Obviously, you want to use your equipment as efficiently as possible. Using equipment that is old and outdated can be just as cost-prohibitive as using expensive, over-sized equipment that is unnecessary for your acreage. A tool like a machinery cost calculator (like this Iowa State University "Estimating Farm Machinery Costs" calculator found under the Machinery heading) can help determine your cost per acre. Calculators like these can help you determine fixed and variable costs, depreciation, and cost benchmarks.
A machinery cost calculator is also helpful in the decision making process of buying equipment. Is buying new, used, or leasing your best option? You might also determine that a new machine just isn't in your budget, but it is a necessary tool in your farm operation. You can use your machinery cost calculator to find out if other options like sharing, renting, or custom work are feasible.
As a farm owner, have you calculated your machinery costs lately? When buying new equipment, have you used this calculation? Have you had to re-evaluate how you use certain machines because the cost per acre was higher than you expected?