This article describes the formula syntax and usage of the SYD function in Microsoft Excel.
Description
Returns the sumofyears' digits depreciation of an asset for a specified period.
Syntax
SYD(cost, salvage, life, per)
The SYD function syntax has the following arguments:

Cost Required. The initial cost of the asset.

Salvage Required. The value at the end of the depreciation (sometimes called the salvage value of the asset).

Life Required. The number of periods over which the asset is depreciated (sometimes called the useful life of the asset).

Per Required. The period and must use the same units as life.
Remarks
SYD is calculated as follows:
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Data 
Description 

$ 30,000.00 
Initial cost 

$ 7,500.00 
Salvage value 

10 
Lifespan in years 

Formula 
Description (Result) 
Result 
=SYD(A2,A3,A4,1) 
Yearly depreciation allowance for the first year (4,090.91) 
$4,090.91 
=SYD(A2,A3,A4,10) 
Yearly depreciation allowance for the tenth year (409.09) 
$409.09 