How long a home EV charger installation takes to pay for itself, based on how much you'd otherwise spend charging in public.
Annual charging energy is estimated from your mileage and efficiency, grossed up for charging losses, then priced at both the "without a home charger" rate (typically public charging) and the "with a home charger" rate (typically an off-peak home tariff). The difference is your annual saving, and the payback period is simply the install cost divided by the monthly saving: Payback (months) = Install cost ÷ (Annual saving ÷ 12).
This doesn't include any grant schemes or discounts that may reduce your install cost, or standing charge differences between tariffs — treat it as a straightforward energy-cost comparison. See home vs public charging for the reasoning behind the default rates, or use the cost calculator for a single-charge breakdown.