How do you calculate lights-out machining capacity?

Multiply unattended parts per cycle by lights-out cycles for gross capacity, then multiply by unattended uptime and lights-out yield. Here 6 x 72 = 432 gross, then x 0.82 x 0.96 = about 340 good parts.

Why is unattended uptime lower than staffed uptime?

With no operator to clear a chip nest, swap a broken tool, or restart after an alarm, a single failure can idle the machine for hours. That is why the 82 percent here is below typical staffed uptime.

What is a realistic lights-out uptime?

Many shops see 75 to 90 percent on proven, well-fixtured unattended jobs. New or risky processes can run far lower until tool-life monitoring and chip control are dialed in. Use measured history, not hope.

How many good parts will I have by morning?

Plan on good capacity, not gross. In the example you would gross 432 but realistically find about 340 good parts, after losing roughly 78 to downtime and 14 to scrap.

How do I make lights-out machining more reliable?

Add tool-life monitoring, in-process probing, chip conveyors and high-pressure coolant, broken-tool detection, and conservative feeds. Each lifts unattended uptime and yield, which flow straight into capacity.

Lights-out vs staffed capacity - what's different?

The math is identical, but lights-out runs use lower uptime and yield because nobody recovers failures in real time. That gap is exactly what this calculator forces you to plan around.

CNC Machining calculator

Lights-Out Machining Capacity Calculator

Lights-out machining capacity is the number of good parts a CNC machine can produce running unattended, typically overnight or through the weekend, with no operator present. Shops that invest in bar feeders, pallet pools, and robotic load/unload use this metric to turn idle off-shift hours into real output. The catch is that unattended uptime and yield are usually lower than staffed running: a crash, a broken tool, or a chip nest can stop the machine for the rest of the night with nobody to recover it. This calculator derates gross unattended capacity by realistic lights-out uptime and yield so you do not over-promise parts that the morning shift finds sitting in alarm.

What this calculator does

Estimate unattended CNC output from pallet capacity, unattended cycles, uptime, and expected first-pass yield.
estimating lights-out machining capacity for production planning, quoting, staffing, or automation review
It computes good unattended-part capacity as parts-per-cycle times lights-out cycles, derated by unattended uptime and lights-out first-pass yield.

Formula used

Gross lights-out machining capacity = unattended parts per cycle × lights-out cycles available
Good lights-out machining capacity = gross capacity × unattended uptime expectation × lights-out first-pass yield

Inputs explained

Unattended parts produced per cycle:
Lights-out cycles available overnight:
Unattended uptime expectation:
Lights-out first-pass yield:

How to use the result

Use it when planning overnight or weekend unattended runs and committing how many good parts will be waiting at the start of the next shift.
A single mid-run failure with no operator can halt all remaining cycles, so a static uptime percentage may understate the risk of an early-night stoppage.

Current U.S. benchmarks

The producer price index for steel mill products stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 17,154 machine shops establishments employing about 223,303 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate lights-out machining capacity? Multiply unattended parts per cycle by lights-out cycles for gross capacity, then multiply by unattended uptime and lights-out yield. Here 6 x 72 = 432 gross, then x 0.82 x 0.96 = about 340 good parts.
Why is unattended uptime lower than staffed uptime? With no operator to clear a chip nest, swap a broken tool, or restart after an alarm, a single failure can idle the machine for hours. That is why the 82 percent here is below typical staffed uptime.
What is a realistic lights-out uptime? Many shops see 75 to 90 percent on proven, well-fixtured unattended jobs. New or risky processes can run far lower until tool-life monitoring and chip control are dialed in. Use measured history, not hope.
How many good parts will I have by morning? Plan on good capacity, not gross. In the example you would gross 432 but realistically find about 340 good parts, after losing roughly 78 to downtime and 14 to scrap.
How do I make lights-out machining more reliable? Add tool-life monitoring, in-process probing, chip conveyors and high-pressure coolant, broken-tool detection, and conservative feeds. Each lifts unattended uptime and yield, which flow straight into capacity.

Last reviewed 2026-05-12.