How is estimated annual depreciation expense calculated in the units-of-production method?

In the units-of-production method, estimated annual depreciation expense is calculated based on the expected production from the asset. This method focuses on the output or the actual usage of the asset in terms of its production capacity, making it distinct from methods that allocate expenses based purely on time or original cost.

The calculation starts by determining the total depreciable base of the asset, which is the initial cost minus the residual value. This amount is then divided by the estimated total number of units the asset is expected to produce over its useful life, resulting in a per-unit depreciation rate. Finally, to find the annual depreciation expense, this per-unit rate is multiplied by the actual number of units produced in the accounting period.

This approach aligns the depreciation expense with the asset's actual usage, providing a more accurate reflection of wear and tear. It is particularly useful for manufacturing equipment or similar assets where usage can significantly vary from year to year.