B5 paper size

ISO B5 measures 176 × 250 mm (6.93 × 9.84 in). The Japanese JIS B5, used for most “B5” notebooks, is slightly larger at 182 × 257 mm (7.17 × 10.12 in).

B5
Millimetres	176 × 250 mm
Centimetres	17.6 × 25 cm
Inches	6.93 × 9.84 in
PDF points (1/72 in)	498.9 × 708.66 pt
Pixels at 72 dpi	499 × 709 px
Pixels at 150 dpi	1039 × 1476 px
Pixels at 300 dpi	2079 × 2953 px

Drawn to the same scale.

B5 next to its neighbours
Size	mm	inches	Difference from B5
B4	250 × 353	9.84 × 13.9	Twice the area
B5	176 × 250	6.93 × 9.84	—
B6	125 × 176	4.92 × 6.93	Half the area
US Letter	215.9 × 279.4	8.5 × 11	+39.9 mm wide, +29.4 mm tall

JIS B5
Millimetres	182 × 257 mm
Centimetres	18.2 × 25.7 cm
Inches	7.17 × 10.12 in
PDF points (1/72 in)	515.91 × 728.5 pt
Pixels at 72 dpi	516 × 729 px
Pixels at 150 dpi	1075 × 1518 px
Pixels at 300 dpi	2150 × 3035 px

What B5 is used for

Notebooks and school exercise books (JIS B5)
Books and journals
Envelopes for A5 and B5 documents

B5 vs A4 and A5

B5 sits between A5 and A4: 34 mm narrower and 47 mm shorter than A4 (ISO B5).

Questions

Is a B5 notebook ISO or JIS?

Usually JIS B5 (182 × 257 mm), because the notebook industry follows Japanese sizes. Check the package dimensions.

How big is B5 in pixels?

ISO B5 is 2079 × 2953 px at 300 dpi; JIS B5 is 2150 × 3035 px.