In general, for daily use products or oil blends containing Essential Oil, it's advised to add 0.5 to 1% of Essential Oil in total (So if adding more than 1 Essential Oi,l you need to split the quantity to make it max 1% in total) Foran oil blend specifically destined for stronger scalp treatment that would be used less frequently, you can consider using 1 to 3% of Essential Oil in the blend. Quick drop calculator: For 15ml of carrier oil 0.5% → 2 drops 1 % → 4–5 drops 2 % → 9–10 drops 3 % → 13–15 drops