Start with energy per complete cycle
For the cleanest estimate, use a cumulative kWh reading from the moment the countertop dishwasher starts until the cycle is fully finished. That total captures changes between pumping, internal water heating, washing and drying. One instantaneous watt reading cannot describe the whole cycle.
If the appliance documentation gives annual kWh rather than energy per cycle, keep the label assumptions visible. ENERGY STAR explains that dishwasher annual calculations use 215 cycles per year under the federal test procedure. Dividing annual kWh by 215 creates a test-based per-cycle comparison, not a promise for every selected program.
Calculate one load and a month
The basic calculation is energy per cycle × electricity rate. In an illustrative case, 1.0 kWh × $0.18/kWh equals $0.18 per cycle. Five cycles each week for four weeks would use 20 kWh and cost $3.60. Use the actual number of cycles rather than assuming that a small household always runs the machine daily.
| Energy per cycle | Cycles per month | Monthly energy | Cost at $0.18/kWh |
|---|---|---|---|
| 0.6 kWh | 12 | 7.2 kWh | $1.30 |
| 1.0 kWh | 20 | 20.0 kWh | $3.60 |
| 1.3 kWh | 30 | 39.0 kWh | $7.02 |
The rows are sensitivity examples, not typical-model claims. Cycle selection, incoming-water temperature, soil sensing and heated drying can change the result.
Compare compact capacity, not only one cycle
ENERGY STAR defines compact dishwashers by place-setting capacity and publishes separate energy and water criteria. A lower cost per cycle does not necessarily mean a lower cost per dish if the smaller machine must run more often. Record place settings, useful rack layout and realistic load frequency beside the energy figure.
A countertop or portable installation also needs a suitable faucet connection, drainage arrangement, counter clearance and electrical supply. Verify the exact manual and lease rules before buying. A low operating-cost estimate does not make an unsuitable installation safe or permitted.
Keep the comparison auditable
Create one row per candidate with the full model number, capacity, annual kWh, test-cycle basis, water use, drying method and purchase price. If the listing and EnergyGuide label disagree, use the exact-model documentation rather than averaging the two figures.
After purchase, measure several cycles you genuinely use. Compare normal, quick and heated-dry settings only with similar loads and note whether hot water is supplied by the machine or the building. This produces a practical monthly range and prevents a single convenient cycle from becoming an unsupported annual claim.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.