What paper stock works best for birthday invitations?

Birthday invitations travel through the mail and sit on fridges and mantels, so pick a stock that stays flat and feels sturdy.

• 14pt or 16pt cardstock is the everyday sweet spot. It holds its shape and resists bending in envelopes.
• Milestone or formal birthdays earn a heavier stock with a smooth or soft-touch finish that adds a premium, hefty feel guests notice right away.
• Casual kids parties pair well with a glossy finish that makes bright, playful colors stand out.