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Tech OVN

Calculator

EV Charger Sizing Calculator

Which AC EV charger do you actually need — 3.3 kW, or 7.4 kW / 11 kW / 22 kW Type 2? Enter energy per session, dwell time, daily vehicles and your site's charging window, and get a recommended rating and charger count.

Inputs

Result

Recommended charger
3.3 kW AC
Slow AC charge — the Single Socket 3.3 kW, or a Type 2 unit at 3.3 kW, covers overnight home or all-day office parking.
Power required per bay
3.1kW
Working chargers needed
5
Sessions per charger per day
1
Connected load if all run at once
16.5kW
EV-capable bays to provision
5bays
Each charger serves one vehicle for its full dwell time, so chargers needed = vehicles ÷ sessions that fit in the site's charging window. Check the connected load against your sanctioned load — Tech OVN chargers do not do dynamic load balancing. Provisioning extra conduit and DB space now (we assume at least 5% of parking) is cheaper than retrofitting later.

How this works

Charger power is chosen by how much energy a driver needs and how long they'll stay. A typical EV uses 12–15 kWh per 100 km, so a 30 kWh top-up gives ~200 km of range. Delivering 30 kWh in 1 hour means you need a 30 kW DC fast charger; in 4 hours a 7.4 kW AC charger does it; in 10 hours a 3.3 kW single socket is plenty. For a full breakdown of AC and DC charging levels and connector standards, see our guide to the different levels of EV charging.

The second variable is throughput — how many vehicles need to charge per day. Because a charger is occupied for as long as the vehicle is parked, the calculator divides the site's charging window by the dwell time to see how many sessions one charger can serve, then works out the number of working chargers, the connected load, and how many EV-capable bays to provision (conduit + DB space) for future expansion.

For the right hardware, see our EV chargers page. For location-specific deployment guides, see EV charging for hotels, malls, hospitals, commercial properties, and offices.

Frequently asked questions

Divide the energy each vehicle needs by how long it stays. With the calculator's defaults: home (30 kWh over 10 h) and office (25 kWh over 8 h) → 3.3 kW; hotel overnight (40 kWh over 10 h), fleet depot overnight (50 kWh over 8 h) and mall visitors (20 kWh over 3 h) → 7.4 kW Type 2. Go to 11 or 22 kW only when vehicles need more energy in a shorter stay and their onboard chargers can accept it. Under about an hour needs DC fast charging, which we do not make. Higher power costs more and adds to maximum demand — don't oversize just because you can.
Each charger serves one vehicle for as long as that vehicle is parked, so count how many back-to-back sessions fit in the hours your site is in use. Five office cars parked for 8 hours in a 10-hour working day need five chargers; mall visitors staying 3 hours in a 12-hour day can share — four sessions per charger. Separately, provision extra conduit and DB space for future bays; it is far cheaper than retrofitting later.
EV-capable = conduit and DB capacity reserved, no charger yet. EV-ready = conduit + outlet installed, just needs a charger plugged in. Installed = working charger on the bay. Municipal mandates increasingly require a mix of all three in new construction.
When dwell time is under about an hour and drivers need substantial added range per session — typically highway corridors and fleets with quick turnaround. For most other use cases, AC is cheaper and sufficient. Tech OVN manufactures AC chargers only.
Add up the rating of every charger that can run at the same time (the calculator shows this as connected load) and compare it with the spare capacity in your sanctioned load and distribution board. If it does not fit, choose a lower rating per bay (3.3 or 7.4 kW instead of 22 kW) or apply for a load enhancement. Tech OVN chargers do not offer dynamic load balancing, so size the supply for the chargers you install.

Related pages & tools

EV Chargers (Product Range)

All EV chargers we make — 3.3 kW single socket and 3.3–22 kW Type 2, OCPP 1.6J and 2.0.1.

Learn More →

EV Charging Cost Per KM

Calculate your actual cost-per-km at current tariffs and compare with petrol.

Learn More →

EV Charging Metering Solution

Per-charger revenue-grade kWh measurement — needed for any billing scenario.

Learn More →

Single socket 3.3 kW EV charger

Compact 3.3 kW AC charger for homes, offices and housing societies — IP55, OCPP 2.0.1, Class 1 metering. From ₹10,500 + GST.

Learn More →

Type 2 home EV charger

7.4 kW single-phase or 22 kW three-phase Type 2 home charger with built-in energy meter and a home app for scheduling and cost tracking.

Learn More →

Get a quote based on these numbers

Share your site details and we'll come back with a charger recommendation and a quote. (We supply hardware; we don't prepare subsidy BOQs or do site surveys.)

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