To make 15ml of the chamomile extract, you'll want to do a little math and adjust the recipe accordingly. For example, 15ml is 3% of the 500ml of water recommended in the formulation recipe. To ensure the same ratio, you'll also use 3% of the 100g of flowers recommended, which equates to 3g of flowers. Therefore, 15ml water + 3g flowers = 15ml chamomile extract.