Version 1.6 · Last updated 2026-11-02 · Changelog
What this is: an estimate of what a dealer is likely to offer for your car on trade, built from real dealer listings near you, with every step shown.
What this is not: an offer, an appraisal, or a guarantee. A dealer inspects the car before making a firm offer, and offers vary between dealers.
We find cars like yours that dealers near you are selling right now, work out what that kind of car sells for at retail, then subtract what a dealer typically needs to make on it and what it costs to get a car in your condition ready to sell. What's left is the trade-in value.
No AI model produces the number. It is a lookup plus arithmetic, and the same inputs on the same day give the same answer. Every step appears as its own line on your result, under "How we got this".
| Step | What we do | Where the number comes from |
|---|---|---|
| 1. Identify the car | Decode the VIN, or match what you typed, to a year, make and model | NHTSA vPIC (U.S. government VIN decoder) |
| 2. Find similar cars | Search used cars of the same year, make and model listed by dealers within 100 miles of your ZIP code. Up to 50 listings are used. | Marketcheck dealer listing data, searched when you ask |
| 3. Adjust to your mileage | Normalize each listing to a common mileage, then move the price to your mileage at a rate fitted on those same listings (or a typical rate when there aren't enough listings to fit one) | The listings |
| 4. Adjust to your trim | If you pick a trim and at least 3 nearby listings share it, use that trim's prices relative to all trims | The listings |
| 5. Retail value | The middle (median) of the adjusted prices. This is the "dealer list price" on your result. | The listings |
| 6. Dealer resale margin | Subtract 7.8% of the retail value | About 5.4% is measured dealer gross profit on a used car: $1,634 per car at 5.4% for public dealer groups (Haig Report, Q2 2026); $1,409 for the average franchised dealer (Presidio-NCM, Q2 2026). That is measured on selling prices. The rest, about 2.4 points, is our estimate of the discount buyers get off the asking prices listings show. What dealers make |
| 7. Reconditioning | Subtract a fixed amount for the condition you pick: excellent $400, good $900, fair $1,900, rough $3,500 | Our estimate. There is no public per-car data for reconditioning cost. |
Trade-in value = retail value − dealer margin − reconditioning.
We use the margin as a percentage, not a flat dollar amount, so a $6,000 car isn't charged the margin on a $30,000 car. On a $30,016 listing (J.D. Power's September 2025 average used retail price) it comes to about $2,340.
The "likely offer" range comes from how spread out the nearby listings are: the middle half of the adjusted listing prices (25th to 75th percentile). It gets wider when:
The same dollar deductions (margin and reconditioning) apply across the range. Picking a trim on the result screen usually makes the range visibly tighter, because the trim term drops out.
If fewer than 5 similar cars are listed by dealers within 100 miles, we say so and don't show a value. We'd rather show nothing than a number we can't back.
Asking price vs. sale price. Listings show what dealers are asking, not what cars sold for. No completed-sale prices are available to us. The closest thing we can measure is the last price a car was listed at before it left the market. In our October 2026 check that was 100.3% of current asking prices (median across 12 models; individual models ranged from 92% to 111%), so we apply no adjustment and add the spread to the range instead. Any discount negotiated off the final listed price is not measured, and we don't invent one.
Condition. Listings don't record condition, so we treat them as cars in good, retail-ready shape. Your condition answer changes only the reconditioning deduction.
Options and packages. Not counted yet. Cars with a rare, expensive package may be worth more than our range.
Region. Built in: every number uses listings within 100 miles of your ZIP, so local prices are already reflected.
How long similar cars have been listed. Your result shows the median number of days the similar cars for sale near you have been listed so far. It comes from the same listings as your value (Marketcheck's "days on market, active", which counts across dealers and starts over if a car is off the market for more than 30 days). We show it only when at least 5 of those listings report it. These cars haven't sold yet, so it tells you how long local supply has been sitting, not how fast a car like yours will sell. It does not change your number.
We tested the listing math (steps 2 to 5) on real Detroit-area listings it hadn't seen, compared against their asking prices (October 2026):
| Test | Listings | Median error | Within 10% | Inside our range |
|---|---|---|---|---|
| Leave-one-out (each listing valued without itself) | 288 | 7.1% | 59% | 60% |
| Unseen listings (next page of results) | 110 | 8.5% | 58% | 65% |
Models with lots of local listings did much better (3–5% median error) than models with fewer than about 15 (16–19%). The range is built to hold about 6 in 10 comparable listings, not all of them.
We have not yet been able to test the trade-in number against real dealer offers. Until we can, treat the margin and reconditioning steps as reasonable averages, not measured facts about your dealer.
In many states, you only pay sales tax on the difference between the new car's price and your trade-in. On a $20,000 trade at a 6% tax rate, that's $1,200 you don't pay. Where we've checked the rules against official state sources, your result shows this savings. A few states (California, Virginia) give no trade-in credit at all; there we say so, because it changes the trade-in vs. sell-it-yourself math.
| State | State rate | Rule we apply | Source |
|---|---|---|---|
| California | 7.25% | No trade-in credit: tax is on the full price, so we show no savings | cdtfa.ca.gov |
| Florida | 6% | Full trade value; county surtax can add a little more | floridarevenue.com |
| Georgia | 7% | Full trade value (title tax (TAVT), not sales tax); the trade-in has to be listed on the bill of sale | dor.georgia.gov |
| Illinois | 6.25% | Full trade value; local tax can add a little more | tax.illinois.gov |
| Indiana | 7% | Full trade value | in.gov |
| Iowa | 5% | Full trade value (fee for new registration, not sales tax) | legis.iowa.gov |
| Kentucky | 6% | Full trade value (motor vehicle usage tax, not sales tax) | revenue.ky.gov |
| Maryland | 6.5% | Full trade value (vehicle excise tax, not sales tax) | mva.maryland.gov |
| Massachusetts | 6.25% | Full trade value; it applies only if sales tax was paid on the car you trade in | mass.gov |
| Michigan | 6% | Credit capped at $12,000 of trade value in 2026; the cap rises $1,000 each January and ends in 2029 | legislature.mi.gov |
| Minnesota | 6.875% | Full trade value (motor vehicle sales tax, not sales tax) | dps.mn.gov |
| Missouri | 4.225% | Full trade value; local sales tax adds more, so the real savings are higher | revisor.mo.gov |
| New Jersey | 6.625% | Full trade value | nj.gov |
| New York | 4% | Full trade value; county and city sales tax add more on top, so the real savings are higher | tax.ny.gov |
| North Carolina | 3% | Full trade value (highway use tax, not sales tax) | library.ncleg.gov |
| Ohio | 5.75% | Only when the car you buy is new; local tax can add a little more | tax.ohio.gov |
| Pennsylvania | 6% | Full trade value; Allegheny County (+1%) and Philadelphia (+2%) add more | pa.gov |
| Rhode Island | 7% | Full trade value; a vehicle registered as a truck doesn't count as a trade-in there | rules.sos.ri.gov |
| Tennessee | 7% | Full trade value; local tax only covers the first $1,600 of the price | tn.gov |
| Texas | 6.25% | Full trade value | comptroller.texas.gov |
| Virginia | 4.15% | No trade-in credit: tax is on the full price, so we show no savings | dmv.virginia.gov |
| Washington | 6.5% | Full trade value; the state's extra 0.5% motor vehicle sales tax and local tax add more, so the real savings are higher | dor.wa.gov |
| Wisconsin | 5% | Full trade value; local tax can add a little more | revenue.wi.gov |
We use the state rate only, so the savings shown is usually a floor. Each state links to the state law or tax agency page we checked. Other states: we show nothing until we've checked them. Each state's rule, with worked examples, is on Trade-in sales tax by state.
Your result already shows the main trade-off in dollars:
If your loan payoff is higher than the trade-in value, the difference is called negative equity. Enter your payoff under "Still making payments?" on your result and we show the gap for your car. The full guide to owing more than it's worth.
The difference doesn't go away at a trade-in. A dealer can pay off your old loan and add what's left to the new one, so you pay it again, with interest, for the life of the new loan. On your result we show what that costs per month and in total, using the average terms for these loans in the Consumer Financial Protection Bureau's data (73 months at a 7.7% contract rate). That is an example, not a quote: your rate and term will differ.
What the federal data shows (CFPB, Negative Equity in Auto Lending, June 2024, loans made 2018 to 2022):
Your options, from the CFPB's and the Federal Trade Commission's consumer advice:
Your result's "Sell now or wait?" panel puts a number on one cost of waiting: miles.
What it leaves out: cars also lose value as they age, and a new model year can pull prices down. Those come on top of the miles, so the panel shows the smallest part of the cost of waiting, not all of it. More: When is the best time to sell?
A firm offer depends on things we can't see from a form:
The closer your condition answer matches what the dealer finds, the closer the offer will be to our range. If the appraiser rates your car one condition step lower than you did, the offer drops by about the difference between our reconditioning amounts for those two steps ($500 between excellent and good, $1,000 between good and fair, $1,600 between fair and rough). Your result's "Before you go to the dealer" panel shows this for your car. Reported accidents and branded titles are among the most common reasons a trade-in number changes. What dealers check, in detail.
Before you go:
| Input | Sourced | Our call |
|---|---|---|
| Nearby retail prices | ✅ Dealer listings within 100 miles (Marketcheck) | — |
| Mileage adjustment | ✅ Fitted on the same listings | Typical rate used when a model has too few listings |
| Dealer margin, 7.8% of retail | ✅ ~5.4% dealer gross (Haig Report, Presidio-NCM, Q2 2026) | ✅ ~2.4 points for the discount off asking prices; applying it as a percentage |
| Reconditioning by condition | — | ✅ All four amounts |
| Range width | ✅ Spread of the nearby listings | ✅ The widening terms and their sizes |
| Minimum of 5 listings | — | ✅ |
| Trade-in tax rules | ✅ Official state tax agency sources | State rate only |
Is it better to sell my car now or wait until spring? On average, spring pays: Cox Automotive's long-term averages show what dealers pay rising 3.4% in March and 1.3% in April, and falling most in October (down 1.5%). For a typical driver that seasonal rise has outweighed the miles added while waiting, but the car also gets older, and in any one year the market can go the other way. Your result puts both in dollars for your car: what the next three months usually do, and what three months of miles at your pace cost.
How is this different from KBB or Edmunds? We show how the number was built: which listings, which adjustments and how much each one moved the price. If a step is our own estimate rather than measured data, we label it.
Is this an offer to buy my car? No. It's an estimate of what a dealer is likely to offer. Only a dealer who inspects the car can make a firm offer.
Why is the trade-in value lower than the dealer list price? The dealer has to recondition the car and resell it at a profit. We subtract a dealer margin of 7.8% of the list price (about 5.4% measured dealer gross profit, plus our estimate of the discount off asking prices) and a reconditioning cost for the condition you chose. What dealers make on a used car.
Why can't you value my car? If fewer than 5 cars like yours are listed by dealers within 100 miles of your ZIP code, we don't have enough local data to give an honest number, so we don't show one.
Does my ZIP code change the value? Yes. We only use listings within 100 miles of your ZIP code, so the number reflects your local market.
How much sales tax does trading in save? In states that tax only the price difference, you save your state's sales tax rate times your trade-in value. Michigan caps the credited amount and Ohio only allows it when buying a new car. Your result shows the savings for the states we've verified.
What should I bring to a trade-in appraisal? The title, or your lender's name and account number if you still owe money on the car, plus the registration, every key and fob, service records and photo ID. Check for open safety recalls with your VIN at NHTSA.gov/recalls first; recall repairs are free.
What happens if the dealer rates my car's condition lower than I did? The offer drops by about the extra reconditioning the dealer expects. With our estimates that's about $500 from excellent to good, $1,000 from good to fair, and $1,600 from fair to rough.
What does "median days listed" mean on my result? Half of the similar cars for sale near you have been listed fewer days than that, half more, counted until the day you checked. It describes cars still for sale, so it is not a time-to-sell estimate, and it doesn't change your value.
Can I trade in a car I owe more on than it's worth? Yes. The dealer pays off your loan and adds the difference to your new loan, so you still pay it, with interest. In federal data, loans that carried a trade-in balance averaged a $626 monthly payment against $496 for trade-ins with equity. Paying the difference in cash, waiting until you owe less, or selling privately avoids that.
Do you use AI to calculate the value? No. The value is arithmetic on real listings. The same inputs on the same day give the same result.
docs/methodology-curve-v0.1.md.How we calculate it · Trade-in tax by state · What dealers make · Trade in or sell? · What dealers check · Owe more than it's worth? · When to sell · Selling a car by state · Stop calls & texts