Prescriptions for reading glasses increase by 0.25 diopters, such as +1.00, +1.25, +1.50, and so on. However, for simplicity, some diopter charts may increase by 0.50 or by the whole number. Start by trying on reading glasses in the power that your test results yielded. You'll want to test out several pairs that are both weaker and stronger than your test results. Narrow it down to two magnifications — both of which you see well with — and always choose the lower of the two powers.