Brand vs brand

Wonder Nation vs Primary sizes

Of Wonder Nation's 11 baby and toddler sizes, 2 line up closely with a Primary size, 8 are partial matches, and 1 has no clean match. Both charts list weight and height, so the comparison uses both.

Closest pairs: Wonder Nation 24M = Primary 18-24M, Wonder Nation 2T = Primary 18-24M.

Watch the labels: Wonder Nation Newborn is closer to Primary Newborn than to Primary's own Newborn; Wonder Nation 0-3M is closer to Primary 0-3M than to Primary's own 0-3M; Wonder Nation 3-6M is closer to Primary 3-6M than to Primary's own 3-6M.

Wonder Nation Runs smallPrimary 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

Primary

Newborn: 5.1 to 9 lb
0-3M: 9 to 11.9 lb
3-6M: 11.9 to 15 lb
6-9M: 15 to 18.1 lb
6-12M: 15 to 22 lb
9-12M: 18.1 to 22 lb
12-18M: 22 to 26.9 lb
18-24M: 26.9 to 30 lb
2: 30 to 33.1 lb
3: 33.1 to 35.9 lb
4: 35.9 to 39.9 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

Primary

Newborn: up to 18.1 in
0-3M: 18.1 to 22.8 in
3-6M: 22.8 to 25.2 in
6-9M: 25.2 to 27.2 in
6-12M: 25.2 to 29.1 in
9-12M: 27.2 to 29.1 in
12-18M: 29.1 to 31.1 in
18-24M: 31.1 to 33.1 in
2: 33.1 to 35 in
3: 35 to 38.2 in
4: 38.2 to 40.9 in

Wonder Nation size to Primary size

Wonder Nation	Closest Primary	Match	Weight: Wonder Nation / Primary	Height: Wonder Nation / Primary
Preemie	Newborn	No clean match	up to 5 lb / 5.1 to 9 lb	up to 17 in / up to 18.1 in
Newborn	Newborn	Partial	5.5 to 7.5 lb / 5.1 to 9 lb	17.5 to 21 in / up to 18.1 in
0-3M	0-3M	Partial	6.5 to 12 lb / 9 to 11.9 lb	20.5 to 23 in / 18.1 to 22.8 in
3-6M	3-6M	Partial	12.5 to 16 lb / 11.9 to 15 lb	23.5 to 26 in / 22.8 to 25.2 in
6-9M	6-9M	Partial	16.5 to 19 lb / 15 to 18.1 lb	26.5 to 27.5 in / 25.2 to 27.2 in
12M	9-12M	Partial	19.5 to 22 lb / 18.1 to 22 lb	28 to 29.5 in / 27.2 to 29.1 in
18M	12-18M	Partial	22.5 to 26 lb / 22 to 26.9 lb	30 to 31.5 in / 29.1 to 31.1 in
24M	18-24M	Close match	26.5 to 30 lb / 26.9 to 30 lb	32 to 33.5 in / 31.1 to 33.1 in
2T	18-24M	Close match	26.5 to 30 lb / 26.9 to 30 lb	32 to 33.5 in / 31.1 to 33.1 in
3T	2	Partial	30.5 to 34 lb / 30 to 33.1 lb	34 to 37.5 in / 33.1 to 35 in
4T	4	Partial	34.5 to 38 lb / 35.9 to 39.9 lb	38 to 41.5 in / 38.2 to 40.9 in

Primary size to Wonder Nation size

Primary	Closest Wonder Nation	Match	Weight: Primary / Wonder Nation	Height: Primary / Wonder Nation
Newborn	Newborn	Partial	5.1 to 9 lb / 5.5 to 7.5 lb	up to 18.1 in / 17.5 to 21 in
0-3M	0-3M	Partial	9 to 11.9 lb / 6.5 to 12 lb	18.1 to 22.8 in / 20.5 to 23 in
3-6M	3-6M	Partial	11.9 to 15 lb / 12.5 to 16 lb	22.8 to 25.2 in / 23.5 to 26 in
6-9M	6-9M	Partial	15 to 18.1 lb / 16.5 to 19 lb	25.2 to 27.2 in / 26.5 to 27.5 in
6-12M	12M	Partial	15 to 22 lb / 19.5 to 22 lb	25.2 to 29.1 in / 28 to 29.5 in
9-12M	12M	Partial	18.1 to 22 lb / 19.5 to 22 lb	27.2 to 29.1 in / 28 to 29.5 in
12-18M	18M	Partial	22 to 26.9 lb / 22.5 to 26 lb	29.1 to 31.1 in / 30 to 31.5 in
18-24M	24M	Close match	26.9 to 30 lb / 26.5 to 30 lb	31.1 to 33.1 in / 32 to 33.5 in
2	3T	Partial	30 to 33.1 lb / 30.5 to 34 lb	33.1 to 35 in / 34 to 37.5 in
3	3T	Partial	33.1 to 35.9 lb / 30.5 to 34 lb	35 to 38.2 in / 34 to 37.5 in
4	4T	Partial	35.9 to 39.9 lb / 34.5 to 38 lb	38.2 to 40.9 in / 38 to 41.5 in

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Size

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Every Wonder Nation size in Primary

Close match

Wonder Nation 24M lines up closely with Primary 18-24M.

Weight (lb)

Wonder Nation 24M 26.5 to 30 lb

Primary 12-18M 22 to 26.9 lb

Primary 18-24M 26.9 to 30 lb

Primary 2 30 to 33.1 lb

Height (in)

Wonder Nation 24M 32 to 33.5 in

Primary 12-18M 29.1 to 31.1 in

Primary 18-24M 31.1 to 33.1 in

Primary 2 33.1 to 35 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 Primary chart.

More comparisons

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