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Throughput modeling 101

Throughput modeling 101

Sample article — replace with your real content.

Before you talk to a single integrator, you should be able to answer three questions on a napkin:

  1. What does one unit of throughput actually mean here? (Cases? Pallets? Eaches? Lines?)
  2. What’s the peak hour rate, not the average?
  3. What’s your growth horizon — 3 years? 7? Forever?

If those three numbers are wrong, no amount of mechanical engineering downstream will save the project.

The first-principles formula

[ T_{peak} = \frac{V_{daily} \times P}{H \times U} ]

Where:

  • ( V_{daily} ): daily volume (units/day)
  • ( P ): peak factor (typically 1.4–2.5 depending on industry)
  • ( H ): productive hours per day
  • ( U ): system utilization target (usually 0.7–0.85)

Worked example

Say you’re sizing a small-parts pick line:

  • 12,000 units/day average
  • Peak factor 1.8 (typical e-commerce)
  • 16 productive hours
  • 0.80 utilization target

[ T_{peak} = \frac{12{,}000 \times 1.8}{16 \times 0.80} = 1{,}687.5 \text{ units/hr} ]

You’d size to ~1,700 units/hr peak. Vendors will pitch you a “30,000/day” number — that’s their average, not your peak. Always do the math.

What integrators leave out

The number above is the demand. Integrators quote capacity. The gap between them is filled by:

  • Cycle-time variation — pick stations don’t all run at the same rate.
  • Replenishment dwell — you can’t pick what isn’t there.
  • Operator availability — sick days, breaks, training curves.

Any quote that doesn’t break those out separately is a quote you can’t compare.

  • See AS/RS economics — when does it actually pay? (sample reference article)
  • See Vendor short-list: pick-to-light providers (sample reference article)

Try the throughput calculator on theartoflogistics.com for a quick sanity check.