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Capacity Requirement Calculator

Enter demand, time per unit and efficiency to size the machine hours you need.

How it is calculated

hours at 100% = demand × minutes per unit ÷ 60 and hours needed = hours at 100% ÷ (efficiency ÷ 100). Demand is the number of units to make, time per unit is the machine time for one unit in minutes, and efficiency is a percent (default 85 if left empty). The result shows both the ideal hours and the hours after the efficiency loss, rounded to one decimal. All three values must be above zero. Efficiency above 100 gives no result. It treats one machine; for several identical machines, divide the hours by their number and by the hours each runs. Working-time rules differ by plant and country.

Worked example

Demand 5000 units, 2.5 minutes of machine time per unit, efficiency 80%. Ideal hours = 5000 × 2.5 ÷ 60 = 12,500 ÷ 60 = 208.3 hr. Divide by 0.80: 208.33 ÷ 0.8 = 260.4 hr. So the job needs about 260 machine-hours, roughly 52 hours more than the ideal figure.

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Common mistakes

  • Entering time per unit in seconds or hours; the field is minutes, so 150 seconds should be typed as 2.5.
  • Entering efficiency as a decimal (0.8). The tool reads it as 0.8%, and the answer jumps to about 26,042 hours.
  • Using 100% because the machine's rated speed is known. The efficiency figure is there for setups, changeovers and breakdowns, so use your measured value.
  • Comparing the result with hours per calendar day instead of the machine's available hours per shift, which gives a false sense of spare capacity.
  • Using the default 85% without thinking, then wondering why the result differs from the plant's own OEE figure.

About this calculator

Capacity requirements planning (CRP) answers a basic operations question: do we have enough machine time to meet demand? The formula is Machine hours needed = (Demand × Time per unit) ÷ Efficiency, where efficiency (usually well under 100%) accounts for setup time, changeovers, breakdowns, and other real-world losses that keep a machine from running at its theoretical rate.

Production planners and operations managers run this calculation when building a master production schedule, comparing the hours required against available machine-hours per shift to spot bottlenecks before they cause missed deliveries. It's a standard step in manufacturing resource planning (MRP II) alongside material requirements planning.

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Comments (1)

  • Editorial team

    The hours are machine hours for the whole run, so convert them to machines for a given period. With the defaults, about 98 hours is roughly 2.45 machines running a 40-hour week, so you would plan for three or stretch into overtime. Count setup and changeover time inside the minutes per unit if they are not otherwise covered. Do you measure efficiency as OEE or something simpler?

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