Month 4: pureed carrots. Month 5: still drinking 800ml formula. Month 6: confusion. Here is the transition timeline.
I get this question constantly. "I started solids. When do I cut back formula?" The answer is: slowly, and not as much as you think.
Solids at 4-6 months are for exploration, not nutrition. Your baby is learning tastes, textures, and motor skills. The actual calories from a few spoonfuls of puree are tiny. Formula or breast milk remains the primary nutrition source until 12 months.
Here is the typical timeline:
Months 4-6: Start with 1-2 tablespoons of puree once daily. Formula stays the same. Baby might drink slightly less because they are full from the new experience, but do not intentionally reduce.
Months 6-8: Increase to 2-3 meals of solids. Formula might drop from 900ml to 750ml per day. This is normal. The solids are still supplemental.
Months 8-10: 3 meals of solids plus snacks. Formula drops to 600-700ml. Some babies self-wean slightly. Others hold steady. Both are fine.
Months 10-12: Solids are now substantial. Formula drops to 500-600ml. By 12 months, transition to whole milk (or continue formula if preferred).
My twins were typical. Emma dropped formula fast once she discovered food. Jack held onto his bottles like they were life itself. By month 10, Emma was at 500ml and Jack was at 700ml. Both were healthy. Both were eating well.
Do not rush the transition. Formula provides complete nutrition. Solids do not, at first. Let your baby lead. If they want less formula, offer less. If they still want 800ml at month 9, that is fine too.
Use our Formula Calculator with the "older infant" setting. It accounts for reduced formula needs as solids increase.