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Why smoke alarms don't go off: 33 in 100 battery alarms stayed silent
When fire and rescue services in England attended house fires in 2025/26, they recorded 5,817 battery-powered smoke alarms and 14,273 mains-powered ones. 33.1 in every 100 battery alarms did not go off, against 20.9 in every 100 mains alarms. The most common reason by far was that the smoke never reached the alarm.
Reasons smoke alarms did not go off, per 100 alarms (2025/26)
The government publishes the reasons as a share of the alarms that failed. We have divided each reason by every alarm of that type recorded at house fires, so you can see how often each problem turns up across all alarms, battery and mains side by side.
| Reason | Battery (per 100) | Mains (per 100) |
|---|---|---|
| Smoke did not reach the alarm | 14.5 | 10.8 |
| Fire was in an area the alarms did not cover | 6.6 | 3.3 |
| Battery missing | 1.4 | 0.0 |
| Battery flat or faulty | 2.5 | 0.1 |
| Alarm removed or turned off | 0.5 | 0.7 |
| Fault or wrongly installed | 0.6 | 0.6 |
| Other or unknown (includes alarms damaged by the fire) | 7.0 | 5.4 |
| All reasons | 33.1 | 20.9 |
Smoke never reached the alarm: 21.0 in 100 battery alarms
Add together "smoke did not reach the alarm" and "fire was in an area the alarms did not cover" and you get 21.0 in every 100 battery alarms and 14.1 in every 100 mains alarms. In these cases the alarm itself may have been working: smoke from the fire did not reach it, or the fire was somewhere the alarms did not cover. Battery problems (missing, flat or faulty) came to 3.8 in 100 battery alarms.
That is why the government's Fire Kills campaign says to fit at least one smoke alarm on every level of your home, to consider alarms in the most used rooms including bedrooms, and a heat alarm in the kitchen. It also says to test smoke alarms at least monthly (Fire Kills: detect).
The trend since 2010/11
Missing batteries have almost disappeared as a reason, falling from 7.5 to 1.4 in 100 battery alarms. The overall share of battery alarms that did not go off has eased from 38.1 to 33.1 in 100, while mains alarms have stayed close to 21 in 100 (20.4 in 2010/11). Fewer battery alarms are being recorded at fires than in 2010/11 (5,817 against 10,792), and more mains ones.
| Year | Battery alarms | Battery: did not go off (per 100) | Battery: missing battery (per 100) | Mains alarms | Mains: did not go off (per 100) |
|---|---|---|---|---|---|
| 2010/11 | 10,792 | 38.1 | 7.5 | 12,617 | 20.4 |
| 2015/16 | 8,687 | 38.3 | 5.4 | 13,821 | 21.0 |
| 2020/21 | 6,650 | 38.5 | 3.0 | 13,569 | 22.6 |
| 2023/24 | 5,745 | 33.4 | 2.4 | 13,770 | 20.6 |
| 2024/25 | 5,555 | 32.9 | 1.6 | 13,834 | 20.9 |
| 2025/26 | 5,817 | 33.1 | 1.4 | 14,273 | 20.9 |
What this data can and cannot tell you
- It counts smoke alarms recorded by fire and rescue services at primary fires in dwellings in England that they attended. It is not a survey of alarms in all homes, and it does not cover Scotland, Wales or Northern Ireland.
- A house can have several alarms, and every alarm recorded is counted. The government's FIRE0702 table counts fires instead, so its figures differ.
- Battery and mains homes are not the same. These figures show what was found at fires, not how much safer one type makes a home.
- They say nothing about brands or models. "Other" includes alarms that were damaged by the fire and cases where the reason was not known.
- Fire records keep arriving after the data cut (12 May 2026), so later releases can revise these numbers slightly.
Buying alarms? See our guides to smoke alarms and carbon monoxide alarms. Download the full per-100 table for every year since 2010/11 (CSV).
Sources
- Ministry of Housing, Communities and Local Government, Fire statistics data tables FIRE0703 and FIRE0704: FIRE0703 (smoke alarm failures in dwelling fires by type of alarm) and FIRE0704 (reasons for failure), published 19 August 2026, data cut 12 May 2026. Accredited Official Statistics. Licensed under the Open Government Licence v3.0. The per-100 calculation is ours: reason counts from FIRE0704 divided by all recorded alarms of the same power type and year from FIRE0703.
- HM Government, Fire Kills campaign: smoke alarm advice.