Practical research · 21 September 2026
Rock Tumbler Electricity Cost Calculator and Worked Example
Rock tumbler electricity cost depends on power draw, running time and the electricity rate you pay. The calculator below uses your own values and reports energy in kilowatt-hours. It does not include grit, polish, water, equipment wear or fixed charges on your bill.
Estimate your tumbler’s electricity cost
Starting values are the illustrative example below. Replace them with your own measurements and tariff.
Estimated energy: 26.88 kWh. Variable cost: 6.72 currency units.
Use 0.25 for 25 cents per kWh. No currency conversion is performed. Fixed charges and consumables are excluded. Entries stay in this page and are not saved.
Use the power figure you actually have
Measured average power over a representative run is more useful than an unrelated motor or output rating. If you use the machine’s stated input wattage, treat the result as an estimate and record that assumption. Follow the instructions for any suitable energy monitor and electrical equipment you use.
The basic calculation is watts divided by 1,000, multiplied by running hours. Multiply that kWh figure by your variable electricity price per kWh. Enter the tariff in whole currency units, such as 0.25 for 25 cents, rather than entering 25.
Source: Government of South Australia: appliance running-cost calculation
A transparent worked example
An illustrative 40 W average draw running continuously for 28 days uses 26.88 kWh: 40 ÷ 1,000 × 24 × 28. At an illustrative tariff of 0.25 per kWh, the variable energy cost is 6.72 in that currency. These are assumed inputs, not measured specifications of a particular tumbler.
If the same machine runs 12 hours per day for 28 days, the estimate halves to 13.44 kWh and 3.36 at the same tariff. Use actual powered hours; do not count a stopped barrel as though its motor were running.
| Input | Illustrative value |
|---|---|
| Average input power | 40 W |
| Operating time | 24 hours/day × 28 days = 672 hours |
| Energy | 26.88 kWh |
| Tariff | 0.25 currency units/kWh |
| Variable energy cost | 6.72 currency units |
Understand what the estimate leaves out
A time-of-use tariff needs separate calculations for hours charged at different rates. Add those results to estimate the total variable charge. Fixed daily supply charges are not caused solely by running the tumbler and are excluded here.
Total batch cost also includes consumables and equipment ownership. Keep those separate so a change in energy price does not obscure a change in grit use or rejected batches. Cost per successful batch can be more useful than cost per calendar week.
Make the comparison fair
Use the same batch objective and operating period when comparing machines. A lower wattage is not automatically cheaper per finished batch if the process takes longer or carries less material. We have not measured comparative polishing efficiency.
Save your inputs with the batch record. Recalculate when the run schedule or tariff changes, and label a nameplate-based estimate as such. The calculator is a planning tool, not a prediction of the full electricity bill.