Compare the cost of organic and conventional produce.
The organic premium is normally quoted as a percentage over conventional, and it varies enormously by product — often 20 to 40 percent for hardy vegetables and root crops, but well over 100 percent for soft fruit and salad leaves where organic yields are lowest and losses highest. What actually determines your spend is the blended figure: buying half your produce organic does not cost half the full premium if the organic half happens to be the expensive items. Modelling the share you buy organic and reporting the blended cost per kilogram makes the decision a dial rather than a switch.
Premium
Premium % = (organic price - conventional price) / conventional price x 100
Blended basket
Blended per kg = (organic kg x organic price + conventional kg x conventional price) / total kg
It tracks how much harder the crop is to grow without synthetic inputs. Hardy roots and brassicas manage with modest yield losses, so the premium is small. Soft fruit and leafy salads suffer high pest and disease losses organically, so premiums above 100 percent are common.
Prioritise the produce you eat unpeeled and in quantity — berries, leafy greens, apples — where residue exposure is highest relative to spend. Items with thick inedible skins such as bananas, avocados and citrus give the least benefit per pound of premium paid.