Photos look entirely different on a different monitor?

I'm worried because, although my photos posted online look fine and contrasty on my monitor, looking at my relatives monitor they come out with a lot less contrast and far, far cooler colours. I checked some other online photos, and it was like this to a small degree but not the same extent.

Is there a setting in Lightroom or Photoshop I have been missing to make sure the same colours are displayed on each monitor? I do use the save for web function with embedded profile.

Nope...

Beyond the sRGB color space for web viewing in general, you really don't have any control over how well setup or not setup someone else's monitor may be.

You might consider including a grey scale on your website and a little text explaining how visitors should see every step from black to white, etc...

Ho hum, looks like I'll have to calibrate. Why can't everyone just have my computer?

Given your Sig, I'm surprised you don't have people to do this for you...

FlyingPhotog wrote in post #12790293
Given your Sig, I'm surprised you don't have people to do this for you...

I'm just deluding myself that I can take good pictures, actually at this rate I have 600 million years to go before I can hold a candle to images like yours.

I get this from time to time when photographing original art pieces for people. I explain that my monitor is color calibrated to my printers/paper/work process. What they might see on their home monitor will probably be vastly different.
Calibrated Apple monitor to a CRT on a PC will look very different. Even the video card can make a huge difference.