How do I determine the before and after fair market value of items lost in a fire... like the coffee maker, tv, surge protectors?

[fanfare]

the fair market value of such items after a fire is zero.

[randb324]

What about determining the fair market value before the fire?

[AnnetteB6]

You would need to consider each item's age and condition.  

The fair market value is the amount that a willing buyer would pay for the item and a willing seller would accept as payment.  

@randb324

[Carl]

The value of a property or item before a fire, is usually more than $0. It will be the price a willing buyer would pay, and the seller would accept. For small items, think more like pricing items for a garage sale.

The value of a property or item after the fire is usually $0 if the item was no longer usable for it's intended purpose.

However, that's not true for real estate. Here's why.

When your rental property burns to the ground and is declared a total loss by the insurance company, then it is a total loss for the insurance company. But it's not a total loss for you. You still have the land and that land still retains it's value.  The insurance company has only insured the structure; not the land. So if the house burns to the ground, from the insurance company's perspective, it's a total loss "for them". You don't lose a penny of value in the land.