Two Numbers, Two Very Different Purposes
If you've ever gotten an appraisal, you may have noticed the number felt oddly high compared to what you'd expect to sell the item for at auction. That's not an accident or a compliment. Appraisers produce different values for different purposes, and knowing which one applies to your situation keeps you from making expensive mistakes.
The two you'll encounter most often are fair market value and replacement cost.
Fair Market Value
Fair market value is the price a willing buyer and a willing seller would agree on, with neither under pressure and both having reasonable knowledge of the facts. It's the number that reflects the actual secondary market: what similar items have sold for at auction, on resale platforms, or through dealers.
This is the number that matters when you're:
- Selling an item
- Distributing an estate among heirs
- Filing for probate or estate tax purposes
- Donating an item and claiming a tax deduction
Fair market value is almost always lower than what you paid and often lower than what you'd see on a retail tag. That's not pessimism; it's how resale markets work.
Replacement Cost
Replacement cost answers a different question: what would it cost to buy an equivalent item new, or to find a comparable piece on the current retail market?
This number is almost always higher than fair market value, sometimes dramatically so. A mid-century sideboard might have a fair market value of $800 at auction but a replacement cost of $2,400 at a design boutique selling comparable new pieces.
Replacement cost is the number that matters for:
- Insurance coverage: your insurer wants to know what it would cost to replace something if it were lost or stolen, not what you'd get selling it
- Estate planning: some contexts require knowing what it would cost to replicate a collection
- Charitable donations of certain types: check with your accountant, but replacement cost can apply in specific scenarios
A Practical Example
Say you find a signed lithograph by a listed artist in your late mother's house. A formal appraisal might give you:
- Fair market value: $1,200 (based on comparable auction results)
- Replacement cost: $3,500 (based on what a gallery charges for a similar work)
If you list the piece for $3,500 because that's what the appraisal document says, you'll wait a long time for a buyer. If you insure it for $1,200, you'll be underinsured if something happens to it.
Neither number is wrong. They're just answering different questions.
What AI Appraisal Tools Provide
Tools like Tappraise give you both numbers for each item you photograph, which is useful for exactly this reason. You can see the gap between what something is worth to sell and what it would cost to replace, and make informed decisions about pricing, insurance, and whether to consult a specialist.
For most items, the two numbers together tell you everything you need to orient yourself. For high-value pieces where the difference is significant, that's a signal to bring in a credentialed appraiser who can produce a formal document your insurer or attorney will accept.
The Rule of Thumb
Selling something? Use fair market value as your anchor.
Insuring something? Use replacement cost.
Donating something? Ask your accountant which applies to your situation before filing.
Getting these confused is one of the most common and most avoidable errors in estate work. Now you won't make it.