18" is minimal for the seat depth, but if you are adding a back cushion you need more than 18". I'd say 21" and a decent cushion.

You can get custom cushions made check Esty.

I decided to go with scatter cushions instead of an upholstered back. The benches are 18" deep, and the seat cushions were custom made. The colours of the scatter cushions don't look quite right in a cropped photo, but I like the look in the whole kitchen.

Thank you for your feedback P Banos, I'll look at Etsy for custom cushions.

Toronto Veterinarian, thank you for the photo! It is very helpful because our benches also won't have a back.

Sophie Wheeler, thanks for the information. We are "faking" benches with kitchen cabinets. So they will only have lowers, they will have no back. So I need to figure out the depth and then see what kind of custom cushions I can buy or pillow ensemble that will make the whole thing more comfortable.

Why no back? It’s easy enough to construct. It’s just an angled plywood box. And it improved functionality and comfort immensely. You can even construct it as a drop down or lift up “door” for hidden storage. Great place for firearms or valuables. Or chocolate.

Firearms and Chocolate = Romantic Dining?

You are faking, and using old cabinetry. I'd say forget it and start anew, as Sophie stated above.. Not worth the time/expense in jiggle/reconfigure of old cabinetry. You must allow for seat cushioning, so build no higher than 17 inches, ( 2 inch firm foam cushioning added post finish)) and allow a seat depth of no less than 22 for pillows or back cushioning.

My benches are 24" and against windows, so I have toss pillows but not backs. It's like sitting on an open bench. Fine for a few minutes but not for eating a nice dinner. There's no back support.

Our bench cushions are 21.5 in. deep and 3in. thick. The back slab cushion is 4.5in. deep at the base, sloping to 1.5in. at top. We built a sloping back too. Lots of games have been played around the table with no complaints. Toss cushions are great for extra support, naps or lounging.

Forgot to mention that cushions were made by a local foam shop. They do such work all the time for RV or boat owners.

The mistake I made when I spec'd my custom booth:
Defining the ideal seat cushion depth without adding the depth of the back cushion.
"Total depth" + "seated depth" are 2 different measurements.

Everyone still loves it, it's automatically where people gravitate, but it would be more comfy with +3" more depth...

" We are "faking" benches with kitchen cabinets. So they will only have lowers, they will have no back"

Are these benches for an eating booth, or benches against a wall? My benches are along a corner - one side against a wall, one side against a window - and they form corner seating for my table. There are chairs for the other 2 sides of the table.

Oh wow, the last time I responded I didn't notice all these responses in the thread. These are benches against a wall with windows (the benches wrap around a corner and are for table seating), and the windows are about 36" from the ground. I wonder if this means we won't have space for back cushions? Does anyone know?

If there is no space for back cushions then I guess I will make them 18" wide and toss a few pillows on there hoping my kids will be comfortable enough to eat meals there.

If there IS space for back cushions then I'll make them 24" wide and get slanted thick foam backs as described above.

Thanks!