates and what happens at the end

A rate that applies for a window is genuinely useful and it has an ending, and the ending is where the detail lives. What rate applies afterwards, whether anything is charged retrospectively if a balance survives the window, and what happens if a payment is late during it are all written in the agreement.

Some agreements charge from the original date if a balance is still there at the end of the promotional period. That is a specific term with a specific effect, and it is the single most important sentence to find before treating a promotional rate as free money. Read the clause, and if it is unclear, ask the issuer in writing rather than assuming.

What a quoted rate is not

• Not a fact about you until it is offered to you. An advertised figure is available to somebody, and whether that somebody is you is decided by a file and by the deal.
• Not fixed unless it says so. Whether it can move, and on what basis, is in the agreement.
• Not the whole cost of a purchase. On secured borrowing there are costs on the day that no rate ever touches.
• Not comparable across different terms. Same rate, different lengths, different deals.

Where the rate stops being the main character

On borrowing backed by a specific thing, two facts price the deal together: how the borrower has handled money before, and how much of the deal a lender could recover from the thing itself. That second one is why cash handed over on the day changes the price of the money and not just the payment. On the practice car in this series the spread across three deposits is $201.64.

On long borrowing, the rate's effect compounds in a way that is genuinely hard to picture until it is drawn. One thirty-year schedule read at four moments shows what a practice rate does across 360 payments, and the share of each payment that moves the balance at the start is the number most people find hardest to believe.

Going further

How Credit Works prices one amount at two practice rates, one rate at three lengths, one car at three deposits and one fee four ways, all simulated month by month. No lender is named anywhere in its pages and no rate in it is described as typical, average, current or market, because none of them is.

For guidance on what published figures must include where you live, consumerfinance.gov is the authority and it is free.