If you could provide the elevations from left side to right side (degree of slope toward house) and then the elevation difference at house between yellow line and blue line along with your hypothetical gradient of yellow line it would give a better idea of the overall elevations that your working with/against and allow for better suggestions based on more than photo observation alone.

That information notwithstanding my initial option suggestions would be would be one of or a combination of the following:

install a drain at the center of your patio

build a low retaining wall on the left side and possibly the back of the patio and regrade accordingly

incorporate a rain garden at the back of the patio to collect runoff and regrade accordingly

incorporate a trough, dry creek or rain garden along the left side of the patio and regrade accordingly.

I could be way off, without elevations its a little difficult to gauge the magnitude of the problem.

Your house siding appears to be vinyl or metal. What you don't want to do is have the paver grade up on the siding per the yellow line.

The photo suggests the current grading uses a swale at the dip in the blue line to carry surface water either away from the viewer through the fence gate or toward the viewer to some unseen location.

The critical point that will control possible grading for the patio in the lowest elevation on your property along the route that the swale water takes.

Find and report on that location and elevation and maybe we can help.

So I'm not sure if this is the info you're looking for, but the yellow line has a grading of 1/4" per foot down to the left. The full width of the patio is 19' so the rise from left to right is 4.75".

The left and right points of the blue line are level and the swale dip is about ~2" down in the middle.

pls8xx: That swale carry's water towards you in the picture...though the way our property is setup, would could technically carry the water either toward or away.

Is that the info you guys are looking for?

what is the elevation from back fence to where you would have the back end of your patio?

what do you intend to build the patio out of? smooth perfectly level flagstone, ondulated flagostones or pavers?
If you are using a perfectly level and non permeable surface you can cheat a little on your elevations and extend your gradient to 1/5" (1" over 5') sparing yourself about one critical inch.

The good news is your only dealing with a 2" drop for the swale indicating that the runoff will be manageable. If you install a drain on your patio at centre or to left of centre, you can maintain roughly the existing elevations and your patio gradient will not be so much that it will inconvenience chair or table legs.

An even better solution may be to install a rain garden that borders the left side of your patio and possible along the back side. This will be aesthetically pleasing, and will serve functional purpose for water control and bordering and defining your patio.

I'm not following which elevation you're asking for about the fence and back of patio. The back of the patio is actually to the right (which is the side of the house) and extends out to the left.

Where I'm taking the picture from would actually have a path. Here is a {{gwi:20594}} from above. The blue arrow is where I was standing/facing for that picture.

And I'm building the patio out of these pavers.

Okay I think Ive got the orientation, but regardless.

It all still makes sense. I would install a rain garden that borders the whole left side (L side in pic, furthest from home in drawing) of the patio and have it drain from both patio and lawn(?) into there, essentially relocating the swale to the outside perimeter of your 19' patio.

The pavers are nice, good choice. Across the distance of your entire patio you will be able to lose the 4" to drain into the rain garden no problem.

When you say "you will be able to lose the 4" to drain into the rain garden"...are you saying I can lower my rise to only 4 inches instead of ~5? I think I'm just reading what you wrote incorrectly.

No sorry, I think I was mistaken. For some reason I was thinking the swale was 4" below grade when as you state its actually only ~2". This complicates it as you wont be able to relocate the swale to the far end of the patio and retain proper drainage (+ - 1"/4') across the 19' of patio as I had mentioned.

In light of this, if you don't want to compromise your patio space I think you need to install a drain near the centre of your patio and redirect the swale to the left side of the patio. The drain will allow you to keep the patio perimeter above the unchanged swale gradient. That option however is conditional on 1) the ability to redirect the swale to the far left side of the patio, as I assume its source is outside of your control and thus can not be completely replaced by said drain (this may require you to modify the patio shape you have designed to allow for the swale to contour it). And 2) that you have somewhere to run your drain to, i.e down toward the street.

you did say though,
"That swale carry's water towards you in the picture...though the way our property is setup, would could technically carry the water either toward or away."
Perhaps this means the swale can be leveled to a lower gradient and allow for what I was initially saying about relocating it and working with 4" slope on patio (4" across 19' is cheating but is not completely unacceptable).

Or if you can gain 2" against the house without interfering with siding as mentioned by a poster above then you will have your patio elevation and be able to relocate the swale.

sorry this advice is based on limited info and a picture, I hope its helpful nonetheless.

Since you are about to spend a lot of money on hardscape, I would strongly suggest you map your entire property to see all the options for making your drainage better. Get out your lot survey and begin drawing a base map. This is what you should do.

Of course that's not what you will do. So, on the limited info given, I assume from text and photos that there is no present drainage problem. This leads me to believe that there is at least a 2% cross slope to your backyard carrying the water toward where the photo was taken. A grading plan can be done to mimic the present one. Use two intersecting planes to do this.

{{gwi:20596}}

In the graphic above, the intersection is shown by the green line. The slope adjoining the house is selected to be 3/8 inch per foot and the other side slope 1/4 inch per foot to best fit the patio shape. A drop of 1/2 inch is made at the house foundation. basic flow over the patio is shown by arrows and should exit in a location that will match the current drainage scheme.

@pls8xx: Thanks for the graphic. I finally (I think) got all of the grading worked out and your graphic was a huge help!