COMPARISON · MONEY · CARS
Your car needs a $2,400 repair and averages $1,800 a year in upkeep — or you could buy an $18,000 replacement financed at 8% APR. Over 5 years, repairing costs $11,400 and replacing costs $20,085.80: repairing wins by $8,685.80. Enter your own numbers below — the break-even line tells you exactly how bad the upkeep has to get before replacing wins.
The repair path pays the bill plus yearly upkeep. The replace path sells the car as-is, finances the difference, and pays the new car’s upkeep plus the insurance jump. The verdict names the cheaper side and the dollar gap.
Repair path = repair bill + horizon × yearly upkeep. Replace path = (price − as-is value) + loan interest + horizon × (new upkeep + insurance increase). As-is value = max(0, car value − repair bill) — nobody pays full value for a car that needs work. At the defaults: as-is = $5,600, so the $12,400 loan at 8% APR over 60 months costs $251.43/mo = $15,085.80 total ($2,685.80 interest). Repair path: $2,400 + 5 × $1,800 = $11,400. Replace path: $12,400 + $2,685.80 + 5 × $600 + 5 × $400 = $20,085.80. Repair wins by $8,685.80.
Setup: car worth $8,000, facing a $2,400 repair, averaging $1,800/yr in upkeep; replacement costs $18,000 at 8% APR over 5 years, with $600/yr upkeep and a $400/yr insurance increase.
The as-is value. max(0, 8,000 − 2,400) = $5,600 — the most you can expect selling it with the repair undone. (In practice, buyers discount even more than the bill — see the accuracy note.)
The loan. 18,000 − 5,600 = $12,400 financed. At 8% APR over 60 months the payment is $251.43/mo; 60 payments total $15,085.80, of which $2,685.80 is interest.
The repair path. $2,400 now + 5 × $1,800/yr = $11,400.00. Simple, no interest, no new insurance.
The replace path. $12,400 principal + $2,685.80 interest + 5 × $600 upkeep + 5 × $400 insurance = $20,085.80.
The verdict: $20,085.80 − $11,400.00 = $8,685.80 — repair wins. The replacement’s interest and insurance jump do most of the damage.
The break-even. ($20,085.80 − $2,400) ÷ 5 = $3,537.16/yr — the current car’s yearly upkeep would have to nearly double, to $3,537.16, before replacing ties. Below that, repair wins; above it, replace.
Branch — the $12,000 flip case: same car, but the repair bill is $12,000 and yearly upkeep $3,000, with a cheaper $10,000 replacement. As-is value = max(0, 8,000 − 12,000) = $0 — the car is worthless unrepaired. Loan = $10,000 → $202.76/mo, $12,165.60 total, $2,165.60 interest. Repair path: 12,000 + 5 × 3,000 = $27,000.00. Replace path: 10,000 + 2,165.60 + 3,000 + 2,000 = $17,165.60. Replace wins by $9,834.40. When the repair exceeds the car’s value, the math flips hard.
| Output | Formula | What it means |
|---|---|---|
| As-is sale value | max(0, car value − repair bill) | $5,600 at the defaults — what the broken car realistically sells for. |
| Loan amount | replacement price − as-is value (min $0) | $12,400 at the defaults — what you actually finance. |
| Monthly payment | standard amortization, loan term = horizon | $251.43/mo at the defaults — 60 months at 8% APR. |
| Total loan payments | monthly × months | $15,085.80 at the defaults — every dollar leaving for the loan. |
| Loan interest | total payments − loan | $2,685.80 at the defaults — the price of borrowing. |
| Repair-path total | repair bill + horizon × yearly upkeep | $11,400.00 at the defaults — 5 years of keeping the car. |
| Replace-path total | loan + interest + horizon × (new upkeep + insurance Δ) | $20,085.80 at the defaults — 5 years of the new car. |
| Verdict & gap | cheaper side, by |replace − repair| | Repair by $8,685.80 at the defaults — the number to decide on. |
| Break-even upkeep | (replace total − repair bill) ÷ horizon | $3,537.16/yr at the defaults — the upkeep level that would flip the verdict. |
The as-is value is optimistic: max(0, value − repair bill) assumes buyers deduct exactly the repair cost, but dealers and private buyers typically discount more than the bill — they price in hassle, hidden damage, and their own profit. Get a real as-is offer (CarMax, Carvana, a dealer) and enter the truth. Reliability and safety are not priced: a car that strands you on the highway or fails inspection has costs beyond the repair bills — missed work, tow trucks, and risk. End-of-horizon resale is ignored on both sides: after 5 years the replacement (bought for $18,000) is still worth something, and so is the repaired car — the model compares 5-year cash outflows, not net ownership cost, which flatters the repair side slightly. Repair estimates are guesses: the $1,800/yr upkeep average is the single most uncertain input — if your car is entering its “everything wears out at once” years, be honest and raise it. The loan assumes full financing of (price − as-is) at the stated APR with the term equal to the horizon; a bigger down payment or shorter term changes the interest. Payment is quoted rounded down to the cent, the way lenders state it.
Bright Side Kit. "Repair vs Replace Car." https://brightoolbox.com/repair-vs-replace-car/ Accessed October 23, 2026.The rule of thumb says don’t spend more than 50% of the car’s value on a single repair — a $2,400 repair on an $8,000 car is 30%, so it passes. But the rule ignores your horizon, the replacement’s financing cost, and insurance. The calculator’s $3,537.16/yr break-even is the honest version: it prices everything the rule waves away.
Usually repair it first — as-is buyers discount more than the repair bill, because they price in hassle, hidden damage, and profit. Our model’s as-is value (value − bill = $5,600) is the optimistic ceiling; a dealer’s real offer will be lower. Get a CarMax/Carvana quote before deciding.
It’s the yearly upkeep level where both paths cost the same: ($20,085.80 − $2,400) ÷ 5 = $3,537.16. If your car truly needs less than that per year in repairs, keeping it wins. If it needs more — the “everything breaks at once” years — replacing wins. Track your receipts; the average is the input that matters.
Yes — the yearly insurance increase input (default $400/yr = $2,000 over 5 years). It’s the most-forgotten cost: a financed replacement usually requires full coverage, while an old paid-off car can carry liability only. Get a real quote before you buy.
Enter 0% APR — the loan math becomes principal ÷ months with no interest, so the replace path drops by the full $2,685.80 of interest. At the defaults that still leaves replacing at $17,400 vs $11,400 to repair — cash helps, but it doesn’t erase depreciation.
Depreciation already happened. The $8,000 car already took its big value hit; the $18,000 replacement is about to take its own while you pay $2,685.80 in interest for the privilege. Repairing wins whenever the old car’s upkeep stays under the $3,537.16/yr break-even.
Not in the math — and they should be in your decision. A car that strands you, fails inspection, or lacks modern safety features (automatic emergency braking, blind-spot monitoring) carries costs and risks no spreadsheet prices. If the car is unsafe or untrustworthy, replace it regardless of what the calculator says.