How do you calculate agitator tip speed?

Multiply the impeller diameter by the shaft speed and by pi. A 3.5 ft impeller at 120 rpm gives 3.5 x 120 x 3.1416, or about 1,319 ft/min.

What is a good tip speed for mixing?

It depends on the product: gentle blending of shear-sensitive fluids might target 500-1,000 ft/min, while high-shear dispersion can run several thousand. Match the tip speed that worked at lab scale.

Why hold tip speed constant during scale-up?

Constant tip speed keeps the maximum shear rate near the blade roughly the same between vessels, which protects shear-sensitive products and reproduces dispersion quality from lab to plant.

What's the difference between tip speed and rpm?

RPM is rotational speed of the shaft; tip speed is the linear velocity at the blade edge and depends on diameter too. A larger impeller at lower rpm can match a small one at high rpm.

When do I use the correction factor?

Set it to 1 for a direct calculation. Use a value other than 1 only to apply a drive/gearbox ratio effect or a unit conversion; the default of 1 leaves the result unchanged at about 1,319 ft/min.

Is higher tip speed always better?

No. High tip speed increases shear, which helps dispersion but can degrade emulsions, break crystals, or damage shear-thinning polymers. Match the product's tolerance rather than maximizing.

Process Manufacturing calculator

Agitator Tip Speed Calculator

Agitator tip speed is the linear velocity of the outer edge of an impeller blade, and it is one of the most important scale-up and shear parameters in mixing. Process and formulation engineers watch it because tip speed governs the shear a product sees: too low and you get poor blending or incomplete dispersion, too high and shear-sensitive emulsions, crystals, or shear-thinning polymers can be damaged. Because tip speed is often held constant between a lab mixer and a production vessel, it is the go-to metric for scaling a recipe without wrecking the product. This calculator turns impeller diameter and shaft rpm into a clean feet-per-minute number, with room for a drive or unit correction.

What this calculator does

Estimate agitator tip speed from impeller diameter, rotational speed, and unit conversion.
checking whether an agitator speed is reasonable for a blend, dispersion, or shear-sensitive product
It computes impeller tip speed in ft/min as diameter times shaft speed times pi, with an optional correction multiplier.

Formula used

Tip speed = impeller diameter × agitator speed × circumference factor × correction
Use the correction only for unit conversion or drive ratio effects.

Inputs explained

Impeller diameter:
Agitator shaft speed:
Pi (circumference constant):
Drive ratio or unit correction:

How to use the result

Use it when scaling a mixing process up or down, matching shear between vessels, or checking that a shear-sensitive product isn't over-agitated.
Tip speed alone doesn't capture pumping capacity or overall power input; two impellers at the same tip speed can deliver very different flow and blend times.

Current U.S. benchmarks

The producer price index for industrial chemicals stands at 344.336 (BLS, May 2026), up 16.1% 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

How do you calculate agitator tip speed? Multiply the impeller diameter by the shaft speed and by pi. A 3.5 ft impeller at 120 rpm gives 3.5 x 120 x 3.1416, or about 1,319 ft/min.
What is a good tip speed for mixing? It depends on the product: gentle blending of shear-sensitive fluids might target 500-1,000 ft/min, while high-shear dispersion can run several thousand. Match the tip speed that worked at lab scale.
Why hold tip speed constant during scale-up? Constant tip speed keeps the maximum shear rate near the blade roughly the same between vessels, which protects shear-sensitive products and reproduces dispersion quality from lab to plant.
What's the difference between tip speed and rpm? RPM is rotational speed of the shaft; tip speed is the linear velocity at the blade edge and depends on diameter too. A larger impeller at lower rpm can match a small one at high rpm.
When do I use the correction factor? Set it to 1 for a direct calculation. Use a value other than 1 only to apply a drive/gearbox ratio effect or a unit conversion; the default of 1 leaves the result unchanged at about 1,319 ft/min.

Last reviewed 2026-05-12.