Lighting (Lumen) Calculator
Calculate the required lumen output and LED bulb options based on room type and area.
This calculation provides estimated values based on EN 12464-1 and IESNA standards. Ceiling height, surface colour and fixture type can affect the result; consult a professional lighting designer for critical projects.
How to Calculate Lighting Requirements by Square Metre
The basic formula is straightforward: Area (m²) × Target lumen/m² = Required total lumens. For example, a 15 m² kitchen requires 15 × 200 = 3,000 lm. You can meet this with one large bulb or several medium-power LEDs. The tool performs this calculation automatically and lists bulb options for you.
What Is the Difference Between Watt and Lumen?
Watt is the amount of energy the bulb consumes — it affects your electricity bill. Lumen is the amount of light the bulb emits — it shows actual brightness. In the incandescent era, 60 W = 800 lm was a fixed reference. In the LED age, 8–10 W can produce 800 lm, so wattage is no longer an indicator of brightness. When choosing a bulb, look at the lumen value on the packaging, not the wattage.
Ideal Lumen Values by Room
The values below are based on EN 12464-1 standard and assume a standard ceiling height (2.5–2.7 m) with mid-tone surfaces.
| Room Type | Target Lumen/m² | Purpose |
|---|---|---|
| Living Room | 150 lm/m² | Comfortable reading and social activity |
| Kitchen | 200 lm/m² | High visibility for cutting and cooking |
| Bedroom | 100 lm/m² | Calm, low light; supports sleep quality |
| Study / Office | 500 lm/m² | Extended screen or paperwork sessions |
| Bathroom | 250 lm/m² | Safe movement and personal care |
| Hallway / Corridor | 100 lm/m² | Sufficient orientation for a transit area |
| Garage | 150 lm/m² | Vehicle maintenance and safety |
How to Choose LED Bulbs
Once you know your total lumen requirement, dividing it across several medium-power bulbs rather than a single powerful one provides more uniform and shadow-free light distribution.
Colour Temperature (Kelvin) Selection
2700–3000 K
Warm White
Living room, bedroom
4000 K
Neutral White
Kitchen, bathroom
5000–6500 K
Cool White
Study, garage
CRI (Colour Rendering Index)
CRI measures how accurately a bulb renders the true colours of objects (scale 0–100). CRI ≥ 80 is sufficient for everyday use. For colour-sensitive areas such as makeup mirrors, workshops or galleries, choose CRI ≥ 90.
Key Considerations in Lighting Design
- Ceiling height: Increase lumen requirements by 20–30% for ceilings above 3 metres; light weakens by spreading before reaching surfaces.
- Surface colour: Dark walls and floors absorb light; light-coloured surfaces allow the same comfort with fewer bulbs.
- Task lighting: Add task lighting to work desks and kitchen counters in addition to general lighting; it reduces eye strain.
- Dimmer: Using dimmer-compatible LED bulbs to reduce light intensity in the evening saves energy and supports the circadian rhythm.
- Light distribution: Distributing several medium-power bulbs rather than a single powerful one reduces shadow spots. Spotlights, panels and pendant fixtures have different beam angles; plan placement accordingly.