Process tool
Coating spray rate calculator
Spray rate per gun and total run time from your dispersion quantity and available process window.
- Runs in the browserNothing is submitted anywhere
- Working shownCheck every line by hand
- Plant figuresThe bands our grades run in
- Free, no sign-inNo account, no email
Written by the Rglax Pharma technical team, who formulate and manufacture every grade named on this calculator at our WHO-GMP works in Tahliwal, Una (drug manufacturing licence NNZ/23/238). Reviewed 3 September 2026. Licences and certificates.
Result
Total spray rate
85.8 g/min
- Per gun
- 28.6 g/min
- Per gun per hour
- 1.72 kg/h
- Run time
- 2 h
How this was worked out
- total rate = 10.3 kg × 1000 ÷ 120 min = 85.8 g/min
- per gun = 85.8 ÷ 3 guns = 28.6 g/min
Formula
spray rate (g/min) = dispersion (g) ÷ spray time (min) per gun = total ÷ number of guns
Why this number matters
Spray rate is the parameter you adjust when something goes wrong. Too fast and the bed over-wets, which shows as picking, sticking and twinning. Too slow and the droplets dry before they land, which shows as orange peel and a dull, rough film. The number here is a starting point; the bed tells you whether it is right.
Where it goes wrong
Ramp up rather than starting at the calculated rate. Begin around 70 percent of it, watch the bed for two or three minutes, and increase once you are satisfied the tablets are tacky rather than wet.
Worked example
With total dispersion of 10.3 kg, spray time of 120 min and number of guns of 3, the calculation gives:
- Total spray rate
- 85.8 g/min
- Per gun
- 28.6 g/min
- Per gun per hour
- 1.72 kg/h
- Run time
- 2 h
The arithmetic is 2 lines, shown beside the result above so it can be checked by hand: spray rate (g/min) = dispersion (g) ÷ spray time (min); per gun = total ÷ number of guns.
Typical ranges
- Spray time(min)Excludes warm-up and drying
These are the bands our grades were developed in at Tahliwal. A run outside them is not wrong, but it is a run the published parameters no longer describe.
Other calculators
- Coating weight gainHow much dry coating material a batch needs at a target percentage weight gain, including process loss.
- Coating dispersionWater or solvent needed to disperse a ready-mix powder at a given solids concentration.
- Pan speedTangential bed velocity from pan diameter and RPM, with the range most film coating runs sit in.
- Drying capacityHow much water your inlet air can actually carry away, and the spray rate that supports.
- Dispersion vesselVessel volume, diameter and impeller size for the dispersion quantity you are making.
- Surface area and build-upSurface area per tablet and coating build-up in mg per square centimetre, which is how enteric coats are specified.
Every grade page carries the process parameters it was developed on, so you can start from a known point rather than a calculated one. Browse the grades.
Read next
- Film coating systemRate is bounded by what the bed can dry, and that is a property of the system, not the pump.
- Orange peel and pickingThe two defects that follow directly from spraying faster than the bed can take it.
- Tablet coating weight gain calculatorHow much dry coating material a batch needs at a target percentage weight gain, including process loss.
- Coating dispersion and solids calculatorWater or solvent needed to disperse a ready-mix powder at a given solids concentration.
- Coating pan speed and tangential velocity calculatorTangential bed velocity from pan diameter and RPM, with the range most film coating runs sit in.
Need a second opinion
Talk to our technical team.
Send the core, the coater and the target and we will tell you what we would run, and which grade we would run it with.
From the calculation to the pan.