Comments on: How much energy does a modern LCD display use?

Question: How much energy does a modern LCD display use?

thewalrus — Thu, 06 Sep 2012 22:28:37 -0800

If you have a recent 18" to 20" size LCD monitor and a kill-a-watt watt meter, can you please plug it into the watt meter and tell me how much power it's actually drawing?

I am trying to calculate the cumulative Wh load for a small-ish desktop PC setup to be semi permanently installed on a boat. This will include an Intel DN2800 series mini-itx Atom motherboard that consumes a max of about 10.5 watts. I have found various 19" size LCD monitors that claim power consumption of around 25W. How close to a real world figure is this?

For reference I have an old Dell 1907FP 19" 1280x1024 monitor here that is using 32W (as measured by a kill-a-watt) at 100% brightness. Therefore I am hoping that the claimed figure of 25W for a modern 19" to 20" monitor is actually pessimistic on the part of the manufacturer.

By: The Master and Margarita Mix

The Master and Margarita Mix — Thu, 06 Sep 2012 22:43:35 -0800

Check your MeMail.

By: thewalrus

thewalrus — Thu, 06 Sep 2012 22:59:26 -0800

Data point: The Dell 1907FP is 32W-33W at max, or 19W to 20W at 25% brightness. I'm hoping to find data from a post-2011 generation LED backlit model of similar size.

By: PercussivePaul

PercussivePaul — Fri, 07 Sep 2012 00:42:39 -0800

In my experience (PhD student studying energy consumption of office electronics) 25W for a newer 20" monitor is about right and could maybe be on the high side, but not by much. I find manufacturer specs for on power tend to be pretty accurate. I don't have data at hand to confirm this, though.

By: jwells

jwells — Fri, 07 Sep 2012 07:28:12 -0800

None in that range, but two that are close. Here's what I have:



BrandModelDiag. inchesOnClaimedSleep

DellE173FPc1728350

DellE177FPf1721.7400.7

I-INCiH2822781850.5

HP2710m2784900.5

"On" and "Sleep" are in Watts. Note that in the specs for the first one (the oldest I have), the watts are described as "<=".

By: Nelson

Nelson — Fri, 07 Sep 2012 07:57:28 -0800

You may already know this, but by far the biggest power draw for an LCD is the backlight. Setting the brightness down low will consume 50% or less of the power of the brightness at full.

By: Max Camber

Max Camber — Fri, 07 Sep 2012 08:50:03 -0800

Dell P2411H 24" LED backlit

Published specs:
Voltage Required: 100 to 240 VAC/50 or 60 Hz + 3 Hz/1.5 A (Max.)
Power Consumption Operational: 27 W (typical)/ 50 W (maximum)*
Power Consumption Stand by / Sleep: Less than 0.15W
*Maximum power consumption with max luminance, Dell Soundbar, and USB active

Actual numbers (no soundbar or USB):
Max at 100% brightness: 22W
Typical at 70% brightness: 17W
25% brightness: 10W
0% brightness: 7W

At 0% the backlight is still on and the monitor is entirely usable, though not at a level that would be comfortable for an extended period of time.

By: thewalrus

thewalrus — Fri, 07 Sep 2012 14:28:36 -0800

Thanks Max, that's exactly the sort of data I was looking for. I had a strong hunch that 19"-20" LED backlit displays would be sub 25W. If that Dell 24" is 22W at absolute max brightness. a 20" LED unit (Samsung) will probably be around 20W worst case....