Stephen, I agree totally with Mike Webber's comment about not using DSM as a metric to assist your firm. The best way, as Mike has suggested is to first determine your firm's 'true' overhead (total indirect expenses/total direct labor). I use the term 'true' b/c all too often this critical metric is derived by all sorts of other means having nothing to do with the overhead rate. The basis for the two factors in the formula come from the accrual-based profit-loss statement. Preferably, the latest version for the year-end, to-date, 2010. The target range for the overhead rate is 1.30 to 1.50, or 130% to 150%.
Once calculated the break-even rate for the firm is simply 1.00 + the overhead rate, with the 1.00 representing the unit cost of an hour of salary. Therefore, if the overhead rate were calculated as 1.38, the B-E rate would be 2.38, or 238%.
Most of this is explained in detail in the book I co-authored with Michael Tardif, in 2006, titled "Financial Management for Design Professionals: The Path to Profitability".
Respectfully,
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Steve L. Wintner, AIA Emeritus
Founder-Principal
Management Consulting Services
The Woodlands, TX 77380-1414