What minimum gap should I enter for a photo eye?

Use the gap the sensor or device maker specifies for your part and speed. As a reference, PackagingConveyor.com's design guide says sensor-triggered accumulation zones need 1 to 3 inches of gap for photo eye detection.

Why does lower uptime need a faster belt?

To average the same parts per hour, the machine must release parts faster while it runs. At 80% uptime, 900 parts an hour means 1,125 an hour while running, so parts land closer together at any belt speed.

Can I open the gap by speeding up the next belt?

Yes: a faster downstream belt pulls parts apart at the transfer, and the pitch grows by the ratio of the two speeds. Run this check on the belt where the photo eye or robot sits.

What part length do I enter for a mix of parts?

Enter the longest part in the mix. At a given belt speed and rate every part rides at the same pitch, so the longest part leaves the smallest gap.

Conveyors calculator

Part Spacing Conveyor Speed Calculator

Find the slowest belt speed that still leaves the gap your photo eye, reject gate or robot needs between parts. You need the rate, uptime, part length, minimum gap and current belt speed.

What this calculator does

Belt speed that keeps parts at least your minimum gap apart at the rate you need, and whether your belt holds it.

Formula used

Release rate while running = parts needed per hour ÷ (uptime % ÷ 100)
Minimum belt speed (ft/min) = release rate × (part length + minimum gap) ÷ 720; 720 = 12 in/ft × 60 min/hr
Part pitch at belt speed (in) = belt speed × 720 ÷ release rate; gap = pitch − part length
Most parts per hour = belt speed × 720 ÷ (part length + minimum gap) × uptime % ÷ 100

Inputs explained

Parts Needed per Hour: Average parts per hour over scheduled time, from the schedule.
Uptime: Run time ÷ scheduled time for the upstream machine, from downtime logs.
Part Length Along the Belt: Part dimension in the direction of travel, as it rides.
Minimum Gap Between Parts: Smallest gap your photo eye, reject gate or robot handles.
Belt Speed: Current or planned speed, measured at the belt with a tach.

How to use the result

Best suited to setting belt speed ahead of a photo eye, checking spacing before adding a robot pick.
If parts arrive bunched, enter the peak running rate with uptime at 100%. A transfer to a belt at another speed changes the gap: check each belt separately.

Current U.S. benchmarks

The U.S. has 21,668 machinery manufacturing establishments employing about 1,086,146 workers (Census County Business Patterns, 2023).

Common questions

What minimum gap should I enter for a photo eye? Use the gap the sensor or device maker specifies for your part and speed. As a reference, PackagingConveyor.com's design guide says sensor-triggered accumulation zones need 1 to 3 inches of gap for photo eye detection.
Why does lower uptime need a faster belt? To average the same parts per hour, the machine must release parts faster while it runs. At 80% uptime, 900 parts an hour means 1,125 an hour while running, so parts land closer together at any belt speed.
Can I open the gap by speeding up the next belt? Yes: a faster downstream belt pulls parts apart at the transfer, and the pitch grows by the ratio of the two speeds. Run this check on the belt where the photo eye or robot sits.
What part length do I enter for a mix of parts? Enter the longest part in the mix. At a given belt speed and rate every part rides at the same pitch, so the longest part leaves the smallest gap.

Last reviewed 2026-10-01.