Cash vs Financing Purchase Calculator

How it works

Financing turns one price into a stream of monthly payments. Unless the rate is a true 0%, the total of those payments is more than the cash price, and the gap is the cost of borrowing. The calculator finds the standard amortized payment, adds up every installment, and subtracts the cash price:

• cash price — what the item costs paid in full today
• APR — the annual interest rate on the financing
• months — how many monthly payments you make

With the defaults, financing $1,200 at 15% APR over 12 months works out to about $108.31 a month, or $1,300 in total. That is roughly $100 more than paying cash, the price of spreading the purchase out over a year.

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A worked example: financing a $1,200 laptop

You are eyeing a $1,200 laptop and the store offers to split it into monthly payments at 15% APR over 12 months. Each payment is $108.31, so you hand over $1,300 by the end. Financing that purchase costs $100 more than paying cash up front.

The gap grows the longer you stretch it. Keep the same price but spread it over 36 months instead of 12, and the extra jumps to $298 over cash, a difference of $198 just from the longer term. More months means more interest, even at the same rate.

If you have the cash and the purchase is not urgent, paying outright is the cheaper path here by $100. Try your own price, rate, and payment count to see whether financing is worth the convenience.

When financing is worth the extra

• A genuine 0% offer is free money, if you finish in time. Paying over the promo period at no interest lets your cash stay put. Just clear the balance before the rate reverts, or the back-interest can wipe out the benefit.
• Compare the extra cost to keeping your cash. Paying $100 to hold onto $1,200 for a year is only worth it if that cash is doing something more valuable, like covering an emergency or earning more than the interest costs.
• Longer terms lower the payment but raise the total. Stretching the same purchase over more months shrinks each payment while quietly increasing what you pay overall. Watch the total, not just the monthly figure.

A second example, worked

Change the deal and the gap changes with it. Finance $2,000 at 20% APR over 24 months and the payment is about $101.79, totalling roughly $2,443, so financing adds about $443 over paying cash. Stretch the same $2,000 at 20% to 36 months and each payment drops to around $74.33, but the total climbs past $2,675, so the longer term costs more even though the monthly bill looks easier.

• Add up the payments, subtract the cash price. The difference is the interest, the true cost of spreading it out.
• A lower payment is not a cheaper deal. Longer terms shrink the monthly figure while raising the total you hand over.
• Rate and term together set the cost. Watch both, not just whichever one the seller puts in front of you.

What drives the extra cost

Two levers decide how much financing adds on top of the price: the interest rate and the length of the term. Push either one up and the extra cost rises, though they work in different ways. The rate sets how fast interest builds; the term sets how long it keeps building.

• Higher APR, more interest. At a fixed term, every extra point of rate adds directly to what you repay.
• Longer term, more total interest. Even at the same rate, more months mean the balance sits around longer accruing interest.
• A true 0% breaks the link. With no rate, the term no longer adds cost, so the only question is whether you clear it in time.

Reading a financing offer’s fine print

The headline rate is not the whole offer. Store and card financing often carry conditions that can cost far more than the advertised APR suggests, and the worst of them hide inside promotional deals that look free at a glance.

• Deferred interest. A no-interest-if-paid-in-full plan charges interest back to the purchase date if any balance remains when the promo ends, which can be a large lump sum.
• Fees and add-ons. Account-opening charges, payment-protection insurance, or processing fees raise the real cost above the rate alone.
• Minimum payments that miss the deadline. Paying only the minimum on a promo balance can leave a chunk unpaid when the offer expires, triggering the back-interest.

Cash and the opportunity cost of using it

Paying cash avoids all interest, but it also pulls that money out of your account. The right call depends on what the cash would otherwise do. If it is your emergency buffer or could earn more than the financing costs, spreading the purchase out can be the smarter move even at a small rate.

• Keep an emergency fund intact. Draining your cushion to dodge a modest interest charge can backfire the moment an unexpected bill lands.
• Compare the rate to what your cash earns. If savings pay more than the loan charges, financing at a low rate can leave you ahead.
• When neither applies, pay cash. If the money is spare and earning little, clearing the purchase outright skips the extra cost entirely.