Best First Alert Smoke Detector 2026

First Alert Invented the Residential Smoke Alarm — Here Are the 12 Models That Still Earn Their Place on Your Ceiling

Reviewed by the WC Safety Editorial — independent safety specialists. Last updated: August 16, 2026.

Looking for the full lineup? See our best smoke detectors of 2026 roundup for our top overall picks across every type.

Short answer: First Alert’s catalogue has rolled over — every alarm this guide used to rank is discontinued, replaced by the current Precision Detection line. The SM300-AC is the pick for most homes: a dual-sensor hardwired alarm with battery backup, and First Alert’s own successor to the long-running 3120B. On battery power, the SM210 pairs photoelectric sensing with a sealed 10-year cell, and the SC5 is the smart smoke-and-CO alarm Google names as the Nest Protect replacement. Every discontinued model and its named successor is in the legacy table at the foot of the page.

The Brand Behind the Industry: BRK Brands — the parent company of First Alert — manufactured the first residential smoke alarm sold to American consumers in 1969. More than five decades later, the company produces more residential smoke detection devices than any other manufacturer in North America. That scale doesn't guarantee that every First Alert model is the right choice for every application — but it does mean the underlying sensing technology has been tested in more real-world fire events than any competitor's product.

Quick Comparison — 8 Current First Alert Alarms

Prices are approximate Amazon street prices as of May 2026. Ratings reflect aggregated user review data and editorial assessment.

1. First Alert SM300-AC — Best Overall First Alert Alarm

The SM300-AC is First Alert’s designated successor to the 3120B that led this page for years, and it keeps the reason the 3120B mattered: a genuine dual-sensor head, so one model covers both smouldering and fast-flaming fires across a whole hardwired chain. 120V power, two AA backup cells, and interconnection with up to 18 First Alert/BRK devices (max 12 smoke alarms).

Specs: Dual sensor (photoelectric + ionization) | 120V AC + 2x AA backup | Interconnect up to 18 devices | 85 dB | End-of-life signal | UL 217

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2. First Alert SM210 — Best Battery First Alert Alarm

The SM210 is the current battery pick: photoelectric sensing with First Alert’s Precision Detection tuning against cooking nuisance, on a sealed 10-year lithium cell in a slim housing. Nothing to wire, nothing to replace, no low-battery chirp for a decade. It is also the named replacement for the discontinued P1210.

Specs: Photoelectric | Sealed 10-year lithium | 85 dB | Test/silence | End-of-life signal | UL 217

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3. First Alert SC5 (Battery) — Best Smart First Alert Alarm

The SC5 is the alarm Google chose: when Nest Protect was discontinued in March 2025, Google partnered with First Alert and named the SC5 as the replacement. It runs in the Google Home app alongside existing Nest units, sends phone alerts, and announces the hazard type and location by voice. The battery model is SMCO600NV; the hardwired FSMCO600NVACCL1 is a separate SKU we have not verified on Amazon, so the link below is the battery version specifically.

Specs: Smoke + carbon monoxide | Battery (SMCO600NV) | Google Home | Voice alerts with location | 85 dB | UL 217 9th Edition + UL 2034

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4. First Alert SMICO100-AC — Best Hardwired Smoke + CO Combo

The SMICO100-AC is the current hardwired combination unit — smoke and carbon monoxide in one interconnected head with battery backup — and First Alert’s named replacement for the discontinued SC9120B. The practical detail that matters for retrofits: it ships with an adapter plug so it can replace an existing hardwired alarm without rewiring the harness.

Specs: Smoke + carbon monoxide (Precision Detection) | 120V AC + battery backup | Interconnect | Adapter plug included | 85 dB | UL 217 + UL 2034

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5. First Alert SM310 — Best Dual-Sensor Sealed-Battery Alarm

The SM310 puts both sensing technologies on a sealed 10-year battery — the most fire-coverage per device in the battery line, and the named replacement for the discontinued SA3210. First Alert currently shows it as backordered, which is a stock note, not a lifecycle one.

No affiliate link. We could not verify an Amazon listing whose title names this exact model, so we link nothing rather than the wrong product — check First Alert’s own catalogue.

Specs: Dual sensor | Sealed 10-year lithium, non-replaceable | 85 dB | End-of-life timer | UL 217

6. First Alert SM500V — Best Wireless-Interconnect Battery Alarm

The SM500V is the battery route to whole-home interconnection: it links wirelessly with up to 12 other First Alert/BRK alarms plus 6 compatible devices over roughly 100 feet, and its voice alert names which of 11 programmable rooms is alarming. The trade-off is two replaceable AA cells rather than a sealed pack. It replaces the discontinued SA511.

No affiliate link. We could not verify an Amazon listing whose title names this exact model, so we link nothing rather than the wrong product — check First Alert’s own catalogue.

Specs: Photoelectric | 2x replaceable AA | Wireless interconnect (12 alarms + 6 devices) | Voice location | 85 dB | UL 217

7. First Alert SMCO100 — Best Battery Smoke + CO Combo

The SMCO100 is the non-smart battery combination unit: both hazards in one device with Precision Detection sensing, no wiring, no app. It replaces the discontinued SCO5CN.

Specs: Smoke + carbon monoxide (Precision Detection) | Battery | 85 dB | Test/silence | UL 217 + UL 2034

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8. First Alert SMI100-AC — Best Budget Hardwired Alarm

The SMI100-AC is the budget way to keep a hardwired chain current: ionization sensing with Precision Detection tuning, 120V power with 9V backup, interconnection, and no rewiring to replace an existing detector. It is the named replacement for the discontinued 9120B. First Alert currently shows it as backordered; the Amazon listing is live.

Being ionization, keep it away from kitchens — at least 10 feet from cooking appliances — and prefer the dual-sensor SM300-AC where the budget allows.

Specs: Ionization (Precision Detection) | 120V AC + 9V backup | Interconnect | 85 dB | UL 217

Amazon Affiliate Disclosure: the link below is an Amazon affiliate link. WC Safety earns a commission on qualifying purchases at no additional cost to you.

Legacy First Alert Models and Their Replacements

First Alert’s catalogue has rolled over to the SM/SMCO Precision Detection line and the SC5 smart family. Every alarm this guide previously ranked is discontinued; each is listed here unranked, without affiliate links, with the replacement First Alert itself names.

Related reference

See also UL 217 8th Edition explained — the three new tests behind the standard every current alarm is certified to.

Related on this site: where to install smoke detectors, 10 year sealed vs replaceable battery smoke alarms, how long do smoke detectors last? (2026 guide), best battery smoke detector 2026, best hardwired smoke detector 2026, and best photoelectric smoke detector 2026.

Why trust WC Safety

WC Safety is an independent, affiliate-supported review site. It is not a retailer: it holds no inventory, takes no orders, and earns only from qualifying purchases through clearly marked links — which never changes what a product is rated to do. Standards language is taken from the regulation text directly, and ratings are reported as the manufacturer publishes them. We run no laboratory and perform no testing of our own. Where published sources disagree, we say so and plan on the conservative figure rather than the flattering one.

Our methodology

Why there are no scores on this page. We removed the star ratings in August 2026. They implied a precision we could not justify: WC Safety runs no laboratory and tests no products, so there was no formula, no weighted criteria and no measurement behind the difference between 4.6 and 4.7. What remains is what we can actually stand behind — the manufacturer’s published specification, its current lifecycle status, and a plain statement of what each alarm suits.

Figures come from the regulation and the published specification, in that order. Derated numbers are calculated, not estimated. Nothing here is presented as a measured result, because we measure nothing.

Researched and written by Steven Eaton, editor of WC Safety. Steven holds no safety certification and does not test products; this page compares what manufacturers and regulators publish, with the gaps in that record marked. Last reviewed August 2026.

Affiliate disclosure: as an Amazon Associate, WC Safety earns from qualifying purchases. WC Safety is not a retailer and takes no orders — links go to the seller, and the price you pay is unchanged.

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