What is a flexible budget?

Definition of a Flexible Budget
A flexible budget is a budget that adjusts or flexes with changes in volume or activity. The flexible budget is more sophisticated and useful than a static budget. (The static budget amounts do not change. They remain unchanged from the amounts established at the time that the static budget was prepared and approved.)

For costs that vary with volume or activity, the flexible budget will flex because the budget will include a variable rate per unit of activity instead of one fixed total amount. In short, the flexible budget is a more useful tool when measuring a manager's efficiency.

Example of a Flexible Budget
Let's assume a company determines that its cost of electricity and supplies will vary by approximately $10 for each machine hour (MH) used. It also knows that other costs are fixed costs of approximately $40,000 per month. Typically, the machine hours are between 4,000 and 7,000 hours per month. Based on this information, the flexible budget for each month would be $40,000 + $10 per MH.

Now let's illustrate the flexible budget by using different levels of volume. If 5,000 machine hours were necessary for the month of January, the flexible budget for January will be $90,000 ($40,000 fixed + $10 x 5,000 MH). If the machine hours in February are 6,300 hours, then the flexible budget for February will be $103,000 ($40,000 fixed + $10 x 6,300 MH). If March has 4,100 machine hours, the flexible budget for March will be $81,000 ($40,000 fixed + $10 x 4,100 MH).