Straight-line: In this type of depreciation, you essentially depreciate an equal amount of the value of your property across the useful life of the asset as you’ve estimated it, being sure to account for any salvage value.
Declining value: If you want to more accurately represent on your company's general ledger how your asset is losing value as it ages, the declining value method can be useful. Instead of taking the depreciation in equal parts, you essentially depreciate more in the earlier years and less as it ages, based on the depreciation rate.
Double-declining value: Similar to the declining value method, the double-declining value method allows you to fully depreciate the item at double the rate, as the name implies.
Sum-of-the-years’ digits: Much like declining value, the sum-of-the-years' digits method depreciation allows you to depreciate more value upfront. Instead of using a percentage, you essentially add up the sum of the number of years the item is in service. For example, a three-year item would be 1+2+3, which equals 6. Then, you work backward. In the first year, you depreciate 3/6 of the value, then 2/6, and finally, 1/6.
Units of production. In the units of production depreciation method, you depreciate equipment based on how much it’s been used. If your equipment is capable of producing 10 million units in its lifetime, and the first year it only makes 1 million items, then you’d depreciate 1/10 of the value the first year. If you used it more or less in the second year, you’d adjust accordingly until 10 million units are reached.