Smoke Detector Installation Cost Calculator
Smoke Detector Installation costs $525 to $775 for a typical 6 devices job in 2026, against a national benchmark of $625. Labor runs 4.4 crew hours at $43.61 an hour. Enter a ZIP code to apply that area's measured wages for this work and its regional price level.
What makes up the price
Cost by size
National averages, before any local adjustment. Computed from the same model as the calculator above, so the two always agree.
| How many | Devices | Typical | Range |
|---|---|---|---|
| 3 devices | 3 | $375 | $310 to $465 |
| 5 devices | 5 | $550 | $445 to $675 |
| 6 devices | 6 | $625 | $525 to $775 |
| 8 devices | 8 | $800 | $650 to $1,000 |
| 10 devices | 10 | $975 | $800 to $1,200 |
Turn one over and read the date
Before anything else on this page, go and take one alarm off its bracket and look at the back. There is a manufacture date printed on it.
Smoke alarms expire ten years from that date — not from when you installed them, and not from when they last beeped on test. The sensing element degrades on a timetable: an ionization chamber loses its source, a photoelectric sensor's chamber accumulates dust and its optics drift. An alarm past ten years can pass its own test button, which only proves the horn and the battery work, and still fail to detect a fire in time.
That is the single most useful thing on this page, and it is why alarms are a set replacement rather than a running repair. They were almost certainly all fitted on the same day, which means they all expire within weeks of each other.
| Alarms on one visit | Total | Each |
|---|---|---|
| 1 | $205 | $205 |
| 6 | $625 | $104 |
Doing them one at a time as they fail costs twice as much and leaves you with a mixed-age set, which matters for the next section.
Interconnection is the feature worth having
Hardwired alarms in a modern house are interconnected: when one detects smoke, every alarm in the house sounds.
That is not a convenience. A fire starting in a basement or a garage at night is detected by the alarm nearest it, which on its own is too far away to wake somebody upstairs through a closed door. Interconnection is what turns a detector into a warning.
Two practical consequences:
- Replace them as a set, with one brand. Interconnect signaling is not standardized between manufacturers on the traditional three-wire system, so mixing brands commonly breaks the link — sometimes silently, so everything looks fine until it matters. If an electrician is replacing some of your alarms, replace all of them.
- If your alarms are not interconnected, wireless interconnected models exist that pair to each other over radio and need only power. On a house with hardwired-but-not-linked alarms, that is the upgrade worth asking about, and it avoids running new three-conductor cable between every alarm.
Ionization or photoelectric, and why you want both
The two sensing technologies answer different fires, and this is not marketing.
| Detects | Faster at | |
|---|---|---|
| Ionization | Changes in a small ionized air gap | Fast, flaming fires |
| Photoelectric | Light scattered by particles | Slow, smoldering fires |
The difference is substantial rather than marginal — photoelectric alarms respond meaningfully sooner to a smoldering sofa or a cigarette in bedding, which is the kind of fire that kills people in their sleep. Ionization responds sooner to a flash fire in a pan.
Dual-sensor alarms carry both and are the sensible default. Where you are fitting single-technology alarms, photoelectric near bedrooms is the priority, and photoelectric is also far less prone to the cooking nuisance trips that get alarms taken down.
Where they go, and the one that gets missed
Required placement in a dwelling:
- Inside every bedroom.
- Outside each sleeping area, in the hallway serving the bedrooms.
- On every level, including the basement and any finished attic.
Positioning details that matter:
- At least 10 feet from a cooking appliance, which is the single biggest cause of nuisance alarms and of alarms being disabled.
- Not within 3 feet of a bathroom door, for the same reason with steam.
- Not in the dead air space in the apex of a peaked ceiling — mount 4 to 12 inches down from the peak.
- Away from supply registers and ceiling fans, which blow smoke away from the sensor.
The one that gets missed: a finished basement with a bedroom in it needs an alarm in the bedroom, one outside it, and one for the level — people fit one and consider it done.
Carbon monoxide is a different hazard
Worth stating plainly because the assumption is common: a smoke alarm does not detect carbon monoxide, and a carbon monoxide alarm does not detect smoke. They are unrelated sensors answering unrelated dangers.
If the house has any fuel-burning appliance — gas furnace, gas water heater, gas range, fireplace, wood stove — or an attached garage, it needs carbon monoxide alarms as well, and most jurisdictions now require them. CO alarms are typically required outside each sleeping area and on every level.
Combination smoke and CO alarms exist and cost $35 to $60 against $18 to $30 for a plain smoke alarm. Fitting combination units outside the bedrooms and on the level with the furnace, with plain smoke alarms elsewhere, is the usual sensible arrangement — and is what the blended device price in the figure above assumes.
One difference to know: CO alarms have a shorter life than smoke alarms, typically 7 to 10 years. A combination unit expires on the shorter of the two.
What you are paying for
For six hardwired alarms replacing existing ones on an existing interconnect, at $625:
| Labor, about 3.75 hours | around $229 |
| Six alarms with battery backup | $192 |
| The call-out | $45 |
| Overhead and margin | the balance |
Half an hour per alarm sounds generous for something that twists off a bracket. It is not: each one has to be fitted, paired to the others and then the interconnection tested from every alarm in turn, because an interconnect that works in one direction and not another is exactly the failure this system exists to prevent.
If an electrician replaces six alarms and tests only one, they have not finished the job.
Can you do it yourself?
Replacing a hardwired alarm is genuinely within reach. They twist off a bracket and unplug from a push-fit harness; the common catch is that a new alarm's harness may not match the old bracket, which usually means changing the bracket and occasionally re-terminating three wires in the box.
Do it yourself if: you are replacing like for like with the same brand, you can turn the circuit off and prove it, and you will test the interconnection from every alarm afterwards.
Pay somebody if: there is no existing interconnect and you want one, the wiring is old or ungrounded, there is no alarm where code requires one, or you simply want the whole set done and tested properly in an hour.
Either way, replace the whole set at once and write the installation date on the inside of a cupboard door.
Questions worth asking
- What is the manufacture date on the existing alarms?
- Are these interconnected, and will you test it from every alarm?
- Will all of them be the same brand?
- Dual-sensor, or photoelectric near the bedrooms?
- Do we have carbon monoxide coverage, and where is it required here?
- Is there an alarm in every bedroom, outside each sleeping area and on every level?
- Is any alarm within 10 feet of the stove, and can it be moved?
- Can wireless interconnect be used instead of running new cable?
- Can this be done on the same visit as anything else electrical?
Common questions
How much does smoke detector installation cost?
About $104 each when six hardwired alarms are replaced on one visit, which is $625 for the set. One on its own is $205, because the electrician's call-out is most of a single-alarm job. That is the argument for doing them together — and alarms were almost certainly all fitted on the same day, so they expire within weeks of each other anyway.
How often should smoke alarms be replaced?
Every ten years from the manufacture date printed on the back of the unit — not from when you installed it, and not from when it last passed a test. The sensing element degrades on a timetable: an ionization chamber loses its source and a photoelectric sensor accumulates dust and drifts. An alarm past ten years can still beep on test, which only proves the horn and battery work, and fail to detect a fire in time. Go and turn one over.
Does a smoke alarm passing its test mean it works?
Only partly. The test button checks the horn, the battery and the electronics — it does not test the sensor's ability to detect smoke. That is why the ten-year replacement rule exists independently of testing, and why an alarm that beeps reassuringly every month can still be past its useful life. Test monthly for the things the button does check, and replace on the date regardless.
Why do all my smoke alarms need to be the same brand?
Because interconnect signaling is not standardized between manufacturers on the traditional three-wire system, so mixing brands commonly breaks the link — and often silently, meaning everything looks fine until the night it matters. Interconnection is the feature worth having: a fire in a basement is detected by the alarm nearest it, which alone is too far to wake somebody upstairs through a closed door. If some alarms are being replaced, replace them all.
What is the difference between ionization and photoelectric smoke alarms?
They answer different fires. Ionization alarms sense changes in a small ionized air gap and respond faster to fast, flaming fires such as a flash fire in a pan. Photoelectric alarms sense light scattered by particles and respond meaningfully sooner to slow, smoldering fires — a sofa or bedding, which is the kind that kills people in their sleep. Dual-sensor alarms carry both and are the sensible default. Where you must choose, photoelectric near bedrooms, which is also far less prone to cooking nuisance trips.
Where are smoke alarms required?
Inside every bedroom, outside each sleeping area in the hallway serving the bedrooms, and on every level of the house including the basement and any finished attic. The placement that gets missed is a finished basement containing a bedroom — that needs one in the bedroom, one outside it and one for the level, where people commonly fit a single alarm and consider it done.
Why does my smoke alarm go off when I cook?
Almost always because it is too close to the stove. Alarms should be at least 10 feet from a cooking appliance, and not within 3 feet of a bathroom door either, since steam does the same thing. Nuisance alarms are the main reason detectors get disabled, which is why moving one is worth doing properly rather than living with. Photoelectric sensors are also considerably less prone to cooking trips than ionization ones.
Where should a smoke alarm not be placed?
Within 10 feet of a cooking appliance, within 3 feet of a bathroom door, in the dead air space right at the apex of a peaked ceiling — mount 4 to 12 inches down from the peak — and anywhere a supply register or ceiling fan will blow smoke away from the sensor. Each of those produces either nuisance alarms or a detector that is slower than it should be, and both end the same way, with somebody taking the battery out.
Do smoke alarms detect carbon monoxide?
No, and the assumption is common enough to be worth stating plainly. They are unrelated sensors answering unrelated hazards: a smoke alarm does not detect CO and a CO alarm does not detect smoke. Any house with a fuel-burning appliance — gas furnace, gas water heater, gas range, fireplace, wood stove — or an attached garage needs carbon monoxide alarms as well, and most jurisdictions now require them outside each sleeping area and on every level.
Should I buy combination smoke and carbon monoxide alarms?
Usually for some of them. Combination units cost $35 to $60 against $18 to $30 for a plain smoke alarm, and the sensible arrangement is combination units outside the bedrooms and on the level with the furnace, with plain smoke alarms elsewhere. One thing to know: CO sensors have a shorter life than smoke sensors, typically 7 to 10 years, so a combination unit expires on the shorter of the two.
Can I replace a hardwired smoke alarm myself?
Usually yes. They twist off a bracket and unplug from a push-fit harness, and the common catch is that a new alarm's harness may not match the old bracket — which means changing the bracket and occasionally re-terminating three wires in the box. Do it yourself if you are replacing like for like with the same brand, can turn the circuit off and prove it, and will test the interconnection from every alarm afterwards. Pay somebody if there is no interconnect and you want one, the wiring is old, or an alarm is missing where code requires one.
Can smoke alarms be interconnected without new wiring?
Yes — wireless interconnected models pair to each other over radio and need only power, so they work on a house with hardwired alarms that were never linked. That avoids running new three-conductor cable between every alarm, which in a finished house is the expensive part by a wide margin. If your alarms sound individually rather than together, this is the upgrade to ask about, and it is the main reason to mention the existing setup when booking.
Where these numbers come from
Nothing here is copied from a contractor directory. Labor is priced from what the trades are actually paid, materials from published producer prices, and both are adjusted to your area using federal cost-of-living data.
- Electrical contractors, United States: $43.61/hour, August 2026 (BLS CES CES2023821003)
- Hardwired smoke alarm with battery backup: $32.00 per alarm (price recorded October 2026, not index-adjusted)