Space heater fire statistics, with sources attached

Why the sourcing on this page is laboured

Space heater fire statistics are among the most frequently mis-cited numbers on the consumer web. Percentages get lifted from one article to the next without a year attached, and the underlying figures change between report editions — so a share that was accurate a decade ago keeps circulating long after the data behind it moved.

Every number on this page is therefore stated with the report it came from, the years it covers and the date it was published. Where a figure is our arithmetic rather than a published statistic, we say so and show the division. And where we could not verify something, it simply is not here — there is a note at the bottom about exactly what we left out and why.

All residential heating fires

From the U.S. Fire Administration's Heating Fires in Residential Buildings (2017–2019), Topical Fire Report Series Volume 21 Issue 10, published December 2021, drawn from the National Fire Incident Reporting System:

The report also records that heating remains the second leading cause of residential building fires, and that it declined substantially from its peak in the late 1970s and early 1980s.

Portable heaters specifically

The USFA publishes a separate report on portable heaters — Portable Heater Fires in Residential Buildings (2017–2019), Volume 21 Issue 11, also December 2021. Its findings section reads: *“Each year, from 2017 to 2019, an estimated average of 1,100 portable heater [fires in residential buildings] ... caused an estimated annual average of 65 deaths, 150 injuries and $51 million in property loss.”*

What causes them

The heating-fires report identifies misuse of material or product as the leading factor contributing to ignition, at 34% — a category the report explicitly describes as including a heat source placed too close to combustibles. The portable heater report names the same two behaviors: heaters too close to combustible items, and heaters left unattended.

The heating-fires report also gives the areas of origin for residential heating fires:

Bedrooms and living rooms together account for over 18% — which is where portable heaters live, and which is why the overnight question is the one that matters most.

One more figure worth knowing

The same report records that smoke alarms were present in 54% of nonconfined residential heating fires, with none present in 24% and the status undetermined in the remainder. That is the cheapest gap on this page to close, and it is not a heater purchase.

What to do with all of this

1. 1.Three feet of clearance in every direction — the USFA's own rule, and the one that addresses the leading contributing factor directly.
2. 2.Turn it off when you leave the room or go to bed — the second USFA rule, and the one that addresses the unattended factor. How to do that and still be warm.
3. 3.Plug it directly into the wall. Why extension cords are the wrong tool.
4. 4.Check the smoke alarm. More than a fifth of these fires happened in homes with no alarm present.
5. 5.Buy a unit with a published tip-over cutoff. What each safety feature prevents.

What we left out, and why

Both USFA reports include charts of fires by month and by time of day. The published figures in those charts could not be matched to their axis labels with confidence from the source document, so they are not reproduced here — a plausible-looking monthly distribution with the months in the wrong order would be worse than no distribution at all.

We also do not cite the widely circulated NFPA figures that appear in most articles on this subject. NFPA's own report page returns no extractable content, so those numbers reach the web through secondary reporting, and at least one commonly quoted percentage comes from a superseded edition. Where we cannot read the primary document, we do not quote it.