Boy Measurements 5-18 yrs

From various websites compiled as help for writers of boy erotic stories.

Age	HEIGHT from 5th-95th percentile	WEIGHT from 5th-95th percentile	PENIS SIZE length - circumference
Age	HEIGHT from 5th-95th percentile	WEIGHT from 5th-95th percentile	flaccid	erect	circ
5	1.02 - 1.17 m / 3'4" - 3'10"	15 - 23 kg / 33½ - 51 lbs.	2½ - 5 cm / 1 - 2"	5 - 10 cm / 2 - 4"	6½ cm / 2½"
6	1.08 - 1.23 m / 3'7" - 4'	19 - 26 kg / 41½ - 58 lbs.
7	1.13 - 1.30 m / 3'8" - 4'3"	18½ - 30 kg / 41 - 66 lbs.
8	1.18 - 1.36 m / 3'10" - 4'6"	20½ - 34½ kg / 45 - 76 lbs.
9	1.23 - 1.42 m / 4' - 4'8"	22 - 39½ kg / 49 - 87 lbs.
10	1.28 - 1.48 m / 4'2" - 4'10"	24½ - 45 kg / 53½ - 100 lbs.
11	1.33 - 1.55 m / 4'4" - 5'1"	27 - 51½ kg / 59 - 114 lbs.		7½ - 9½ cm / 3 - 3.8"
12	1.38 - 1.62 m / 4'6" - 5'4"	30 - 58 kg / 66 - 128 lbs.		7½ - 9½ cm / 3 - 3.8"
13	1.43 - 1.70 m / 4'8" - 5'7"	33½ - 65 kg / 74 - 143 lbs.	4 - 5 cm / 1½ - 2"	12½ cm / 5"	7½ cm / 3"
14	1.49 - 1.77 m / 4'11" - 5'10"	38 - 72 kg / 84 - 159 lbs.	5 - 8 cm / 2 - 3"	13½ cm / 5½"	8½ cm / 3½"
15	1.55 - 1.82 m / 5'1" - 6'	43 - 79 kg / 95 - 174 lbs.	5 - 10 cm / 2 - 4"	14 cm / 5½"	10 cm / 4"
16	1.61 - 1.85 m / 5'3" - 6'1"	47½ - 85½ kg / 105 - 189 lbs.	6 - 10 cm / 2½ - 4"	14½ cm / 5¾"	10½ cm / 4¼"
17	1.65 - 1.87 m / 5'5" - 6'2"	51½ - 91½ kg / 114 - 201 lbs.	7½ - 10 cm / 3 - 4"	14¾ cm / 6"	11 cm / 4½"
18	1.66 - 1.88 m / 5'5" - 6'2"	54 - 96 kg / 119 - 211 lbs.	9 - 10 cm / 3½ - 4"	14¾ cm / 6"	11¾ cm / 4½"
adult	-	-	9 - 10 cm / 3½ - 4"	14 - 16 cm / 5½ - 6½"	12½ cm / 5"

Puberty and ejaculation

The average age to begin puberty is around 13-years-old. However, a boy may start to fully develop at a young age of 10 or 12, but also a boy may not develop until early teens. Boys would first ejaculate between 10-14.

Tanner scale of physical development of balls and penis

Tanner I: testicular volume less than 1.5 ml; small penis of 3 cm or less (prepubertal) (typically age nine and younger)
Tanner II: testicular volume between 1.6 and 6 ml; skin on scrotum thins, reddens and enlarges; penis length unchanged (9–11)
Tanner III: testicular volume between 6 and 12 ml; scrotum enlarges further; penis begins to lengthen to about 6 cm (11–12.5)
Tanner IV: testicular volume between 12 and 20 ml; scrotum enlarges further and darkens; penis increases in length to 10 cm (12.5–14)
Tanner V: testicular volume greater than 20 ml; adult scrotum and penis of 15 cm in length (14+)

Tanner scale of development of pubic hair

Tanner I: no pubic hair at all prepubertal) (typically age 10 and younger)
Tanner II: small amount of long, downy hair with slight pigmentation at the base of the penis and scrotum (10–11.5)
Tanner III: hair becomes more coarse and curly, and begins to extend laterally (11.5–13)
Tanner IV: adult–like hair quality, extending across pubis but sparing medial thighs (13–15)
Tanner V: hair extends to medial surface of the thighs (15+)