There is no "average". It would depend your total space, and number of slabs. The photo and large space is deceiving. It's probably nine inches to a foot. You are looking at a space that was designed. To the inch.

Deck boards are typically 5.5", so the gaps look to be roughly 4-6", which is pretty typical. I generally do a roughly 4" gap, as that gives plenty of room for the gravel or groundcover between the slabs while making it walkable. The smaller the slab, though, the tighter the gap or else you look like the ministry of silly walks when you go down the path.

Shoot me. Rev Gardens would know : ) Alas, still a proportion thing. I should get busy baking the cookies.........also not my major expertise lol

LOL so true in many things .

I suspect those are not 5.5" deck boards. My guess for the gaps between concrete: 3"

Nah. The steps way at the top of the pic look to be typical 12-14" steps, which checks out with the deck boards @ 1x6. They may look smaller against the foreground steps but if you look at the proportions of rise over run, I'd wager those are more like 16-18" treads.

After another look and reconsidering, revising my guess to 4" gap.

"spacing between poured concrete slabs"

I don't believe the squares are poured in place. They are simply concrete pavers that have been set and backfilled with gravel.

We have a local concrete specialities yard that sells many size squares in a variety of colors.

These pavers for the driveway are likely thicker to support the weight of a vehicle.

I'm betting those are precast. Much better product than placed on site. You're not getting factory color, consistency, size, and quality from Johnny's Pools 'N Concrete.

There is a limit on sizing for precast pavers. Generally 24"x24" is about as large as you will find as transport, moving onsite and even installing becomes precarious or problematic if larger than that. The pavers in the photos might very well be poured in place....it is a bit tricky to judge an accurate scale from just the photo. But the two pavers forming a landing and turning the corner at the top of the stairs certainly look larger than 2 foot square!!

I'd also judge the spacing gap to be 4 inches.....between 3-4 inches is pretty standard for that size paver.

Agree w/ gardengal that those pavers at the top of the steps are monsters. When I worked in California we did several backyards with poured in place pads like this. No, you don't want to hire some random Chuck in a truck for this, but any quality concrete finisher could do this.

The spacing can vary depending on what material you plan to use in between.

If you're planning to put chairs on this surface, consider the legs not sitting completely on the hard surface. 1 chair leg may be in the space making an uneven, rocking situation.

While the idea is nice looking, it's not practical.

As Mystic Pools said, it can vary depending on the material you plan to use in between. It also can vary depending on the size of the pavers, what you plan on using the space for (again, as Mystic Pools mentioned, furniture like chairs or tables can get caught between the pavers), also the aesthetic of the space itself and what your design tastes are.

If you like this specific design, one option is you can measure the ratio of paver to space and up that to the scale of your space.

Does anyone carry spacers or a grid to establish a uniform 3-4 inch space around the pavers (and help keep them form moving )?