What TOG rating do I need for my baby's sleep sack?

TOG measures thermal insulation. As a rough guide reviewers across the candidate set converge on: 0.5 TOG for rooms 74°F and warmer, 1.0 TOG for 69–73°F, 1.5 TOG for the mid-60s, and 2.5 TOG for cold rooms below 65°F. Most pediatric safe-sleep guidance recommends dressing baby in lighter layers underneath in summer and a long-sleeve onesie or footed pajamas underneath in winter.