Worked example
A 30 kWh battery with a 200 km full-charge range costs about ₹385.00 to fully charge in Tamil Nadu — roughly ₹1.93/km.
Calculate your charging cost
EV Charging Cost Calculator
What a full home charge costs
Cost to fully charge
₹325.00
≈ ₹1.63/km
- Units needed
- 33.33
- Billed at (top slab)
- ₹9.75/unit
Assumes 90% charging efficiency (some energy is lost as heat during AC charging) and prices units at your DISCOM's top tariff slab, since home charging adds to your existing consumption.
How This Is Calculated
The cost comes from your battery capacity, a charging-efficiency loss, and your DISCOM's real tariff:
- Units actually drawn from the grid — battery capacity (kWh) ÷ 90% charging efficiency — you draw more units from the wall than the battery actually stores, because some energy is lost as heat during AC-to-DC conversion inside the car's onboard charger.
- Cost to fully charge — units drawn × your DISCOM's top-slab rate — home charging adds substantially to your existing household consumption, so it's priced like any other large appliance, at your highest marginal tariff slab.
- Cost per km — cost to fully charge ÷ your EV's full-charge range — this is the number that makes a direct, apples-to-apples comparison with a petrol, diesel or CNG vehicle's cost per km meaningful.
Takeaway: the 10% efficiency loss means a 30 kWh battery actually draws about 33.3 units from the grid to fully charge — always budget for the units drawn, not just the battery's rated capacity.
Why Your Real Charging Cost May Differ
- Charger type and speed — this calculator models typical home AC (Level 1/2) charging efficiency — DC fast charging has different loss characteristics and is usually billed at a separate, higher public-charger rate rather than your home tariff.
- Battery age and temperature — a battery's usable capacity and charging efficiency can both decline somewhat with age, and charging in very hot or cold weather is generally less efficient than in moderate conditions — real-world consumption can drift from the spec-sheet figures over a vehicle's life.
- Your DISCOM's tariff structure — if your state or DISCOM uses time-of-day (ToD) tariffs, charging during an off-peak window can cost meaningfully less per unit than the top-slab daytime rate this calculator assumes by default.
- Partial charging habits — topping up from 40% to 80% daily draws fewer units per session than always charging from empty to full — your actual monthly cost depends on your real charging pattern, not just the full-charge figure shown here.
Ways to Reduce Your EV Charging Cost
- Check for a time-of-day tariff — some DISCOMs offer a lower rate during specific off-peak hours — scheduling charging overnight or during that window, if your state offers it, can meaningfully cut the top-slab cost this calculator assumes.
- Avoid unnecessary full-to-empty cycles — charging little and often, rather than always draining to empty first, doesn't change your cost per unit but keeps each individual charging session smaller and easier to schedule around off-peak windows.
- Pair home charging with rooftop solar — daytime solar generation can offset a meaningful share of home EV charging if your charging schedule overlaps with sunlight hours — see our Solar ROI Calculator to estimate whether that combination pays off for your usage.
- Compare public fast-charger pricing before relying on it — public DC fast chargers typically charge a per-unit rate above residential tariffs, sometimes with an added service fee — home charging is usually the cheaper default wherever it's practical.
EV vs Petrol vs Diesel vs CNG — cost per km
EV cost uses your real DISCOM tariff from above; enter your own fuel prices and mileage for a genuine like-for-like comparison.
EV cost is priced at your real DISCOM tariff (from the calculator above). Enter today's local fuel prices and your vehicle's real mileage for the rest — these vary too much by city and vehicle to assume.
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Frequently asked questions
Why is home EV charging priced at my top tariff slab?
Charging an EV at home adds substantially to your existing consumption, so — like an AC — its units fall in your highest, most expensive tariff slab rather than a blended average rate.
Why does the calculator assume 90% charging efficiency?
AC home charging loses some energy as heat during conversion inside the car's onboard charger. About 90% efficiency is a commonly cited figure for typical home (Level 1/2 AC) charging — DC fast charging has different loss characteristics.
How do I find my EV's battery capacity and range?
Both are published in your vehicle's spec sheet — battery capacity in kWh (usable capacity, not always the same as the marketed "gross" figure) and the certified or real-world range in km.
Is home charging cheaper than a public fast charger?
Usually yes — public DC fast chargers typically charge a per-unit rate well above residential tariffs, plus sometimes a service fee, whereas home charging uses your normal household tariff.
Is an EV actually cheaper to run than a petrol or diesel car?
Almost always yes on a per-km basis, sometimes by a wide margin — use the comparison tool below with your real local fuel prices and your specific vehicles' mileage to see your own numbers rather than a generic claim.
Why does the comparison tool ask for my own petrol/diesel/CNG price and mileage?
Fuel prices vary by city and change daily, and vehicle mileage varies by model and driving conditions — using your own real numbers gives an honest comparison instead of a generic assumed figure that might not match your situation.
Does EV charging cost change with electricity tariff hikes the same way petrol prices change?
Yes — like any electricity use, EV charging cost moves with your DISCOM's tariff. Historically, electricity tariffs have changed less frequently and less sharply than daily-revised fuel prices, but there's no guarantee that continues indefinitely.
Does charging speed (slow vs fast home charging) change the cost?
Not meaningfully for the ₹ total — you're paying for the same units (kWh) delivered either way. Faster home charging (higher amperage) mainly affects how long it takes, not how much it costs, though very high loads could theoretically push some usage into a different tariff period if your DISCOM uses time-of-day rates.