How do you calculate refill downtime-adjusted run time?

Divide the material to dose by the feeder's dosing rate for base time, then multiply by (1 + allowance). For 120 units at 12 units/hr the base time is 10 hours; a 10% allowance gives 11 hours adjusted.

What should the refill allowance be?

It depends on hopper size and material flow, but 5-15% is common for loss-in-weight feeders. The default 10% adds one hour to a 10-hour base run to cover refill and disturbance windows.

Why add an allowance instead of using base time?

Base time assumes uninterrupted gravimetric dosing. In reality each volumetric refill suspends control briefly, so the true run is longer — here 11 hours instead of 10.

How can I reduce refill downtime?

Use a larger feed hopper or refill vessel to cut refill frequency, improve material flow to reduce disturbances, and time refills during naturally slow windows. Fewer refills means a smaller allowance and a shorter adjusted run.

Refill downtime vs setup time, what's the difference?

Setup time is the one-time changeover before a run; refill downtime is the recurring overhead within the run each time the feeder tops up. Both extend the schedule but come from different sources.

Does dosing rate include the refill losses?

No — enter the feeder's productive dosing rate and let the allowance handle refill overhead. Double-counting by lowering the rate and adding an allowance will over-pad the estimate.

Weighing, Dosing & Loss-in-Weight Feeding calculator

Refill Downtime Calculator

Refill downtime estimates how long a loss-in-weight feeder needs to deliver a batch of material, then pads that base time with an allowance for the volumetric refill windows and flow disturbances that interrupt gravimetric dosing. Schedulers and line leads use it to set realistic completion times rather than assuming the feeder runs uninterrupted at rate. It matters because every refill briefly suspends true gravimetric control, and on a long batch those windows add up to real clock time. Building the allowance into the estimate keeps downstream stations from being scheduled against a run time the feeder can't actually hit.

What this calculator does

Refill downtime estimates how long a loss-in-weight feeder needs to deliver a batch of material, then pads that base time with an allowance for the volumetric refill windows and flow disturbances that interrupt gravimetric dosing.
Use it when refill downtime in weighing, dosing and loss-in-weight feeding needs a defensible run time before a quote goes out.
It computes base run time as material ÷ dosing rate, then multiplies by an allowance factor to include refill and disturbance overhead.

Formula used

Base refill downtime time = required work ÷ processing rate
Adjusted time = base time × allowance factor

Inputs explained

Total material to dose:
Feeder dosing rate:
Refill and disturbance allowance:

How to use the result

Use it when planning how long a loss-in-weight feeder will take to deliver a given amount, accounting for refill interruptions.
The allowance is a flat percentage, so it approximates refill overhead rather than modeling the exact number, duration, and timing of individual refill cycles.

Common questions

How do you calculate refill downtime-adjusted run time? Divide the material to dose by the feeder's dosing rate for base time, then multiply by (1 + allowance). For 120 units at 12 units/hr the base time is 10 hours; a 10% allowance gives 11 hours adjusted.
What should the refill allowance be? It depends on hopper size and material flow, but 5-15% is common for loss-in-weight feeders. The default 10% adds one hour to a 10-hour base run to cover refill and disturbance windows.
Why add an allowance instead of using base time? Base time assumes uninterrupted gravimetric dosing. In reality each volumetric refill suspends control briefly, so the true run is longer — here 11 hours instead of 10.
How can I reduce refill downtime? Use a larger feed hopper or refill vessel to cut refill frequency, improve material flow to reduce disturbances, and time refills during naturally slow windows. Fewer refills means a smaller allowance and a shorter adjusted run.
Refill downtime vs setup time, what's the difference? Setup time is the one-time changeover before a run; refill downtime is the recurring overhead within the run each time the feeder tops up. Both extend the schedule but come from different sources.

Last reviewed 2026-05-12.