A fixed price budget is easier to calculate than a flexible budget, but it doesn't allow for variable costs. As an example, a landscaping business may have a fixed supply cost, but wages are dependent on the number of hours worked. Flexible budgets allow for such variables, which change according to necessity. In the aforementioned example, a flexible budget might be expressed as a combination of a fixed and flexible budget, such as $2,500 plus $10 per man-hour.
Add the fixed monthly costs. Include any regular costs that do not change. In the example, you might include secretary that only works a set number of hours, payments on machinery and miscellaneous supplies. If you paid your secretary $10 per hour for 40 hours per week, four weeks per month, then her fixed cost is $1,600. If machinery payments and supplies totaled $900 per month, your total fixed costs would be $2,500 per month.
Add all the flexible costs that change with use. In the example, if you only paid wages when you had a customer, then the cost of wages may change dramatically between months. Slow winter months might have no wages, but you might pay six full-time landscapers during the summer. In that case, your flexible costs would be the landscaper wages, such as $10 per hour.
Express your flexible budget as fixed and variable costs. In the example, $2,500 plus $10 per man-hour allows you to calculate a variable monthly budget. On dead winter months, your cost might just be $2,500, because you're paying no landscapers. On prime summer months with six full-time workers, your cost is $2,500 plus $9,600, or a total of $12,100.
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