Estimate what an insurance company would pay based on replacement cost minus depreciation.
Actual Cash Value (ACV) is what an insurance company pays for a damaged or stolen item under an ACV policy. It's the replacement cost minus depreciation — essentially what the item was worth at the time of loss.
ACV policies pay what the item was worth (depreciated). Replacement cost policies pay what it costs to buy a new equivalent item. Replacement cost coverage costs more in premiums but pays significantly more on claims.
A 4-year-old laptop that costs $2,000 new with a 10-year lifespan: ACV = $2,000 − (4 × $190/yr depreciation) = $1,240. The insurance would pay $1,240, not $2,000.