How do you calculate annealing lehr capacity?

Multiply containers per cycle by available cycles for gross capacity, then multiply by uptime and post-lehr yield. With 850 per cycle, 22 cycles, 94% uptime, and 98% yield, that is 18,700 x 0.94 x 0.98 = 17,226 good containers.

Why subtract uptime and yield from lehr capacity?

Gross capacity assumes a perfect lehr running every cycle with zero rejects. Uptime trims for stoppages (the example loses 1,122 containers) and post-lehr yield trims for cold-end rejects (another 352), leaving 17,226 saleable containers.

What is post-lehr first-pass yield?

It is the share of containers leaving the lehr that pass cold-end inspection on the first pass, before rework. In the example it is 98%, costing about 352 containers off the uptime-adjusted total.

What happens if glass is not annealed properly?

Containers retain residual stress from the forming process, making them prone to thermal and mechanical breakage at filling or in the field. Correct lehr time and temperature profile are what relieve that stress, so lehr throughput cannot be pushed past safe annealing.

Can the lehr be a bottleneck for the forming line?

Yes. If gross lehr capacity after uptime and yield falls below hot-end forming output, ware backs up or the line slows. Comparing this 17,226-container result to forming output flags whether the lehr is the constraint.

How do I increase good lehr capacity?

Raise uptime by reducing belt and burner stoppages, improve cold-end yield through better forming and handling, or increase containers per cycle with tighter ware loading. Lifting uptime from 94% to 97% alone would add several hundred good containers.

Glass Container & Bottle Manufacturing calculator

Annealing lehr capacity Calculator

Annealing lehr capacity estimates how many good, properly annealed containers a lehr can deliver over a period, after accounting for both lehr uptime and the first-pass yield of ware coming off the cold end. Production planners and quality engineers use it because the lehr is the throughput gate between hot-end forming and cold-end inspection: glass that is not annealed correctly carries residual stress that causes breakage, and the lehr's belt speed and uptime cap how much ware can be relieved of stress per shift. The calculation starts from gross capacity (containers per cycle times available cycles), then trims it by uptime and post-lehr yield to give the realistic count of saleable, stress-relieved containers, which is the number that actually feeds packing.

What this calculator does

Estimate good container capacity through an annealing lehr using containers per lehr cycle, available cycles, lehr uptime, and first-pass yield.
Use it when forming output, lehr speed, belt loading, thermal profile, or cold-end flow must be checked before committing bottle or jar production by shift.
It computes good annealed container capacity as containers per cycle times available cycles, derated by lehr uptime and post-lehr first-pass yield.

Formula used

Gross annealing lehr capacity = containers per lehr cycle × available lehr cycles
Good annealing lehr capacity = gross capacity × annealing lehr uptime × post-lehr first-pass yield

Inputs explained

Containers per lehr cycle:
Available lehr cycles:
Annealing lehr uptime:
Post-lehr first-pass yield:

How to use the result

Use it to confirm the annealing lehr can keep up with hot-end forming output and to plan realistic saleable volume after stress relief and cold-end yield losses.
It assumes a steady containers-per-cycle loading and a single yield figure; checks and chips that show up only after later inspection or filling are not captured by first-pass cold-end yield alone.

Current U.S. benchmarks

Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate annealing lehr capacity? Multiply containers per cycle by available cycles for gross capacity, then multiply by uptime and post-lehr yield. With 850 per cycle, 22 cycles, 94% uptime, and 98% yield, that is 18,700 x 0.94 x 0.98 = 17,226 good containers.
Why subtract uptime and yield from lehr capacity? Gross capacity assumes a perfect lehr running every cycle with zero rejects. Uptime trims for stoppages (the example loses 1,122 containers) and post-lehr yield trims for cold-end rejects (another 352), leaving 17,226 saleable containers.
What is post-lehr first-pass yield? It is the share of containers leaving the lehr that pass cold-end inspection on the first pass, before rework. In the example it is 98%, costing about 352 containers off the uptime-adjusted total.
What happens if glass is not annealed properly? Containers retain residual stress from the forming process, making them prone to thermal and mechanical breakage at filling or in the field. Correct lehr time and temperature profile are what relieve that stress, so lehr throughput cannot be pushed past safe annealing.
Can the lehr be a bottleneck for the forming line? Yes. If gross lehr capacity after uptime and yield falls below hot-end forming output, ware backs up or the line slows. Comparing this 17,226-container result to forming output flags whether the lehr is the constraint.

Last reviewed 2026-05-12.