Meters
Hioki FT3425, on iPhone and iPad.
The FT3425 is a handheld lux meter made by Hioki. It connects to Luxwork over Bluetooth, and readings arrive on the plan as you take them. Luxwork is launching on iPhone and iPad in autumn 2026.
What comes across the link
- The reading exactly as the display shows it. The FT3425 sends the number on its screen, so Luxwork records it with the same decimal places. A meter showing 443 is recorded as 443, not 443.0.
- The model and serial number. Luxwork reads them before it will record anything, so every reading is tied to the instrument that took it.
- The range the meter is on. One of its five ranges, from 20.00 lux up to 200,000 lux, and whether it is on auto range. Luxwork records the range with every reading.
The FT3425 doesn't send its battery level over Bluetooth, so keep an eye on the battery symbol on the meter's display.
What Luxwork refuses
The FT3425 tells Luxwork when the number on its screen isn't a live reading. In each case Luxwork records nothing and shows an amber message saying what to do.
| HOLD is on | The value on screen is frozen. Press HOLD on the meter to release it, then capture. |
|---|---|
| Over range | The light is above the fixed range the meter is set to, so there is no value to record. Hold RANGE for a second to go back to auto range. |
| Changing range | On auto range the meter takes a moment to settle on a new range. Wait a second, then capture. |
If the link drops, Luxwork won't record the last number left on screen. It waits for a fresh reading.
Before you start
- Turn Bluetooth on at the meter. Hold ▼ (READ) and RANGE together for a second. The maker's manual says the setting stays on after you switch the meter off.
- Unplug the USB cable. The maker's manual says the Bluetooth setting can't be changed while the USB cable is connected.
- One phone at a time. The meter talks to one device at once. If it is connected to another phone or app, disconnect it there first.
- Stay in range. The maker gives about 10 m in line of sight, and says walls and metal shorten it. The meter beeps each time it connects or disconnects.
How to do a workplace lighting survey covers the method itself.
What the report records
- The meter's make, model and serial number.
- The calibration certificate you recorded for that serial number, and whether it was in date on the day.
- The range the meter was on for the readings, for example "range 200 lx, auto".
- Each reading, at its point, with the time it was taken, to the resolution the meter displayed.
What a lighting survey report should contain shows the rest of the report on a specimen.
Luxwork's status
Luxwork, a lighting survey app for iPhone and iPad, is launching in autumn 2026. Hioki also offers its own app for the FT3425. This page is only about what Luxwork does with the meter: it lays out the grid for the method you choose, judges the survey against the rule set you chose, prints the statistics and the conditions you confirmed, and produces a signed record.
Test Luxwork before launch
Testing is on iPhone and iPad. We'll invite testers in small groups through Apple's TestFlight.
Hioki makes the FT3425. Luxwork is made by UberVisor Ltd and is not a Hioki product. The meters page says how readings get into Luxwork. It says nothing about how good a meter is.