Most of what I measure on a survey has a hard number attached to it — a moisture reading, a pressure differential, a crack width. Light is different. Nobody’s eye is a reliable instrument for it: a room can feel bright enough on a sunny afternoon and read well under the figure a workplace assessment needs, or feel gloomy under artificial light that’s perfectly adequate on paper. A lux meter takes the guesswork out of that, and it comes up in three quite different jobs.
The clearest is a workplace lighting check against BS EN 12464-1, the standard that sets task-area illuminance for offices, workshops and factories — 500 lux for general office work, up to 750–1,000 lux for technical drawing or fine assembly, down to 300 lux for general factory space. The second is a landlord compliance question with no lux figure actually attached to it: HMO habitable-room standards are built around glazed area, not light readings, but a meter still earns its keep making the case in writing when a room’s daylight is borderline. The third is the one I get asked about most — a homeowner or neighbour worried about daylight loss from a proposed extension or loft conversion, wanting a sense-check before it turns into a formal BS EN 17037 daylight assessment run by a specialist consultant.
None of those jobs need a laboratory-grade photometer. What they need is a meter that reads accurately off-axis, doesn’t get its own reading shadowed by the hand holding it, and holds a stable figure long enough to write down. That’s the shortlist below.
The one I’d buy
Extech LT300
The LT300’s own listing states it uses a precision photodiode with a colour-correction filter, and — the feature that matters most here — a remote light sensor on a 12″ coiled cable, expandable to 24″. That means the sensor sits at the working plane on its own, away from the meter body and the surveyor’s hand, instead of a fixed head that shadows its own reading. A 0–200,000 lux range with 0.01 lux resolution, plus relative and peak modes, covers task-lighting checks and a bright outdoor daylight comparison from the same instrument.
Typically £160–£180
Check price on AmazonHow I judge a lux meter
Cosine correction, not just a headline range. Light rarely hits a sensor straight-on, and a sensor without cosine correction over-reads or under-reads light arriving at an angle — near a window, under an angled fitting, on a sloped rooflight. A manufacturer stating the sensor is cosine and colour corrected is telling you the reading holds up off-axis, not just facing the source directly.
A sensor that isn’t shadowed by the meter itself. BS EN 12464-1 readings are taken at the working plane — roughly desk height, not the floor — and a bulky meter body held close to that plane can shadow its own sensor. A remote sensor on a cable, or a genuinely slim head, avoids the reading being quietly wrong because of how it was taken.
Range matched to the job, not a single big number. Every reading in this guide’s three job contexts sits under 1,000 lux — HSE’s HSG38 guidance puts rough construction work at a 20 lux minimum and a 50 lux aim, precise work at 100 lux minimum and 200 lux aim, and BS EN 12464-1’s office and workshop figures top out around 1,000 lux for fine assembly. A 400,000 lux ceiling only matters for a direct-sun outdoor comparison, not an indoor task check.
Min/Max or Hold, for a reading that won’t sit still. A reading taken under a flickering fluorescent tube, or outdoors as cloud moves across the sun, needs holding or averaging rather than read off a jumping display. Peak and relative modes do the same job for a reading that needs to catch a momentary high or a change between two points.
A stated accuracy figure or calibration certificate, for a reading that has to stand up in a report. A workplace lighting complaint or an HMO licensing dispute is worth backing with a traceable figure rather than a phone photo of a display — the difference between a meter stating ±3 lux against a factory calibration certificate and one stating only a wide accuracy band.
The comparison
| Model | Range | Accuracy | Typical price | Best for | |
|---|---|---|---|---|---|
| Extech LT300 | 0–200,000 lux | Cosine/colour corrected | ~£160–£180 | Best overall | View |
| Testo 540 | 0–99,999 lux | ±3 lux, calibration cert. | ~£180–£195 | Premium/professional pick | View |
| Voltcraft LX-1108 | 0–400,000 lux | ±3% | ~£160–£180 | Widest range / PC logging | View |
| UNI-T UT383BT | 0–199,900 lux | ±(4%+8) | ~£30–£40 | Bluetooth/app logging | View |
| Dr.meter LX1330B | 0–200,000 lux | Not stated on listing | ~£25–£33 | Best on a budget | View |
| UNI-T UT383 | 0–199,900 lux | ±(4%+8) | ~£25–£32 | Compact pocket pick | View |
| URCERI | 0–200,000 lux | ±3%/±4% | ~£28–£36 | Dual lux/temperature reading | View |
The picks in detail
Extech LT300
Best overall — the remote sensor genuinely changes how the reading gets taken
This is the top pick above: a precision photodiode with a colour-correction filter, on a remote sensor cable rather than fixed to the meter body, so the reading is taken at the working plane without the surveyor’s own hand or the casing shadowing it. Digital and analogue bargraph display, relative and peak modes and 0.01 lux resolution at the low end round it out. It’s an older, established Extech design rather than a recent release — no Bluetooth or app export, just a reading on a screen.
For
- Remote sensor on a 12″–24″ cable, away from the meter body
- Cosine and colour-corrected photodiode
- Relative and peak modes for a changing or momentary reading
Against
- No Bluetooth, app export or on-board logging
- No calibration certificate included as standard
Typically £160–£180
Check price on AmazonTesto 540
Premium/professional pick — the calibration certificate in the box
Testo is a name most surveyors already carry other test kit from, and the 540’s listing is explicit about what’s in the box: the meter, a protective cap, an instruction manual and a factory calibration certificate. Its sensor is matched to the spectral sensitivity of the human eye, with ±3 lux accuracy across a 0–99,999 lux range. The sensor sits fixed on the meter body, not on a remote cable, which is the trade-off against the LT300 above.
For
- Factory calibration certificate included as standard
- ±3 lux stated accuracy
- Explicitly marketed for workplace lighting checks
Against
- Fixed sensor, not remote — can shadow its own reading held close to a task plane
- The most expensive instrument in this guide
Typically £180–£195
Check price on AmazonVoltcraft LX-1108
Widest range and PC logging — for mixed artificial lighting and a stored record
The LX-1108 is the outlier here on two counts: a 400,000 lux ceiling across five auto-ranging bands, and a built-in RS-232 port for logging readings straight to a PC. It also lets the light source be selected from four types — sunlight, fluorescent, sodium or mercury vapour — genuinely useful where a workplace mixes daylight and older discharge lighting. The sensor is external on a lead. Stock has run low before — worth checking live availability.
For
- 400,000 lux ceiling, the widest range here
- RS-232 output for a logged PC record
- Selectable light-source type for mixed daylight/artificial readings
Against
- RS-232 needs a USB adaptor on a modern laptop
- Stock levels have run low on this listing before
Typically £160–£180
Check price on AmazonUNI-T UT383BT
Bluetooth/app logging — a stored reading without the premium-brand price
The UT383BT pairs to UNI-T’s free iENV app over Bluetooth for recording, export and storage of readings, on top of the same 0–199,900 lux range, Max/Min and data hold as the standard UT383 below. That’s a useful step for a report that needs a dated reading rather than a photo of a display, at under a quarter of the price of the Testo or Voltcraft picks. Its stated accuracy of ±(4%+8) is looser than either of those.
For
- Bluetooth export to a free app, no PC or cable needed
- Max/Min and data hold built in
- A fraction of the price of the trade-brand picks
Against
- ±(4%+8) accuracy, looser than the premium picks
- Fixed sensor at the top of the meter body
Typically £30–£40
Check price on AmazonDr.meter LX1330B
Best on a budget — the cheapest here, with a PEAK function most budget meters skip
The LX1330B is the least expensive instrument in this guide and still covers the 0–200,000 lux range with FC/Lux switching, a two-readings-per-second response, and a PEAK button that locks in the highest momentary reading — useful for a flickering fitting or a brief flash. Its listing doesn’t state a numeric accuracy figure the way the premium picks do, which is the honest trade-off for the price; a reading from it is a good sanity check, not a number to hang a formal dispute on.
For
- Cheapest instrument in this guide
- PEAK function to catch a momentary high reading
- Two-readings-per-second response
Against
- No numeric accuracy figure stated on the listing
- Fixed sensor, no remote cable
Typically £25–£33
Check price on AmazonUNI-T UT383
Compact pocket pick — no Bluetooth, no fuss, fits a jacket pocket
The non-Bluetooth UT383 covers the same 0–199,900 lux range and ±(4%+8) accuracy as the BT version above, in a slightly smaller, cheaper unit with a large backlit four-digit LCD, Max/Min and data hold. For a quick daylight-adequacy check on an HMO room, or a spot reading to back up a written observation, it’s a sensible pocket instrument that doesn’t need a phone paired to read.
For
- Smaller and cheaper than the Bluetooth version
- Large backlit LCD, Max/Min and data hold
- No app or pairing needed to take a reading
Against
- No logging or export — a written note or photo is the only record
- ±(4%+8) accuracy, the same looser figure as the BT version
Typically £25–£32
Check price on AmazonURCERI Handheld Digital Light Meter
Dual lux/temperature reading — one instrument for two figures
The URCERI reads ambient temperature alongside its 0–200,000 lux illuminance range, on a four-digit colour LCD with Min/Max, data hold and auto power-off. Its stated accuracy steps from ±3% below 10,000 lux to ±4% above it — a modest spec advantage over the plain UT383 and LX1330B at a similar price. The temperature reading is a bonus, not the reason to buy it.
For
- Stated accuracy figure, unlike the cheapest budget picks
- Ambient temperature reading alongside lux
- Colour LCD, easier to read at a glance
Against
- Fixed sensor, no remote cable
- Temperature reading is a minor extra, not a reason to choose it alone
Typically £28–£36
Check price on AmazonWhat actually matters — and what doesn’t
A 400,000 lux ceiling is an outdoor-daylight spec, not an indoor one. Every job in this guide — office task lighting, HMO daylight adequacy, a rough site-lighting check — reads well under 1,000 lux. The wide-range units earn that headroom for a direct-sun outdoor comparison, not for anything measured indoors.
Bluetooth and app export is convenience, not compliance. A dated, exported reading is tidy for a report, but a written figure with a photo of the display has done the job for years and remains acceptable for most of the checks this guide covers.
A calibration certificate matters when a reading has to stand up in a dispute, not for a sanity check. The Testo 540’s factory certificate is worth the premium when a lighting complaint or licensing disagreement needs a traceable figure behind it. For a quick check of whether a room feels darker than it should, any meter here is adequate.
Lux and colour rendering are different measurements. A lux meter reads illuminance — how much light is falling on a surface — not colour temperature or CRI. A room can read a perfectly adequate lux figure under lighting that still looks flat or unflattering.
A lux reading isn’t a daylight assessment. A formal daylight or sunlight impact assessment for a planning application is run under BS EN 17037 by a specialist consultant, using climate-based modelling or a daylight-factor calculation, not a spot reading. What a meter gives a homeowner or surveyor on site is a comparative sanity check, not a substitute for that assessment.
Questions I get asked
What lux level does BS EN 12464-1 actually require?
It depends on the task, not just the room. The standard steps through a fixed scale of illuminance values — 20, 30, 50, 75, 100, 150, 200, 300, 500, 750, 1000 lux and upward — and assigns a figure to the activity: 500 lux for general office work, 300 lux for general factory and workshop space, 750–1,000 lux for technical drawing or fine assembly. Reading the wrong task figure for the room is the most common way this gets misapplied.
Is there a minimum lux level for a bedroom or living room in an HMO?
Not as a standalone figure in most councils’ HMO standards — the yardstick is usually a glazed area equivalent to at least a tenth of the room’s floor area, with a direct view out, and a fallback to adequate artificial lighting where natural light isn’t practicable. A lux reading doesn’t replace that test, but it’s useful evidence where a room’s daylight is genuinely borderline.
Where should a lux reading actually be taken?
At the working plane — roughly desk or worktop height, not the floor — and away from the surveyor’s own shadow or the meter body blocking the sensor. That’s the practical case for a remote-sensor meter like the Extech LT300 over a fixed-head one: the reading comes from where the work happens, not from wherever the meter body sits.
Does a lux meter reading count as a proper daylight assessment for a planning objection?
No. A formal daylight or sunlight assessment for a planning application is run under BS EN 17037, which replaced BS 8206-2 in 2019, using daylight-factor calculations or climate-based modelling by a specialist consultant. A spot lux reading is a useful comparative check — is this room clearly darker than it used to be, or than a similar room next door — not evidence that stands in for that assessment.
A lux meter earns its place for the same reason most of this kit does — it turns “this room feels dark” into a number worth writing down, whether that’s a workplace lighting check, an HMO daylight question, or a sense-check before a neighbour’s extension goes to planning. If you want a building survey that looks at how a property actually performs, not just how it looks on the day, get in touch — or browse the rest of the field-kit guides, including the decibel meter guide this one sits alongside.
Disclaimer. This guide is general information, not a substitute for a formal daylight or sunlight assessment, a workplace lighting audit, or professional advice on HMO licensing standards. Prices are indicative, move constantly and were checked at the time of writing; the linked page always shows the current price. As an Amazon Associate I earn from qualifying purchases.