Repair or Replace Calculator

How the repair or replace calculator works

The calculator looks at the decision two ways. First, it compares the repair bill with what your car is worth today. Second, it spreads the repair cost over the extra time it buys you and compares that monthly figure with a payment on a replacement car. When both point the same way, you get a clear lean. When they disagree, it calls it a close call and tells you why.

The 50% rule, explained

A common rule of thumb says that if a repair costs more than half of what the car is worth, replacing it deserves a serious look. The logic is simple: spending most of a car’s value to fix it leaves you with an old car and little cushion if something else breaks.

It is a rule of thumb, not a law. A cheap, paid-off car can be worth fixing even past the 50% line, because a replacement brings a payment, higher insurance and new taxes and fees. That is why this calculator also looks at the monthly cost.

We adjust the line for reliability. If the car is reliable apart from this repair, we use 50%. If you know other work is coming, we lower it to 40%. If the car breaks down often, we lower it to 30%, since the next repair is likely not far away.

The math in plain English

• Repair as % of value = repair estimate ÷ car value × 100
• Repair cost per month = repair estimate ÷ (extra years × 12)
• Repair cost per mile = repair estimate ÷ extra miles

In the default example, a $2,500 repair on a $6,000 car is about 42% of its value, under the 50% line but over the 40% line for a car with other known issues. Spread over two years, the repair costs about $104 a month, far less than a $450 payment. So the verdict is a close call that leans toward repairing. These defaults are placeholders, not averages.

Getting good inputs

• Car value: use a private-party or trade-in value from a pricing guide, in its current condition, before the repair.
• Repair estimate: get a written quote, and a second one for big jobs. Ask what else the shop noticed.
• Extra years and miles: be honest about how long the car will last after this fix. A new transmission in a car with a tired engine does not buy many years.
• Replacement payment: use a real quote for the car you would buy, including the loan term you would take.

How to use the result

Treat the verdict as a starting point. Safety comes first: brakes, steering, suspension and wheel bearings are not optional repairs, whatever the math says. Then think about what is not in the numbers, such as how much you rely on the car, whether you can pay cash for the repair and how you feel about taking on a loan.

Want a sense of typical bills first? See our guides to car battery replacement cost, wheel bearing replacement cost and what a flashing check engine light means. If you lean toward replacing, the car ownership cost calculator shows what a new car really costs over the years you own it.

Frequently asked questions

What is the 50% rule for car repairs?

It is a rule of thumb: if a repair costs more than half of the car’s current value, consider replacing the car. It is a quick filter, not a final answer.

Is it better to repair or replace an old car?

Often repairing is cheaper, because a replacement adds a payment, higher insurance and taxes. Replacing makes more sense when repairs are frequent, expensive relative to the car’s value or affect safety.

What if my car is paid off?

A paid-off car has no monthly payment, so repairs often win. Compare the repair cost per month with the payment you would take on and the extra insurance a newer car may cost.

Are my numbers saved?

No. Everything is calculated in your browser and nothing you type is stored or sent.