B4
B-Series (ISO 216) · 7 specs
Direct Answer
B4 is an ISO 216 standard paper size measuring 250 × 353 mm (9.84 × 13.90 inches) with a surface area of ~0.088 square meters. Sized intermediate between A3 and A4, it is the worldwide standard for printed orchestral sheet music, professional accounting ledgers, and Japanese manga manuscript paper.
Source: ISO 216:2007 / JIS P 0138 (Japanese B4) · Last reviewed Aug 28, 2026
Specs
| Width × Height (Metric) | 250 × 353 mm |
| Width × Height (Imperial) | 9.84 × 13.90 in |
| Nominal Surface Area | 0.088 m² (88,250 mm²) |
| Geometric Mean Origin | Geometric mean of A3 (297×420 mm) and A4 (210×297 mm) |
| Japanese JIS B4 Distinction | JIS B4 is slightly larger (257 × 364 mm) due to historical Mino paper origins |
| Weight of 80 gsm Sheet | 7.06 grams |
| Primary Applications | Classical sheet music scores, accounting ledgers, Japanese manga manuscripts |
The Music Score Standard
Standard A4 paper is slightly too narrow to accommodate dense orchestral staves and multi-instrument choral scores, while A3 is too wide to rest on piano music stands. B4 (250 × 353 mm) provides the optimum width and height for legible stave spacing without requiring frequent page turns.
ISO B4 vs Japanese JIS B4
In Japan, paper sizing uses JIS B4 (257 × 364 mm), which is approximately 1.15× larger than ISO B4 because the Japanese Industrial Standard based its B-series on historical Edo-period Mino master sheets (1.5× A4) rather than the international geometric mean.