The straight-line method of depreciation is a commonly used and straightforward method for allocating the cost of a capital asset over its useful life. It is the simplest method for calculating depreciation because it assumes that the asset will decline in usefulness on a constant basis from period to period. The straight-line method is based on the uniform depreciation of an assets value, where the value of an asset is reduced uniformly over each period until it reaches its salvage value. The formula for calculating straight-line depreciation is (cost of the asset - salvage value) / useful life.

To apply the straight-line method, you need to determine the cost basis for the asset, which includes the purchase price of the asset, taxes, shipping and other fees, installation, etc. You should also have a concrete number for the estimated useful life of the asset, as well as its salvage value, if any. The straight-line method is the easiest to compute and can be applied to all long-term assets. However, it does not accurately reflect the difference in usage of an asset and may not be the most appropriate value calculation method for some depreciable assets.

In addition to the straight-line method, there are other methods of calculating depreciation of an asset, such as units of production, sum of the years digits, declining balance, and modified accelerated cost recovery systems (MACRS). However, the straight-line method is the most commonly used in practice because it is the simplest GAAP-compliant method.