Model
Danby DDW631SDB
Rank #11 means 10 of the 709 dishwasher models we track cost less to run each year; the 13th efficiency percentile means it uses less energy for its size than 13% of those models.
What does the Danby DDW631SDB cost to run per year?
Do the math and the Danby DDW631SDB's $29/yr running cost puts it at rank #11 of 709, among the least expensive dishwasher models we track to keep running. It uses 30.2% less energy than the U.S. federal standard model in its class, which would cost about $41/yr to run, a saving of roughly $12 a year. Size-adjusted, this model ranks near the bottom of its class on efficiency, ahead of just 13% of dishwasher models we track. This class has no published efficiency-factor figure beyond annual kWh itself, so at 6 place settings (the class spans 2 to 18), size is the clearest lever we can point to for this model's running cost.
Immediately around it on the leaderboard, the Danby DDW621WDB at $29/yr runs a little cheaper and the Edgestar DWP63** at $29/yr runs a little more, a sense of how tightly models are packed at this point in the ranking. A dishwasher typically stays in service for somewhere around 9 years; over that span, the Danby DDW631SDB's $29/yr adds up to roughly $261 in electricity alone, before purchase price or repairs.
Also sold as: Black+Decker BCD6W.
By the numbers
The Danby DDW631SDB normalized against its whole class, so each figure means something.
What it costs you over time
Running cost is an every-year number, so it compounds. At $29/yr, here is what the Danby DDW631SDB adds up to before purchase price, water, or repairs enter the math.
Left running for a decade at today's US average rate, the Danby DDW631SDB costs about $290. That is roughly $120 less than a standard model in its class, which would run closer to $410 over the same ten years.
How the Danby DDW631SDB compares
The dishwasher class we track runs from $15 to $45 a year. At $29/yr, it runs about $15 a year cheaper than the class median of $44, and it is about $14 a year more than the cheapest dishwasher to run at $15. Against the US federal standard model for its class at about $41/yr, the Danby DDW631SDB uses 30.2% less energy.
What drives its running cost
At 6 place settings, the Danby DDW631SDB is a small dishwasher for its class, which spans 2 to 18 place settings with a median of 14 place settings, less capacity to service is usually the first reason a running-cost figure lands on the low side, before efficiency even enters the picture.
- Place-setting capacity. Place-setting capacity is the main driver of how much water a cycle has to heat, and heating that water is most of a dishwasher's electricity use.
- Water heating. Most dishwashers have a booster heater that raises incoming water to sanitizing temperature; this heating step, not the pump or motor, accounts for most of a cycle's electricity use.
- Cycle length and drying method. Heavy or sanitize cycles run longer and hotter than a normal or eco cycle, and heated-dry options cost more to run than air-dry or condensation drying.
Common questions
Is the Danby DDW631SDB cheap to run?
Yes. Its $29/yr running cost puts it at rank #11 of 709, below what most dishwasher models we track cost to run.
How much does the Danby DDW631SDB cost per month?
About $2.4 a month, which is the $29 annual estimate spread across twelve months at the US average rate of $0.1856/kWh. Your own bill scales with your local electricity rate and how heavily you use it.
How is this running-cost figure calculated?
The formula is annual kWh times price per kWh: 155 kWh from ENERGY STAR times the US average of $0.1856/kWh comes to about $29 a year. It covers electricity only, not the purchase price, water, or installation.
How efficient is the Danby DDW631SDB for its size?
13th percentile once size is factored in. That means its size-adjusted efficiency is not the main reason for the running-cost figure above; its capacity plays a large role too.
Cheaper to run in the same class
Source
ES_0092264_DDW631SDB_05292023110806_80164647View certified dishwasher listingsENERGY STAR data as of July 2026Danby and DDW631SDB are used here for identification only and are not endorsements. Figures are computed by WattWise Labs from public ENERGY STAR data, not measured in our own lab.