Difference between revisions of "Documentation/How Tos/Calc: DB function"
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: To calculate depreciation, <tt>'''DB'''</tt> uses a fixed rate throughout the asset’s life, given by | : To calculate depreciation, <tt>'''DB'''</tt> uses a fixed rate throughout the asset’s life, given by | ||
− | :: rate = 1 - (salvagevalue/originalcost)<sup>(1/lifetime)</sup> | + | :: <tt>'''rate'''</tt> = 1 - (<tt>'''salvagevalue'''</tt>/<tt>'''originalcost'''</tt>)<sup>(1/<tt>'''lifetime'''</tt>)</sup> |
: rounded to 3 decimal places. | : rounded to 3 decimal places. | ||
: The depreciation in any year is given by | : The depreciation in any year is given by | ||
− | :: value_at_start_of_year * rate | + | :: <tt>'''value_at_start_of_year * rate'''</tt> |
− | : where value_at_start_of_year | + | : where <tt>'''value_at_start_of_year'''</tt> = <tt>'''originalcost'''</tt> - <tt>'''depreciation_so_far'''</tt>. |
− | : If months1styear is less than 12 the depreciation rate used for the first and last years is | + | : If <tt>'''months1styear'''</tt> is less than 12 the depreciation rate used for the first and last years is |
− | :: rate * number_of_months_in_year / 12. | + | :: <tt>'''rate'''</tt> * <tt>'''number_of_months_in_year'''</tt> / 12. |
=== Example: === | === Example: === |
Revision as of 15:57, 12 July 2008
DB
Returns the depreciation of an asset for a given year using the declining-balance method.
Syntax:
DB(originalcost; salvagevalue; lifetime; year; months1styear)
- originalcost: the initial cost of the asset.
- salvagevalue: is the value at the end of the depreciation (sometimes called the salvage value of the asset).
- lifetime: the number of years over which the asset is being depreciated.
- year: the year number for which the depreciation is calculated.
- months1styear: the number of months in the first year (defaults to 12 if omitted).
- To calculate depreciation, DB uses a fixed rate throughout the asset’s life, given by
- rate = 1 - (salvagevalue/originalcost)(1/lifetime)
- rounded to 3 decimal places.
- The depreciation in any year is given by
- value_at_start_of_year * rate
- where value_at_start_of_year = originalcost - depreciation_so_far.
- If months1styear is less than 12 the depreciation rate used for the first and last years is
- rate * number_of_months_in_year / 12.
Example:
DB(10000; 1000; 5; 1)
- returns approximately 3690 in currency units, which is the depreciation in the first year for an asset which cost 10000 and is written down to 1000 over 5 years.
See also:
Derivation of Financial Formulas
Issues:
- This function underestimates depreciation slightly if months1styear is not 12; this is likely to be a standard approach with this method.