How this calculator works
Straight-line depreciation spreads the cost of an appliance evenly over the number of years it is expected to last. The annual rate is one divided by the service life, so a 12 year appliance loses about 8.3 percent of its replacement cost each year. The value today is the replacement cost minus the amount of life already used, and it stops at zero once the appliance passes its expected life. Working in the other direction, the age, the replacement cost and the current value together imply how long the appliance is expected to last.
Formula
annual rate = 1 / service life. value today = replacement cost x max(0, 1 - age / service life). depreciation to date = replacement cost - value today. implied service life = age / (1 - current value / replacement cost).
Worked example
A refrigerator with an 11 year service life costs $1,400 to replace and is 5 years old. The annual rate is 1/11, or 9.09 percent. The value today is 1,400 x (1 - 5/11) = $763.64, so $636.36 has been written off. If the same refrigerator were worth $600 today, the implied life would be 5 / (1 - 600/1,400) = 8.75 years.
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Frequently asked questions
Is straight-line depreciation the same as what an insurer uses?
No. Insurers usually apply actual cash value, which reflects age, condition and local resale prices. This page gives an even, predictable estimate; use a quote or a valuation for a claim.
Why does the value never go below zero?
The straight-line model stops at the end of the expected life. In practice an old appliance may still have scrap or resale value, so treat the result as a planning figure rather than a market price.
Which service life should I use for an appliance not on the list?
Choose "Enter a service life" and use the number from the manufacturer manual or the warranty length. The defaults come from the InterNACHI life expectancy chart, which reports ranges for many appliances.
Does maintenance change the rate?
The default rates assume normal wear and regular recommended maintenance. Heavy use or a poorly maintained appliance will usually depreciate faster than the table suggests.