With visible bulbs, the bulb is the design – and in every other light it decides the mood and usability. Four numbers are enough to find the right one.
Lumen: how bright
Lumens are the luminous flux, watts only the consumption. As a guide: an old 40 W incandescent bulb gave 400 to 470 lm, 60 W about 800 lm. For mood lighting with a visible filament, 200 to 400 lm per bulb is enough – more dazzles when the filament is exposed. Over the dining table with three pendants: 3 × 400 lm. Under a shade or in the kitchen: 600 to 800 lm per light point. At the desk in the office: 800 lm, directed.
Kelvin: how warm
The colour temperature. 2200 K is the candle and vintage light of filament bulbs, 2700 K the classic incandescent light, 3000 K neutral-warm, 4000 K neutral white (office, workshop), 5000 K and above daylight white (photography, lab). For living spaces: 2200 to 2700 K. In the kitchen, 3000 K is fine if the worktop is being lit. Two different kelvin values in the same room almost always look wrong – so keep all the pendants over the table the same.
CRI: how true the colours are
The colour rendering index (Ra or CRI, maximum 100) tells you how natural colours look under the light. Cheap LEDs have 80, good ones 90, very good ones 95 and above. Above the dining table and in the kitchen, CRI 90+ makes a visible difference: tomatoes are red, not orange, wood has depth. For mood lighting in a corner, 80 is fine.
Dimming
An LED bulb is only dimmable if it explicitly says so. Non-dimmable LEDs on a dimmer flicker or break. And the dimmer has to suit the LED: trailing edge is the safe choice for LEDs. For plug-in lights, dimming works via an inline dimmer instead of an inline switch – in the configurator under “Switch” → “Dimmer”. Smart bulbs dim via the app and don't need a dimmer, but a permanently powered lamp holder.
Shape and glass
For exposed bulbs, shape is what counts: globe (G95, G125, G150) for large spheres above the table, Edison ST64 for the slim vintage look, drop and candle for E14, tube T30/T45 as a line. Clear glass shows the filament best but glares above 400 lm; smoked and gold glass reduce brightness and glare and add warmth; opal glass makes an even sphere with no visible filament; porcelain effect (matt white) glows as a whole surface. In the configurator, glass colour and shape are the two filters in the bulb step.
Lifespan and replacement
LED filament bulbs last 15,000 hours – at four hours a day, that's ten years. If you need a replacement, the item number on your invoice gets you exactly the same bulb again; the range stays the same for years.