Size 100 in baby clothes is a European size that is equivalent to 3T or 4T in the US, depending on the brand. It is meant for a maximum height of around 39.4 inches and will likely fit a toddler weighing between 31 and 38 pounds. However, its important to note that baby clothes sizes can vary between brands, so its always best to check the specific brands size chart before making a purchase. Other size conversions for European baby clothes include:

• Size 60: Equivalent to 3-6 months in the US, meant for a maximum height of 60 centimeters (approximately 23.6 inches) .
• Size 70: Equivalent to 6-9 months or 6-12 months in the US, meant for a maximum height of 27.5 inches.
• Size 80: Equivalent to 18-24 months in the US, meant for a maximum height of about 31.5 inches.
• Size 90: Equivalent to 2T in the US, meant for a toddler who weighs between 26 and 33 pounds or up to a height of 36 inches.

Its also worth noting that some brands may use different sizing systems, such as Japanese sizing. When in doubt, its always best to check the brands size chart or consult with a customer service representative.