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Laser measure vs phone LiDAR, and the question both sides skip
Two decent comparisons rank for this now and both answer the same way, by arguing which device is more accurate in the hands of a professional. That is not the question most remodelers are actually asking.
What the two comparisons out there say
Credit where it is due, the results for this phrase are better than they were. Two vendor pages answer it directly now. The rest of page one is academic papers about streambeds and building facades, a couple of land surveying pages that mean something different by lidar, and the usual parked domains serving best laser measurer listicles.
The first, from a floor plan app, compares pen and paper against a laser measure against phone LiDAR. It gives no numbers at all. Laser is faster and more accurate than pen and paper but still needs manual entry. LiDAR provides highly accurate measurements and often finishes a room in under a minute. That is the whole of it.
The second, from a scanning app, does give numbers, and they are worth repeating with the caveat that they are the vendor's own and arrive with no test method attached. It claims iPhone Pro LiDAR lands within one to two centimetres per wall, a laser distance meter within one to two millimetres per measurement, and phone photogrammetry somewhere between five and fifteen centimetres per wall. It also notes something true and usually missed, that a laser is the most accurate per individual measurement but a floor plan drawn from those measurements reintroduces a human error it does not quantify.
Both pages are written for the same reader, a professional deciding what to carry. Neither is written for the reader who cannot get to the room.
The accuracy argument, honestly
For what it is worth, here is the version that holds up on a job site.
A laser distance meter is more accurate than a phone, measurement for measurement, and it is not close. If you are ordering a shower glass panel or a run of cabinets, you measure it yourself with a laser or a tape, and you measure it twice.
A phone with LiDAR is looser per measurement and far better at the other part, which is capturing a whole room without anybody writing anything down. The error that actually ruins estimates is rarely the sixteenth of an inch. It is the wall nobody measured, the number transposed into the wrong row, the alcove nobody noted.
So they fail differently. A laser is precise and easy to transcribe wrong. A scan is looser and hard to leave a gap in. That is the trade, and nobody arguing centimetres is talking about it.
The question neither one asks
Here is what a remodeler with eleven leads and one truck is actually asking. Not which device is more accurate in my hand. Whether a number captured by somebody who is not me is good enough to quote from.
Neither comparison touches it. Both assume the person holding the device is the person who needs the measurement, and both assume that person is standing in the room. Read them end to end and there is nothing about operator skill, nothing about verifying somebody else's capture, nothing about what you do when nobody qualified is on site.
That is the whole difference in practice. A laser measure in your van is perfectly accurate and perfectly useless when the house is forty minutes away and you have not been to it. A phone in the homeowner's hand is less precise and it is there.
- To quote from: a scan, or typed sizes plus photographs, is usually enough
- To order materials from: your own tape or laser, on site, measured twice
- To settle an argument in six weeks: the photographs, with the dimensions attached to them
Which tool for which job
| Laser measure | Phone LiDAR | |
|---|---|---|
| Accuracy per measurement | Millimetres, per the vendor claims | Centimetres per wall, per the vendor claims |
| Whole room captured | Only what you remember to measure | Whatever the walk covers |
| Transcription error | Every number typed by hand | No typing |
| Works when you are not there | No | Yes, if the person in the room has a recent iPhone Pro |
| Good enough to order glass | Yes | No, verify first |
| Record of what was there | Numbers on a pad | Photographs and dimensions together |
Both sets of accuracy figures above are claims from companies selling the tools, published with no test method. Treat them as a guide to the order of magnitude and nothing finer.
Questions contractors ask
Which iPhones have the LiDAR sensor?
The Pro and Pro Max models from the iPhone 12 generation onward, plus the iPad Pro. The plain non Pro iPhones do not have it, which is exactly why any product leaning on it needs a fallback.
What happens on a phone without LiDAR?
The fallback is photographs plus the room sizes typed in. That is a real answer and it is also the honest limit. Nobody measures a room from a photograph, whatever the marketing says.
Should I stop carrying a laser measure?
No. Carry it. Measure the things you are ordering from. What changes is how many houses you drive to before you know whether the job is worth having.
How do I check a measurement somebody else took?
Pick two dimensions you can verify cheaply, usually the longest wall and the ceiling height, and check those on your first visit. If they are right the rest usually is. If they are not, you know to measure the whole room again before anything gets ordered.
Is a scan accurate enough to price a bathroom?
For a quote, usually yes. For a frameless glass enclosure, no. The working rule is that a scan is good enough to decide and to price, and not good enough to order from.
See what comes back
Send the link to the next homeowner who calls and set the submission against your own notes from the last job you drove out to. Two scans are free and there is no card. Whatever you pay now is what you keep paying while the account is open, and that offer ends on November 30.