Calculator Comparison

Electricity Cost Calculator vs Water Heater Size Calculator

Not sure which calculator to use? Here's a side-by-side comparison of the Electricity Cost Calculator and Water Heater Size Calculator to help you pick the right one for your needs.

Electricity Cost Calculator

Home & Real Estate

Calculate the cost of running any electrical device based on its wattage, daily usage hours, and your electricity rate.

What you enter

Wattage
Hours Used Per Day
Electricity Rate
Days Per Month

What you get

Monthly Cost(primary)
Daily Cost
Annual Cost
Monthly kWh Usage

Use Electricity Cost Calculator

Water Heater Size Calculator

Home & Real Estate

Calculate the right water heater size for your household based on family size, usage habits, and peak hot water demand for both tank and tankless systems.

What you enter

Number of People
Number of Bathrooms
Hot Water Usage

What you get

Recommended Tank Size (gallons)(primary)
Tankless Flow Rate (GPM)
Peak Hour Demand (gallons)

Use Water Heater Size Calculator

Key Differences

Feature	Electricity Cost Calculator	Water Heater Size Calculator
Category	Home & Real Estate	Home & Real Estate
Inputs	4 required fields	3 required fields
Outputs	4 results	3 results
Chart	No chart	No chart
FAQs	3 answered	3 answered

Input Comparison

Only in Electricity Cost Calculator

Wattage
Hours Used Per Day
Electricity Rate
Days Per Month

Only in Water Heater Size Calculator

Number of People
Number of Bathrooms
Hot Water Usage

Which Calculator Should You Use?

Use the Electricity Cost Calculator if you need to:

Calculate monthly cost
When you know your wattage and hours used per day

Use the Water Heater Size Calculator if you need to:

Calculate recommended tank size (gallons)
When you know your number of people and number of bathrooms

Frequently Asked Questions

How do I calculate electricity cost for an appliance?

Multiply the appliance wattage by hours of use per day, divide by 1,000 to get kWh, then multiply by your electricity rate. For example, a 1,000W space heater running 8 hours at $0.12/kWh costs $0.96 per day or about $28.80 per month.

What is the average electricity rate in the US?

The average US residential electricity rate is approximately $0.12 to $0.16 per kWh as of 2025. Rates vary significantly by state, from $0.08/kWh in some southern states to over $0.30/kWh in Hawaii and parts of New England.

What size water heater do I need?

For a family of 4 with average usage: 50-gallon tank or 7-8 GPM tankless. 1-2 people need 30-40 gallons, 3-4 need 40-50, and 5+ need 50-80 gallons.

Tank vs tankless water heater?

Tank heaters cost less upfront ($800-$1,500) but use more energy. Tankless heaters cost more ($1,000-$3,500) but are 24-34% more energy efficient and last longer (20+ years vs 10-15).

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Bottom Line

Choose the Electricity Cost Calculator if you need to calculate monthly cost. Use the Water Heater Size Calculator if you need to calculate recommended tank size (gallons). Both calculators are free and require no sign-up.

Use Electricity Cost Calculator Use Water Heater Size Calculator

Feature

Electricity Cost Calculator

Water Heater Size Calculator