WattMath

Space Heater vs Central Heat Calculator

Calculate which heating method costs less for your situation—portable space heaters or central heating with gas, propane, or oil.

Space Heater Details

Central Heating Details

Zone Heating Context

Room you're heating with space heater

Zone Heating

Space heaters can save money when heating only occupied rooms. They're 100% efficient at converting electricity to heat, but electricity often costs more than gas per BTU.

  • 1500W heater: ~5,100 BTU/hour
  • Best for: small rooms, occasional use
  • Central heat wins for whole-home heating

How to Use

  1. Enter your space heater details and electricity rate
  2. Enter your furnace efficiency and fuel costs
  3. Click Calculate to compare monthly costs

FAQ

When are space heaters more cost-effective?

Space heaters can save money when you're heating only one room for a few hours, your electricity is cheap, or your fuel prices are very high. They rarely beat central heat for whole-home heating.

Are space heaters safe?

Modern space heaters with tip-over protection and overheat shutoff are safe when used properly. Keep them away from flammables, never leave unattended, and don't use extension cords.

What size heater do I need?

As a rule of thumb, you need about 10 watts per square foot. A 1500W heater can comfortably heat a 150 sq ft room. For larger spaces, you may need multiple heaters.