15㎡ · office desk
6000
lm · 400 lux
15 m² office desk — 6000 lumens
A room at 400 lux needs 6000 lumens. That is 60 watts of LED, or 8 bulbs of 800 lumens.
Watts are not brightness
Equal lumens mean equal brightness; what changes is the electricity. An LED makes 100 lumens per watt, a filament 13 — nearly eight times apart. The monthly figure below assumes five hours a day for thirty days.
- LED100 lm/W60 W
- fluorescent60 lm/W100 W
- halogen20 lm/W300 W
- incandescent13 lm/W461.5 W
- Light reaching the floor
- 400 lux
- Light you need
- 6000 lm
- Room size
- 15 ㎡
- In pyeong
- 4.5
- In 800-lumen bulbs
- 8
- A month of electricity
- 9 kWh
- Extra watts if incandescent
- 402 W
Several lamps beat one
The same lumens crammed into one fitting light the spot beneath and leave the corners dark. Splitting them across several 800-lumen lamps softens shadows, and one failure no longer means a dark room.
Nearby cells
Same room, other uses
Same use, other sizes
3㎡ · office desk
1200lm
4㎡ · office desk
1600lm
5㎡ · office desk
2000lm
6㎡ · office desk
2400lm
8㎡ · office desk
3200lm
10㎡ · office desk
4000lm
12㎡ · office desk
4800lm
15㎡ · office desk
6000lm
17㎡ · office desk
6800lm
20㎡ · office desk
8000lm
23㎡ · office desk
9200lm
26㎡ · office desk
10400lm
30㎡ · office desk
12000lm
33㎡ · office desk
13200lm
40㎡ · office desk
16000lm
45㎡ · office desk
18000lm
50㎡ · office desk
20000lm
60㎡ · office desk
24000lm
70㎡ · office desk
28000lm
80㎡ · office desk
32000lm
How to read this
- The light you need is lux times floor area; the use decides the lux.
- Watts are only that light divided by the lamp’s efficacy — not a measure of brightness.
- Bulb counts round up from one 800-lumen lamp.
- Ceiling height, wall colour and shades are not in this calculation.
Frequently asked questions
Q. How many lumens for a 15 m² office desk?
6000 lumens — 400 lux times the floor area.
Q. How many watts should the lamp be?
60 W as LED, 100 W as fluorescent. An incandescent would draw 461.5 W — 402 W more.
Q. How many bulbs do I need?
8 at 800 lumens each. Spread them out rather than stacking them in one fitting.
Q. What does it cost to run?
On LED at five hours a day, 9 kWh a month.