Water line
Add water to just below or around the top of the rocks and media. Do not flood the barrel.
ROTARY TUMBLER WORKBENCH
Rock tumbler barrel fill and grit calculator
Estimate whether your barrel is underfilled, overfilled, or ready to run, then build a stage-aware grit, media, water, and timing plan.
Batch inputs
Use the visual fill you see in the barrel before starting the motor.
Customlb
BARREL STATUS
Target fill range
The barrel is in the usual 55-70% working range for a rotary tumbler.
Grit amount4 tbsp
60/90 or 80 grit silicon carbide
Weight fill estimate67%
Compare against your visual fill.
Stage timing7-10 days, then inspect shape and bruising
Media plan
Keep media nearby; a small top-up may help if the rocks slide or slap instead of rolling.
Stage checklist
- Remove mud and cracked pieces before recharge
- Keep the barrel in the 55-70% working range
QUICK GUIDE
How to use the rock tumbler calculator
1. Fill by volume first
Most rotary tumblers work best when the barrel is roughly 55-70% full after rocks and media are loaded. A half-empty barrel slaps; an overfull barrel may not roll.
2. Treat grit as an estimate
This planner uses tablespoon-per-pound estimates by stage. Your barrel maker, grit supplier, and rock type can override the number, especially for unusual loads.
3. Keep stages clean
Cross-contamination is one of the easiest ways to ruin a polish. Clean the barrel, lid, rocks, and media carefully before moving from coarse to finer stages.