1. Football (Soccer) - FIFA

Size 5 (Standard): Circumference: 68–70 cm (27–28 in). Weight: 410–450 g (14–16 oz). Pressure: 0.6 – 1.1 bar (8.7 – 16.0 psi) at sea level.
Size 4 (Youth): Circumference: 63.5–66 cm (25–26 in). Used for players aged 8-12.
Size 3 (Junior): Circumference: 58.5–61 cm (23–24 in). Used for young children.
Note: The official match ball for tournaments like the World Cup must bear the "FIFA QUALITY PRO" mark, indicating it has passed the most stringent tests.

2. Basketball - FIBA

Size 7 (Men's Official): Circumference: 749–780 mm (29.5–30.7 in). Weight: 567–650 g (20–23 oz).
Size 6 (Women's Official): Circumference: 724–737 mm (28.5–29 in). Weight: 510–567 g (18–20 oz).
Size 5 (Youth): Circumference: 690–710 mm (27–28 in). Weight: 470–500 g (16.5–17.6 oz).
The recommended inflation pressure is typically 7 to 9 psi.

3. Volleyball - FIVB

Circumference: 65–67 cm (25.6–26.4 in).
Weight: 260–280 g (9.2–9.9 oz).
Pressure: 0.30–0.325 kg/cm² (4.26–4.61 psi).
Indoor and beach volleyballs have different material and construction standards.

4. Tennis - ITF

Diameter: 6.54–6.86 cm (2.57–2.70 in).
Weight: 56.0–59.4 g (1.975–2.095 oz).
Rebound: 135–147 cm (53–58 in) when dropped from 254 cm (100 in).
Tennis balls are also classified by type (Type 1, 2, 3, 4) for different court speeds and altitudes.

5. Rugby - World Rugby

Size 5 (Adult): Length: 28–30 cm (11–12 in). Circumference (width): 58–62 cm (23–24 in). Weight: 410–460 g (14.5–16.2 oz).
Size 4 (Women's & Youth): Slightly smaller and lighter.
Pressure: 0.67–0.70 bar (9.5–10.0 psi).

6. American Football - NFL / IFAF

Official (Pro): Length: ~11 in (28 cm). Long Circumference: ~28 in (71 cm). Short Circumference: ~21 in (53 cm). Weight: 14–15 oz (397–425 g).
College & High School: Slightly different dimensions, with white stripes on the ends for college.
Pressure: 12.5–13.5 psi.

7. Cricket - ICC

Men's: Weight: 155.9–163.0 g (5.5–5.75 oz). Circumference: 22.4–22.9 cm (8.81–9.00 in).
Women's: Weight: 140–151 g (4.94–5.31 oz). Circumference: 21.0–22.5 cm (8.25–8.86 in).
Junior: Comes in multiple sizes (e.g., Size 4, Size 3).

8. Baseball - MLB / IBAF

Circumference: 9.00–9.25 in (22.86–23.50 cm).
Weight: 5.00–5.25 oz (141.75–148.83 g).
The ball has a cork and rubber core, wound in yarn, and covered in leather.

9. Golf Ball - USGA & R&A

Diameter: Not less than 1.680 in (42.67 mm). Weight: Not greater than 1.620 oz (45.93 g).
The rules also strictly govern symmetry, initial velocity, and overall distance.

Key Points to Remember:
① Tolerance Ranges: All standards include a small tolerance range for size and weight to account for manufacturing variances and environmental conditions (like altitude and humidity).
② Age & Gender Categories: Most sports have different official sizes for men, women, and various youth age groups.
③ Official Approval: For professional and international matches, balls must bear specific approval logos (e.g., FIFA Quality Pro, FIBA Approved, IBF Approved).