How to read an EV charging tariff without getting caught out
Per-unit rates, idle fees, tax and connector surcharges all sit behind one headline number. Here is how to work out what a session will actually cost.
Most charging tariffs are quoted as a single per-kWh figure. That number is honest, but it is rarely the whole bill. Four things sit around it, and knowing them turns a guess into arithmetic you can do in your head before you plug in.
The per-unit rate is energy, not time
You are billed for energy delivered into the battery, measured in kilowatt-hours. A 40 kWh battery charged from 20% to 80% takes about 24 kWh. At ₹19.50 per unit that is ₹468 before tax, whether the bay delivered it in twenty minutes or two hours.
This matters because a slower bay does not mean a cheaper session. It means a longer one for the same energy — which is why AC destination bays are usually priced lower per unit than DC.
Tax is added on top
Public charging in India attracts GST on the service. Quoted rates are usually pre-tax, so add the applicable percentage. On our network the invoice always shows the split, so you can see exactly what went to energy and what went to tax.
Idle fees exist for a reason
Some hub sites charge for time spent occupying a bay after the session ends. It reads as unfair until you have waited behind a car that finished forty minutes ago. Where an idle fee applies it is displayed on the station page before you start, and the app warns you when your session completes.
Connector type can change the rate
A 180 kW liquid-cooled dispenser costs far more to install and run than a 7.4 kW wall box. Networks price that difference in. Filter for the slowest bay that still fits your schedule and you will usually pay less per unit.
A worked example
Say you drive a car with a 45 kWh pack, arrive at 25% and want 85%. That is 27 kWh. On a 60 kW fast bay at ₹18.50 per unit, the energy is ₹499.50, tax at 18% adds ₹89.91, and the session takes roughly 35 minutes. Total: about ₹590 for around 250 km of range — roughly a third of what the same distance costs in a petrol hatchback.
Run that calculation once and you stop worrying about tariffs. The numbers are small and the maths is simple.