Straight line depreciation is an accounting concept used to evenly spread the cost of a tangible asset over its useful life. This type of depreciation schedule assumes that an asset has equal economic value during each period of its useful life, and allocates a portion of the purchase price to each period accordingly. It’s the simplest and most common way to calculate depreciation, and it can help businesses plan for the wear and tear their assets will experience. To calculate straight line depreciation, businesses will divide the cost of an asset less its salvage value by the number of years in its useful life. That figure is then subtracted from the asset’s book value every year until it reaches zero or its expected salvage value.