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How to use a lux meter

Updated: 22 October 2026

The number will not sit still the first time. You move, a cloud moves, the cap is on, or the screen says foot-candles while your chart is in lux. This is how to use a lux meter so next week's reading is about the light, not about how you held it. You need one repeatable spot, not a survey of the house. The [lux meter comparison](/hub/measuring-equipment/lux-meter) is the table if you are still choosing. Peter F. took the steps from the listings, the UK review notes, and public UK guidance. We did not visit your room. A qualifying purchase can earn a commission at no extra cost to you.

The number will not sit still the first time. You move, a cloud moves, the cap is on, or the screen says foot-candles while your chart is in lux.

Our top picks

TopTes TopTes TS-710

Best overall

TopTes TopTes TS-710
8.2/10about £29.99
View offer
Dr.meter Dr.meter 1010BS split

Best value

Dr.meter Dr.meter 1010BS split
6.1/10about £18.99
View offer
URCERI URCERI handheld

Alternative

URCERI URCERI handheld
6.8/10about £29.99
View offer
On this page
  1. 1.Set the meter before you trust it
  2. 2.Put the sensor on the plane that matters
  3. 3.Write down what the number is
  4. 4.Where this stops

Set the meter before you trust it

Take the cap off before you call the room dark. A UK note on the ALLmeter says the lux figure appears once the cover is off. A zero is often the cap, a flat cell, or the wrong range. UK charts are in lux, and one foot-candle is about 10.76 lux, so switch to lux for the whole session. On the Dr.meter 1010BS both upper ranges say ×10. A display of 500 on the wrong range is not 500 lux. Write the range down. Which head you bought is the lux meter buying guide.

Put the sensor on the plane that matters

Survey write-ups often put a desk plane at about 0.75 metres. That is a common working height, not a figure in the Workplace (Health, Safety and Welfare) Regulations 1992. A corridor is the floor. A plant is the leaf. Lay the cell flat, facing the light. Your body is the usual error. The Institution of Lighting Professionals notes that a remote head cuts that shadow. On a split meter, leave the cell down and read the body from the side. On the TS-710, turn the stated 180° head toward the lamp. On a fixed head, set the meter down and step back. Use hold before you lean in. Do not shade the cell.
TopTes TopTes TS-710

Testsieger

TopTes TopTes TS-710
8.2/10about £29.99
View offer

Write down what the number is

A bare lux figure is useless next week. Write the lamp, whether daylight was in the room, the time, and the plane. "320 lux, desk, ceiling LED only, curtains closed, 7 pm" can be compared later. "320" cannot. UK reviews of the TS-710 and the URCERI say the digits jump when the light flickers or cloud crosses a window. Wait for a smaller swing, or note max and min if those keys exist. If the room looks lit and the meter says almost nothing, check the cap, the range, and the unit before you change the lamp. Three spots on the same plane are still not a signed grid.

Where this stops

Cap off, lux selected, cell on the plane you named, body clear: that is a home reading. HSE's HSG38 gives examples such as 200 lux average where work needs detail. Those numbers are context, not a tick-list for a pocket meter. Regulation 8 publishes no lux table you can complete here. Stop for an office grid, emergency-lighting duration, or fixed wiring. A UK reviewer used a TS-710 on emergency lights. That checks a fitting. It is not BS EN 1838. Grow light is lux meter for plants.

Common questions

Where do I hold the sensor?
Put it on the plane you chose, flat, cell towards the light, and keep your body out of the beam. About 0.75 metres is a common desk height in survey notes, not a legal mark. Measure the floor in a corridor and the leaves for a plant. A split head or a swivel lets you see the screen without leaning over the cell. A fixed head means you set the meter down and step back.
Why does the number jump when I move?
You are changing the shadow and the angle. A small step can block the lamp, and cloud or a dimmer moves the light itself. UK reviews describe readings that will not settle on an unsteady source. Wait, use hold or max and min if you have them, and stand in the same place next time. If it jumps with the meter parked and the lamp steady, check the range and the battery.
The screen says fc. Can I compare it with a UK chart?
Not until you switch to lux. One foot-candle is about 10.76 lux, so 500 fc is closer to 5,380 lux, not to a chart that says 500 lux. Change the unit and take the reading again. Keep one unit in the note. Mixing them makes next week's comparison meaningless.
What if the reading is zero?
Check the cap, the cells, and the range before you assume the room is dark. A cover left on is a common zero. On the 1010BS the wrong range misleads you because both upper ranges are printed as ×10. If the display is lit, the cell is bare in a bright room, and the figure stays at zero, suspect the sensor rather than the lamp.
How do I use a meter with three ranges?
Pick the range that shows a readable number, then multiply by the factor printed for it. On the 1010BS the low range is a straight reading and both higher ranges say ×10. Write the range beside the lux figure so you can repeat it. If you do not want that arithmetic, choose a listing that says auto range, and still confirm the screen is in lux.
Is one spot in the middle of the room enough?
It is enough to compare that spot with itself later, under the same lamp and the same note. It is not the room. Corners are often much dimmer. Three written spots on one plane are a fair home check. A grid with uniformity, and a result someone else will rely on, is where a competent person takes over.
Can I check emergency lighting this way?
You can see whether a fitting lights and whether a nearby spot is brighter than the surround. You cannot sign the system off. Emergency lighting under BS EN 1838 and BS 5266-1 includes duration, not one snapshot from an uncertified meter. If the log must stand up, use the meter and the person the scheme names.

Related pages

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Best lux meter: aiming pick, room pick, best value

Lux meter buying guide: sensor, range and the unit

Lux meter for plants: compare spots under one lamp

Sources

Public UK sources from the research digest, last checked on 19 October 2026. Shelf prices and star lines are the amazon.co.uk figures captured with these twelve listings. The price bands are this set, not a market average.

  1. Workplace (Health, Safety and Welfare) Regulations 1992, regulation 8 (retrieved 19 October 2026)
  2. HSE HSG38: Lighting at work (retrieved 19 October 2026)
  3. HSE: Lighting (retrieved 19 October 2026)
  4. HSE L24: Workplace health, safety and welfare (retrieved 19 October 2026)
  5. ILP Guidance Note 7: Choosing a photometer or illuminance meter (retrieved 19 October 2026)
  6. LIA TS23 (retrieved 19 October 2026)
  7. CIBSE LG7: Lighting for offices (2023) (retrieved 19 October 2026)
  8. Michigan State University: Light into perspective (retrieved 19 October 2026)