Brand vs brand

Wonder Nation vs Little Sleepies sizes

Of Wonder Nation's 11 baby and toddler sizes, 5 line up closely with a Little Sleepies size, 5 are partial matches, and 1 has no clean match. Both charts list weight and height, so the comparison uses both.

Closest pairs: Wonder Nation Preemie = Little Sleepies Preemie, Wonder Nation Newborn = Little Sleepies Newborn, Wonder Nation 0-3M = Little Sleepies 0-3M, Wonder Nation 3-6M = Little Sleepies 3-6M.

Watch the labels: Wonder Nation 0-3M is closer to Little Sleepies 0-3M than to Little Sleepies' own 0-3M; Wonder Nation 3-6M is closer to Little Sleepies 3-6M than to Little Sleepies' own 3-6M; Wonder Nation 2T is closer to Little Sleepies 18-24M than to Little Sleepies' own 2T.

Wonder Nation Runs smallLittle Sleepies True to size

Based on published size charts compared with other brands.

Size by size, on one scale

Each block is one size, placed where the brand's chart puts it. Blocks that sit above each other fit the same baby.

Weight (lb)

Wonder Nation

Preemie: up to 5 lb
Newborn: 5.5 to 7.5 lb
0-3M: 6.5 to 12 lb
3-6M: 12.5 to 16 lb
6-9M: 16.5 to 19 lb
12M: 19.5 to 22 lb
18M: 22.5 to 26 lb
24M: 26.5 to 30 lb
2T: 26.5 to 30 lb
3T: 30.5 to 34 lb
4T: 34.5 to 38 lb

Little Sleepies

Preemie: up to 5 lb
Newborn: 5 to 8 lb
0-3M: 8 to 12 lb
3-6M: 12 to 17 lb
6-12M: 17 to 23 lb
12-18M: 23 to 26 lb
18-24M: 26 to 30 lb
2T: 29 to 31 lb
3T: 31 to 35 lb
4T: 35 to 39 lb

Height (in)

Wonder Nation

Preemie: up to 17 in
Newborn: 17.5 to 21 in
0-3M: 20.5 to 23 in
3-6M: 23.5 to 26 in
6-9M: 26.5 to 27.5 in
12M: 28 to 29.5 in
18M: 30 to 31.5 in
24M: 32 to 33.5 in
2T: 32 to 33.5 in
3T: 34 to 37.5 in
4T: 38 to 41.5 in

Little Sleepies

Preemie: up to 18 in
Newborn: 18 to 21 in
0-3M: 21 to 23 in
3-6M: 23 to 27 in
6-12M: 27 to 31 in
12-18M: 31 to 33 in
18-24M: 33 to 34.5 in
2T: 33 to 36 in
3T: 36 to 39 in
4T: 39 to 42 in

Wonder Nation size to Little Sleepies size

Wonder Nation	Closest Little Sleepies	Match	Weight: Wonder Nation / Little Sleepies	Height: Wonder Nation / Little Sleepies
Preemie	Preemie	Close match	up to 5 lb / up to 5 lb	up to 17 in / up to 18 in
Newborn	Newborn	Close match	5.5 to 7.5 lb / 5 to 8 lb	17.5 to 21 in / 18 to 21 in
0-3M	0-3M	Close match	6.5 to 12 lb / 8 to 12 lb	20.5 to 23 in / 21 to 23 in
3-6M	3-6M	Close match	12.5 to 16 lb / 12 to 17 lb	23.5 to 26 in / 23 to 27 in
6-9M	6-12M	No clean match	16.5 to 19 lb / 17 to 23 lb	26.5 to 27.5 in / 27 to 31 in
12M	6-12M	Partial	19.5 to 22 lb / 17 to 23 lb	28 to 29.5 in / 27 to 31 in
18M	12-18M	Partial	22.5 to 26 lb / 23 to 26 lb	30 to 31.5 in / 31 to 33 in
24M	18-24M	Partial	26.5 to 30 lb / 26 to 30 lb	32 to 33.5 in / 33 to 34.5 in
2T	18-24M	Partial	26.5 to 30 lb / 26 to 30 lb	32 to 33.5 in / 33 to 34.5 in
3T	3T	Partial	30.5 to 34 lb / 31 to 35 lb	34 to 37.5 in / 36 to 39 in
4T	4T	Close match	34.5 to 38 lb / 35 to 39 lb	38 to 41.5 in / 39 to 42 in

Little Sleepies size to Wonder Nation size

Little Sleepies	Closest Wonder Nation	Match	Weight: Little Sleepies / Wonder Nation	Height: Little Sleepies / Wonder Nation
Preemie	Preemie	Close match	up to 5 lb / up to 5 lb	up to 18 in / up to 17 in
Newborn	Newborn	Close match	5 to 8 lb / 5.5 to 7.5 lb	18 to 21 in / 17.5 to 21 in
0-3M	0-3M	Close match	8 to 12 lb / 6.5 to 12 lb	21 to 23 in / 20.5 to 23 in
3-6M	3-6M	Close match	12 to 17 lb / 12.5 to 16 lb	23 to 27 in / 23.5 to 26 in
6-12M	12M	Partial	17 to 23 lb / 19.5 to 22 lb	27 to 31 in / 28 to 29.5 in
12-18M	18M	Partial	23 to 26 lb / 22.5 to 26 lb	31 to 33 in / 30 to 31.5 in
18-24M	24M	Partial	26 to 30 lb / 26.5 to 30 lb	33 to 34.5 in / 32 to 33.5 in
2T	3T	Partial	29 to 31 lb / 30.5 to 34 lb	33 to 36 in / 34 to 37.5 in
3T	3T	Partial	31 to 35 lb / 30.5 to 34 lb	36 to 39 in / 34 to 37.5 in
4T	4T	Close match	35 to 39 lb / 34.5 to 38 lb	39 to 42 in / 38 to 41.5 in

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Size

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Every Wonder Nation size in Little Sleepies

Close match

Wonder Nation Preemie lines up closely with Little Sleepies Preemie.

Weight (lb)

Wonder Nation Preemie up to 5 lb

Little Sleepies Preemie up to 5 lb

Height (in)

Wonder Nation Preemie up to 17 in

Little Sleepies Preemie up to 18 in

The shaded column is the Wonder Nation range. Bars show what each brand publishes for the size.

Based on published size charts. Wonder Nation chart and Little Sleepies chart.

More comparisons

Charts retrieved October 4, 2026 (Wonder Nation) and October 4, 2026 (Little Sleepies). Sources are listed on each brand page. This site is not affiliated with either brand.