Sliced bread - Help

Okay, this might seem like a pretty dumb question but ... the bread I use (Sainsbury, Taste the Difference Multi-seeded) gives a calory rating of 111 calories per slice. So, here's the dumb part... Thick or thinly sliced? What's the weight of the bread? Is this based on the thickness of the bread when you get it sliced in-store (and it's VERY thin!) or if you cut it yourself, which tends to be a bit thicker. The weight of the in-store slice is between 35 and 55 gm - it's never the same! Any advice would be greatly appreciated.