First Alert SMI100-AC
Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
Price as of 2026-06-05. Check Amazon for the current price.
Quick Decision
Price Intelligence
Currently $19.49 — $2.80 below the 90-day average of $22.30.
All-time low: $16.20 on Tue Sep 30 (from 182 price checks).
- Budget:$17–$39← You are here
- Mid-range:$39–$93
- Premium:$93+
Is This Right For You?
- •Budget-conscious shoppers — priced below 92% of Smoke Detectors
- •Top 5% bestseller in Smoke Detectors — proven market demand
- •First Alert loyalists — the brand spans 100 products in our database
- •BRK First Alert 9120BFF/ SMI100-AC Smoke Detector offers a better rating (4.7/5) at a similar or lower price ($19)
- •BRK First Alert 9120BFF/ SMI100-AC Smoke Detector — higher rated at 4.7/5 ($19)
📊 Based on data analysis of 37 products in this category.
Mubboo Score: A
How we calculate the Mubboo Score
Quality (45%): customer rating, normalized to a 10-point scale
Popularity (35%): review volume vs the category leader, log-scaled
Value (20%): price position vs other Smoke Detectors
Computed from live Amazon rating, review count, and price across 37 Smoke Detectors available to US consumers · last refreshed 2026-06-05.
How It Compares
This Product First Alert SMI100-AC | Most Popular BRK First Alert 9120BFF/ SMI100-AC Smoke Detector | Best Rated Kidde Smoke Detector | Best Value First Alert Smoke Alarm | |
|---|---|---|---|---|
| Price | $19.49 | $18.99 | $19.88 | $16.99 |
| Rating | 4.6/5 | 4.7/5 | 4.6/5 | 4.6/5 |
| Reviews | 2,162 | 19,205 | 7,603 | 4,421 |
| Mubboo Score | A | A+ | A+ | A+ |
Quick Specs
- Alarm
- Smoke Alarm
- Color
- White
- Style
- Precision Detection
- Unit Count
- 1.0 Count
- Item Weight
- 0.6 Pounds
- Sensor Type
- Ionization
- Manufacturer
- Resideo
- Model Number
- SMI100-AC
What People Say
Synthesized from 40 reviews · 100% verified purchases.
Test units upon arrival, as included batteries may be dead or drain quickly. Verify activation tab functions and note that sealed-battery models may not interconnect with other alarms.
- Ease of Installation
- Good Value
- Reliable Performance / No False Alarms
- Compatibility with Existing Mounts
- Long Battery Life / No Battery Changes
- Pre-installed Battery Drains Quickly
- Dead on Arrival / Activation Issues
- Flimsy Build Quality
- Confusing Instructions
Expert Picks in Smoke Detectors
- Kidde Smart Smoke Detector — Best smoke detector overall
- First Alert Battery Smart Smoke & Carbon Monoxide Alarm with Nest Protect — Best for Google Nest users
- Kidde Ring-Enabled Smart Smoke and Carbon Monoxide Detector — Best smoke detector for Alexa and Ring users
- First Alert SMI100 Dual Sensor Smoke Detector — Best budget smoke detector
Category recommendations from independent expert publications. Source links in References.
Related Video Reviews
Key Features
- ✦First Alert's Precision Detection advanced sensing technology complies with new industry standards to reduce cooking nuisance alarms and provides early warning in the event of a ho…
- ✦Through early warning interconnect, when one alarm sounds, all compatible alarms will sound
- ✦Battery backup provides continuous protection during power outages
- ✦Alarm indicator visually identifies the unit that initiated the alarm
- ✦Quick Connect Plug included allows for easy installation with no need to rewire
Source: product listing on Amazon.
About First Alert
- 100 products in our database
- Average rating: 4.6/5 across all products
- Price range: $13.98 – $648
- Categories: Carbon Monoxide Detectors, Fire Extinguishers, Smoke Detectors
If not the SMI100-AC, consider these
Featured in Our Reviews
Bottom Line
First Alert SMI100-AC earns Mubboo Score A. At $19 it's $3 below the 90-day average and near its lowest tracked price — a good time to buy. Rated 4.6/5 from 2,162+ reviews. Strong buy if: budget-conscious shoppers, top 5% bestseller in smoke detectors. Skip if: brk first alert 9120bff/ smi100-ac smoke detector offers a better rating (4.7/5) at a similar — BRK First Alert 9120BFF/ SMI100-AC Smoke Detector (Score A+, $19) may fit better.
Frequently Asked Questions
Is the First Alert SMI100-AC worth buying in 2026?
It earns a Mubboo Score of A, with a 4.6/5 rating from 2,162 reviews — better than 78% of Smoke Detectors we track.
How much does the First Alert SMI100-AC cost?
It is currently $19.49. The 90-day average is $22.30 and the all-time low we recorded is $16.20.
How does the SMI100-AC compare to other Smoke Detectors?
The category's most-reviewed alternative is the BRK First Alert 9120BFF/ SMI100-AC Smoke Detector (4.7/5, 19,205 reviews, $18.99). The SMI100-AC carries a Mubboo Score of A vs A+.
Sources & References
Products available through US retailers. Prices in USD. Sales tax varies by state and is not included.
Mubboo may earn a commission on purchases made through affiliate links. This does not affect our Mubboo Score, product rankings, or editorial judgments. Prices are accurate as of the last sync (2026-06-05) and may change.