Why give an allowance as a percentage of blend time?

A thick batch slows mixing throughout, and sampling and hold usually follow blend time, so the extra minutes grow with the batch. At 20% on a 45.5 minute blend, the allowance is 9.1 minutes.

Can this predict the blend time for a new product?

No. Run one full batch at production speed, sample at intervals, and use the minutes between the last two identical results as the proven rate. Then set the allowance from how much longer thick product takes.

What counts toward the available mixing window?

Everything between the start of mixing and the moment the vessel must be released: hold, sampling, a lab check and any planned transfer. Enter the site's committed minutes, not the optimistic ones.

Does a larger batch always need proportionally longer?

Usually, while the geometry and agitator speed are unchanged, because the proven rate is a gallons per minute figure. A taller liquid level or a different impeller changes the rate, so re-measure it after either change.

Process Manufacturing calculator

Batch Mixing Time Calculator

Work out the minutes a batch needs at the rate your vessel proves on this product, then add the viscosity, sampling and hold allowance. The window margin tells you whether the blend finishes before the vessel is wanted.

What this calculator does

Minutes to blend a batch at a proven rate with a viscosity and sampling allowance, checked against the window before transfer.

Formula used

Base mixing time = batch volume ÷ proven blend rate
Required mixing time = base mixing time × (1 + allowance ÷ 100)
Allowance minutes = required mixing time − base mixing time
Window margin = available mixing window − required mixing time

Inputs explained

Batch Volume: Gallons in the batch at mixing temperature, from the batch ticket.
Proven Blend Rate: Rate this product proves out at on this vessel, from records.
Viscosity and Sampling Allowance: Extra blend time for thick product, sampling and the hold.
Available Mixing Window: Minutes before the mix must transfer, from the schedule.

How to use the result

Best suited to scheduling a vessel before transfer, setting a minimum mix hold time, checking a blend against a window.
Blend time is not exactly proportional to volume on every vessel. The model does not check whether the agitator can turn the batch at all.

Current U.S. benchmarks

The producer price index for industrial chemicals stands at 336.006 (BLS, Aug 2026), up 13.3% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 14,543 chemical manufacturing establishments employing about 911,245 workers (Census County Business Patterns, 2023).

Common questions

Why give an allowance as a percentage of blend time? A thick batch slows mixing throughout, and sampling and hold usually follow blend time, so the extra minutes grow with the batch. At 20% on a 45.5 minute blend, the allowance is 9.1 minutes.
Can this predict the blend time for a new product? No. Run one full batch at production speed, sample at intervals, and use the minutes between the last two identical results as the proven rate. Then set the allowance from how much longer thick product takes.
What counts toward the available mixing window? Everything between the start of mixing and the moment the vessel must be released: hold, sampling, a lab check and any planned transfer. Enter the site's committed minutes, not the optimistic ones.
Does a larger batch always need proportionally longer? Usually, while the geometry and agitator speed are unchanged, because the proven rate is a gallons per minute figure. A taller liquid level or a different impeller changes the rate, so re-measure it after either change.

Last reviewed 2026-10-01.