11 calculators for planning a home charger install
Start here
Run them in this order: panel capacity first, because it is the only constraint you cannot buy your way around, then charging speed, then the circuit, then cost. A 48 amp charger needs a 60 amp breaker and delivers 11.5 kW; a 40 amp charger needs a 50 amp breaker and delivers 9.6 kW.
Where the numbers usually land
Where the numbers usually land
EMPORIA
Emporia Level 2 EV Charger, 48A J1772
$449.00
Nearly every calculator on this page converges on the same recommendation for a household that owns a car with an 11.5 kW onboard charger and a panel with room: a 48 amp hardwired station on a 60 amp circuit. This is that unit at roughly half the price of the premium brands.
- Output
- 11.5 kW
- Continuous
- 48 A
- Circuit
- 60 A
- Cable
- 25 ft
- Install
- Hardwired
- Connector
- J1772
Paid link. Price shown when researched.
Run them in this order
The sequence matters more than any individual calculator, because each stage narrows what the next one has to consider. Working out charge times before you know whether the panel can carry a circuit is how people end up with a shopping list they cannot install.
- Stage 1
Find out whether the project is even possible
Panel capacity is the only constraint you cannot solve with a different purchase, so it goes first. It is also the difference between a 1,600 dollar job and a 9,000 dollar one, which makes it the single most expensive question to answer late.
- Stage 2
Work out how much charging you actually need
Not how fast you could charge, but how much you have to replace in the hours the car is parked. Most people need far less than they assume, and finding that out here saves money at every later stage.
- Stage 3
Size the circuit
The continuous load rule, the conductor, and the distance. These three run together, because on a long run the distance rather than the amperage decides the wire.
- Stage 4
Price the job before you get quotes
Knowing the expected range turns a quote from a number you accept into a number you can question. On most installs the labour is the largest line, so this is where the total is decided.
- Stage 5
Work out what it costs to run, and what it saves
The running cost is small and the tariff you are on moves it more than anything about the hardware. This is also where you find out whether the install pays for itself and how quickly.
The one table every calculator refers back to
EV charging is a continuous load, so the circuit is sized at 125 percent of the charger output. Read the other way, a breaker supports a charger drawing 80 percent of its rating. That single rule explains why a 50 amp circuit gives you a 40 amp charger, and it is the most common thing people get wrong when shopping by amperage alone.
| Charger | Breaker | Power | Copper | Typical use |
|---|---|---|---|---|
| 12 A | 15 A | 2.9 kW | 14 AWG | A standard 120 volt household outlet. |
| 16 A | 20 A | 3.8 kW | 12 AWG | A dedicated 120 volt 20 amp circuit, or a 240 volt 6-20 outlet. |
| 24 A | 30 A | 5.8 kW | 10 AWG | The dryer-circuit case. Common with splitters on an existing 14-30. |
| 32 A | 40 A | 7.7 kW | 8 AWG | Plenty for a car with a 6.6 or 7.2 kW onboard charger. |
| 40 A | 50 A | 9.6 kW | 6 AWG | The most common home install. Fits a NEMA 14-50 outlet. |
| 48 A | 60 A | 11.5 kW | 6 AWG | Hardwired only. Saturates almost every onboard charger sold. |
| 64 A | 80 A | 15.4 kW | 4 AWG | Rare. Very few vehicles can use it. |
| 80 A | 100 A | 19.2 kW | 3 AWG | Essentially the F-150 Lightning case only. |
Every calculator on the site
- CALC-01 Charge Time Calculator Hours to full from battery size, charger output and starting state of charge. Read it
- CALC-02 Breaker Size Calculator The 125 percent continuous-load rule applied to any charger output. Read it
- CALC-03 Panel Load Calculator Whether your existing service has room for the circuit at all. Read it
- CALC-04 Wire Gauge Calculator Conductor size for the amperage, the run length and the insulation type. Read it
- CALC-05 Voltage Drop Calculator What a long run costs you in volts, and when to size up. Read it
- CALC-06 Installation Cost Calculator Parts plus labour for your run length, panel situation and finish. Read it
- CALC-07 Charging Cost Calculator Cost per charge from your utility rate and battery size. Read it
- CALC-08 Cost Per Mile Calculator Cents per mile at home, against pump prices and public chargers. Read it
- CALC-09 Payback Calculator How long the install takes to pay for itself versus public charging. Read it
- CALC-10 Time-of-Use Savings Calculator Annual savings from moving every charge to the off-peak window. Read it
- CALC-11 Solar Charging Calculator How much of a charge an array of a given size actually covers. Read it
What these calculators are and are not
They are planning aids. They exist so you can arrive at a conversation with an electrician knowing roughly what the answer should be, spot a quote that is out of line in either direction, and avoid buying hardware your car or your panel cannot use.
They are not electrical certification and they are not a code calculation. A web form cannot see your conductor temperature ratings, your panel bus rating, your ambient temperatures, the loads you forgot to mention, or the local amendments your jurisdiction has adopted. Any of those can move an answer by a wire size or an entire circuit.
The rule that governs everything on this site: a licensed electrician must size and install the circuit, a permit and an inspection are normally required, and nobody should attempt 240 volt wiring themselves. An EV charger is a continuous high-current load running for hours every night, and the failure mode for getting it wrong is heat inside a wall over hundreds of hours rather than an immediate obvious fault.
Where the calculators lead
Once the numbers are settled, the buildouts price three complete installs item by item, with every product linked and the totals stated including labour. The Level 2 charger roundup compares specific hardware at three budgets, and the reference charts hold the full tables the calculators draw on.
If you are still at the stage of working out what your car can accept, start with the battery capacity chart or find your model in the by vehicle section. The onboard charger limit is the single number that determines how much circuit is worth paying for.