Weight limit?

My buddy is 280 and wants to rock climb I have a 10.2 mm rope is there a weight limit? We will only be top rope climbing

Assuming you’re not trolling: yes your buddy can top rope just fine on any UIAA rated climbing rope.

Ropes are rated by the amount of impact force they can withstand. Most 10mm ropes are rated for about 8 Kn. Force = mass x acceleration, in this case acceleration is gravity, 9.8 m/s. So you can solve for the amount of mass a rope can handle in a fall. In this example it would be 816 kg, or 1799 lbs.

Edit: see Greg’s comment below. I don’t know what the impact force rating actually means.

The only concern is the counterweight. 

I wouldn't let em whip on my micro cams, but i'd let em TR on any rope of mine all day.

Cron wrote: Assuming you’re not trolling: yes your buddy can top rope just fine on any UIAA rated climbing rope.

Ropes are rated by the amount of impact force they can withstand. Most 10mm ropes are rated for about 8 Kn. Force = mass x acceleration, in this case acceleration is gravity, 9.8 m/s. So you can solve for the amount of mass a rope can handle in a fall. In this example it would be 816 kg, or 1799 lbs.

Umm. What?  That’s not how the numbers work. 

The impact force rating on ropes tells us the maximum force exerted on a 176 lb climber in a 1.77 fall factor lead fall.  Not the breaking strength of the rope. The number of falls rating tells us how many of these severe falls it takes to break the rope. 
Top rope forces are much lower and don’t really apply here.   
The rope breaking is not a concern. What Paul mentioned could be. 

yeah, if you are a buck twenty you're gonna be in for a long, yet surprisingly short day...

I often climb with partners over 200lb and I weight 145.
When belaying a much heavier leader on sport lead, what happens is you jam your foot in the wall one time, it either breaks or it doesn't and then you learn how to belay a heavier climber. Tip: get close to the wall, put your foot on it and keep your hand off the climbing end of the rope so you don't mangle it when you get sucked into the first bolt. That's for sport at least. If he does lead, heavily consider anchoring yourself if the fall zone is dangerous.
For TR it doesn't really matter too much, just wear gloves and get ready for a workout.