TAHA Engineering Toolsby TAHA Knowledge Lab

Industrial & Manufacturing

Production Batch Time Calculator

Elapsed time, machine hours and shifts for a batch from set-up, cycle time and quantity.

Inputs

Identical machines sharing the batch, each set up at the same time.

Allows for small stops, breaks within the shift and speed losses. 100% = no losses. An OEE-style figure without the quality loss.

Enter it to see how many shifts the batch needs.

Result

Elapsed time to finish the batch
26.0098
Run time (after set-up)
24.5098
Total machine hours
26.0098
Average time per part, set-up included
187.271
Working
Run time = 500 × 150 s ÷ (1 × 0.85) = 24.51 h Elapsed = set-up 1.5 h + run 24.51 h = 26.01 h Machine hours = 1 × 1.5 + 500 × 150 s ÷ 0.85 = 26.01 h

The batch takes about 26.0098 h from the start of set-up, using 26.0098 h of machine time.

Educational estimate — check the assumptions below.

About this calculator

How long will an order take on the shop floor? A batch needs a set-up (changing tools, fixtures and programs, and making the first good part), then a run of quantity × cycle time. Spreading the batch over several identical machines shortens the elapsed time but adds set-ups. This calculator gives the elapsed time for planning delivery dates, the machine hours for costing, and the average time per part including its share of the set-up.

Formula

Run time = Q × tc ÷ (m × η)    Elapsed time = ts + run time

Machine hours = m × ts + Q × tc ÷ η

Q = batch quantity, tc = cycle time per part, m = machines in parallel, η = efficiency (fraction), ts = set-up time per machine.

Worked example

500 parts, set-up 90 min, cycle 150 s, one machine, 85% efficiency, 7.5 productive hours per shift:

  • Run time = 500 × 150 ÷ 0.85 = 88 235 s = 24.51 h
  • Elapsed = 1.5 + 24.51 = 26.01 h → about 3.5 shifts
  • Average time per part = 26.01 h ÷ 500 = 187.3 s
  • With 2 machines: run time halves to 12.25 h; elapsed 13.75 h; machine hours rise to 27.51 h.

Assumptions and limitations

  • Set-ups on parallel machines are done at the same time. If one setter prepares them one after another, add the extra set-up time.
  • Scrap is not included: increase the quantity to allow for expected rejects (see the scrap and yield calculator).
  • Queues, material waiting time and inspection hold-ups are not included; real lead time is usually longer.

References

  • Batch time = set-up + quantity × cycle time (standard production-planning practice).