Hot water can account for much more of a washer’s operating energy than the motor, and a dishwasher also uses energy to heat water and dry dishes. ENERGY STAR attributes about 90% of clothes-washer operating energy to water heating, but that general guidance is not a fixed percentage for every machine or cycle. To estimate your cost, separate the electricity used inside the appliance from the energy used by the household water heater—and identify whether that heater runs on electricity or gas.
Washer and Dishwasher Energy Cost by Cycle
The following is a hypothetical U.S. household example, not measured appliance performance or an official benchmark. It assumes electric resistance water heating, electricity at USD 0.20/kWh, incoming water at 60°F, and five cycles per week for each appliance. The assigned appliance-energy values and heated-water volumes illustrate the calculation; replace them with your model’s documentation or measured inputs.
| Appliance and setting | Assumed appliance electricity per cycle¹ | Water volume heated above 60°F² | Calculated total electricity per cycle | Energy cost per cycle | Annual energy cost at 260 cycles |
|---|---|---|---|---|---|
| Washer: cold, with no added heat | 0.10 kWh | None | 0.100 kWh | USD 0.020 | USD 5.20 |
| Washer: warm | 0.10 kWh | 5 U.S. gal to 90°F | 0.466 kWh | USD 0.093 | USD 24.23 |
| Washer: hot | 0.10 kWh | 5 U.S. gal to 120°F | 0.832 kWh | USD 0.166 | USD 43.26 |
| Dishwasher: assumed hot-water cycle | 0.70 kWh | 3 U.S. gal to 120°F | 1.139 kWh | USD 0.228 | USD 59.24 |
¹ Appliance electricity includes motors, pumps, controls, and any internal heating or powered drying. It excludes the household water heater.
² Heated-water volume is not necessarily total cycle water use. Cold rinses do not belong in the hot-water calculation. For the warm-wash example, the volume represents five gallons of mixed wash water raised from 60°F to 90°F.
In this example, running the hot-wash setting and the dishwasher five times each week costs USD 102.50 per year in energy. Changing only the washer to an unheated cold cycle reduces that total to USD 64.44, saving USD 38.06 annually. These totals exclude water and sewer charges, detergent, clothes drying, standby energy, and water-heater storage and distribution losses.
The dishwasher row is not a recommendation to change its water connection or inlet temperature. Follow the appliance’s installation instructions: GE’s published guidance, for example, requires hot-water supply between 120°F and 150°F for the dishwashers covered by that guidance.
Why Hot Water Can Cost More Than the Motor
A motor’s wattage does not tell you the appliance’s complete operating cost. Energy depends on both power and operating time:
[
E_{\text{electric}}(\text{kWh})
=
P(\text{kW})\times t(\text{hours})
]
For a cycling load, add the energy consumed during each operating period rather than multiplying maximum nameplate power by the entire cycle duration. An appliance that draws more power briefly can use less energy than one drawing less power for a longer period.
There is also a measurement boundary to consider. A washer supplied with household hot water can draw relatively little electricity at its receptacle while causing additional consumption at the water heater. A dishwasher can use both externally heated water and electricity for its internal booster heater and drying system. ENERGY STAR explicitly includes machine operation, water heating, and drying in its explanation of dishwasher energy use.
Cold washing reduces the water-heating component, not necessarily every component of the cycle. ENERGY STAR recommends cold washing for most ordinary laundry, while noting exceptions such as oily stains and some illness-related circumstances. Follow fabric-care instructions and the washer’s guidance when choosing a temperature.
Official Reference Values and Their Limits
These U.S. references were checked for this 2026 update. Their underlying specification and data dates remain important; a 2023 specification does not become a “2026 standard” simply because it is still published.
| Official reference | Published value or condition | How to use it |
|---|---|---|
| ENERGY STAR clothes-washer guidance | About 90% of operating energy attributed to water heating | General guidance explaining why wash temperature matters—not a model-specific energy split. |
| ENERGY STAR standard-size dishwasher criteria | No more than 240 kWh/year and 3.2 U.S. gal/cycle; criteria effective July 19, 2023 | Certification thresholds, not the consumption of every certified model or selected cycle. |
| ENERGY STAR dishwasher annual test basis | 215 cycles/year | A standardized comparison basis; five cycles per week equals 260 cycles/year. |
| DOE residential dishwasher purchasing analysis | Annual energy includes hot water supplied by an electric resistance water heater | Establishes why the published annual figure cannot automatically be treated as receptacle-only electricity. Analysis updated October 2023. |
| EIA U.S. residential electricity data | USD 0.1831/kWh for July 2026, released September 24, 2026 | A national reference starting point, not your local tariff or a full-year 2026 average. |
Use the specific model’s EnergyGuide label and manufacturer documents when comparing appliances. The FTC explains that EnergyGuide operating costs use standardized usage and national energy-price assumptions; actual costs depend on your usage and local energy price.
Your utility’s current residential rate schedule and bill are the appropriate sources for the electricity price in your calculation. The hypothetical USD 0.20/kWh used here is deliberately separate from EIA’s July 2026 national figure.
Calculate Water-Heating Energy by Hand
Establish the Inputs
For a water-heating calculation, record:
- The volume actually heated, in U.S. gallons.
- Incoming cold-water temperature, in °F.
- The temperature reached by that water, in °F.
- Appliance electricity per cycle, in kWh.
- Water-heater type and the efficiency assumption used.
- Electricity price in USD/kWh and, where applicable, gas price in USD/therm.
- Cycles per week.
Do not substitute the appliance’s total water consumption for heated-water volume unless all that water is actually heated. Likewise, separate externally heated water from internal booster heating so the same heat is not counted twice.
Use the Heat Formula
An approximate water-heating relationship is:
[
Q_{\text{water}}(\text{Btu})
=
8.33\times V\times(T_{\text{target}}-T_{\text{incoming}})
]
Here, (V) is U.S. gallons, and temperature rise is in °F. The factor 8.33 reflects the approximate pounds of water per U.S. gallon, with approximately one Btu required to raise one pound of water by 1°F.
Using 3,412 Btu per kWh:
[
Q_{\text{water}}(\text{kWh thermal})
=
\frac{8.33\times V\times\Delta T}{3,412}
\approx
0.00244\times V\times\Delta T
]
EIA publishes the 3,412 Btu/kWh conversion. The examples below use the rounded coefficient 0.00244 consistently.
Thermal kWh describes heat delivered to the water. It is not automatically the electricity purchased from the utility.
Work Through the Hot-Wash Example
For the first table’s hypothetical hot wash:
1. Calculate temperature rise:
[
\Delta T=120-60=60^\circ\text{F}
]
2. Calculate heat delivered to five gallons:
[
Q_{\text{water}}
=
0.00244\times5\times60
=
0.732\text{ kWh thermal}
]
- Assume idealized resistance heating with conversion efficiency (\eta=1.00), excluding storage and piping losses:
[
E_{\text{water heater}}
=
\frac{0.732}{1.00}
=
0.732\text{ kWh}
]
4. Add the assigned washer electricity:
[
E_{\text{total}}
=
0.732+0.100
=
0.832\text{ kWh/cycle}
]
5. Multiply by the assumed rate and annual cycle count:
[
C_{\text{annual}}
=
0.832\times0.20\times(5\times52)
=
\text{USD }43.264
]
Rounded annual energy cost is USD 43.26. This is a transparent estimate for the stated inputs—not a measured bill or a guarantee of performance.
Annual Cost at Five Washer and Five Dishwasher Cycles per Week
Both appliances run:
[
5\times52=260\text{ cycles/year each}
]
For the dishwasher, the hypothetical external water-heating requirement is:
[
Q_{\text{dishwasher water}}
=
0.00244\times3\times(120-60)
=
0.4392\text{ kWh thermal/cycle}
]
Adding the assumed 0.70 kWh of dishwasher electricity:
[
C_{\text{dishwasher}}
=
(0.4392+0.70)\times260\times0.20
=
\text{USD }59.2384
]
The annual comparison is:
| Hypothetical household operating pattern | Washer energy cost | Dishwasher energy cost | Combined annual energy cost |
|---|---|---|---|
| Hot washer cycle + dishwasher | USD 43.26 | USD 59.24 | USD 102.50 |
| Warm washer cycle + dishwasher | USD 24.23 | USD 59.24 | USD 83.47 |
| Unheated cold washer cycle + dishwasher | USD 5.20 | USD 59.24 | USD 64.44 |
The warm-wash calculation uses a 30°F rise:
[
E_{\text{warm washer}}
=
0.10+(0.00244\times5\times30)
=
0.466\text{ kWh/cycle}
]
Actual savings depend on the hot-water volume, incoming temperature, appliance behavior, and water-heating system. ENERGY STAR’s broad temperature-setting guidance explains the opportunity, but the table’s dollar savings come only from the explicitly assigned example inputs.
Electric Resistance, Gas, and Heat Pump Water Heating
Changing the household water heater changes how you price externally supplied hot water. It does not remove the appliance’s own electricity consumption.
| Household water-heating system | External water-heating calculation | Important boundary |
|---|---|---|
| Electric resistance | Electrical kWh = thermal kWh ÷ assumed conversion efficiency | Storage and distribution losses must be handled separately if excluded from the efficiency assumption. |
| Natural gas | Therms = required Btu ÷ (100,000 × assumed thermal efficiency) | Price the gas separately; internal appliance heaters and powered drying remain electrical loads. |
| Heat pump | Electrical kWh = thermal kWh ÷ operating COP | Use an operating coefficient of performance appropriate to the conditions; backup resistance heating can change consumption. |
For gas heating:
[
C_{\text{cycle}}
=
E_{\text{appliance}}\times r_e
+
\frac{8.33\times V\times\Delta T}
{100{,}000\times\eta_g}
\times r_g
]
Here, (r_e) is USD/kWh, (r_g) is USD/therm, and (\eta_g) is the assumed gas-to-water thermal efficiency. One therm equals 100,000 Btu.
For a heat pump, COP expresses heat delivered divided by electricity consumed under the operating conditions. Do not assume every hot-water draw achieves the same COP, especially when the unit uses resistance backup. DOE’s guidance distinguishes heat-pump-only operation from operation involving resistance elements.
These simplified calculations estimate the energy associated with a draw. Do not casually substitute a water heater’s annual rating for a marginal per-cycle efficiency. If you allocate tank standby losses, recirculation energy, or piping losses to appliance use, state the allocation method rather than silently adding the water heater’s entire household consumption.
Common Cost-Calculation Pitfalls
Avoid double-counting hot-water energy. A dishwasher’s published annual energy figure may already include household water heating: DOE’s purchasing analysis explicitly uses electric-resistance hot-water supply. Either start with a documented whole-system estimate or build the estimate from separate appliance and water-heater components—not both.
Treating Every “Cold” Setting as Zero Heating
Cold-water conditions vary with the incoming supply. GE notes that incoming cold-water temperature can vary substantially by season and location. Check the model’s temperature-control description before treating a selected setting as completely unheated.
The cold row in this article specifically assumes no household hot-water draw and no internal water heating. It is an example condition, not a claim about every washer.
Applying Washer Advice to a Dishwasher
Cold washing is a laundry option, not permission to supply a hot-water-connected dishwasher with cold water. GE’s dishwasher guidance requires the specified hot-water connection and inlet temperature.
Where the dishwasher permits it, selecting air drying can reduce the electrical drying component. DOE recommends air drying as an energy-saving option, but the savings must be determined for the model and cycle rather than assigned a universal percentage.
Using the Wrong Electricity Price
For a flat-rate savings estimate, use the avoidable per-kWh charges from your utility tariff, including applicable volumetric delivery charges and adjustments. A fixed monthly customer charge generally does not disappear when you run fewer cycles.
Under time-of-use billing, price consumption during the relevant periods. If a residential appliance is used in a facility on a commercial tariff, a kWh-only estimate is not a complete bill forecast when demand charges also apply. The appliance’s presence alone does not establish its contribution to the facility’s billed peak.
Confusing Appliance Cost With Complete Household Cost
The calculations here cover operating energy only. Water and sewer charges require separate local inputs:
[
C_{\text{water and sewer}}
=
\frac{V_{\text{total cycle}}}{1{,}000}
\times r_{\text{water and sewer}}
]
This form applies when the combined volumetric rate is quoted in USD per 1,000 gallons. Use total billed water volume—not just heated-water volume—and follow the utility’s actual sewer billing method.
For the appliance-electricity portion, the site’s appliance-cost calculator provides a calculation entry point; keep external water heating separate unless it is explicitly included in your inputs.
Washer and Dishwasher Cost-Check Checklist
Use this checklist before comparing settings, estimating annual savings, or interpreting an EnergyGuide figure:
- Identify the exact appliance model and selected cycle.
- Confirm whether the starting energy figure includes household water heating.
- Separate appliance electricity from externally supplied hot-water energy.
- Distinguish total water use from the volume actually heated.
- Record incoming temperature, target temperature, and temperature rise.
- Identify electric resistance, gas, or heat pump water heating.
- Use the current local tariff, with energy units matched to the bill.
- Use your actual weekly cycle count rather than the label’s standardized usage.
- State whether standby, storage, piping, water, sewer, and drying costs are included.
- Preserve required wash temperatures and manufacturer-specified dishwasher supply conditions.
These calculations support operating-cost decisions. They do not establish electrical service demand, circuit sizing, NEC compliance, permit approval, or appliance suitability, and they do not replace manufacturer instructions, local AHJ requirements, or qualified on-site judgment.