EV Charging Calculator
Calculate how long it takes to charge your electric vehicle and estimate the cost based on your electricity rate.
Battery Size
Charge Levels
Charger Power
Electricity Price
Charging Estimate
Assumptions: Charging time assumes constant power delivery. Real-world times vary based on battery temperature, state of charge, and vehicle charging limits. DC fast charging above 80% SOC is significantly slower due to battery protection.
Calculate how long it takes to charge your electric vehicle and what it costs. Works for all EVs, charger types, and electricity rates.
This free EV charging calculator from Invoice Mama helps you plan charging sessions with confidence. Whether you're charging at home overnight or stopping at a DC fast charger on a road trip, knowing the time and cost upfront makes a real difference. Enter your battery size, current charge level, and charger power to get instant estimates.
Our calculator accounts for real-world factors like charging efficiency and helps you compare peak vs off-peak electricity rates. It's a handy tool for EV owners, fleet managers, and anyone thinking about making the switch to electric.
How This EV Charging Calculator Works
The simple math behind your charging estimates
Our calculator uses straightforward formulas to estimate charging time and cost. Here's what happens when you enter your details:
- 1
Calculate Energy Needed
Energy (kWh) = Battery Size × (Target % - Current %) ÷ 100. For example, a 75kWh battery going from 20% to 80% needs 45kWh of energy.
- 2
Account for Efficiency
Not all energy from the grid reaches the battery. We factor in 85-92% efficiency to show actual grid consumption and energy losses.
- 3
Calculate Charging Time
Time (hours) = Energy Needed ÷ Charger Power. A 45kWh charge at 7kW takes about 6.4 hours (slightly more accounting for efficiency).
- 4
Calculate Cost
Cost = Energy from Grid × Electricity Price. We can also compare peak vs off-peak rates to show potential savings.
Note: Real-world charging isn't perfectly linear. DC fast charging tapers above 80% state of charge, and various factors like battery temperature affect speeds. Our estimates are based on ideal conditions and should be used as a guide.
Charging Speed Explained: kW vs kWh
Understanding the difference between power and energy
Confused about kW and kWh? You're not alone. Here's the simple explanation:
- kW (Kilowatts) = PowerThis is the rate of energy transfer - how fast you're charging. Think of it like water flow rate. A 7kW charger delivers 7 kilowatts of power continuously.
- kWh (Kilowatt-hours) = EnergyThis is the total amount of energy stored or transferred. Think of it like the volume of water in a tank. A 75kWh battery holds 75 kilowatt-hours of energy.
- The RelationshipTime = Energy ÷ Power. Charging 45kWh at 7kW takes 45÷7 = 6.4 hours. Higher kW means faster charging, larger kWh means more storage.
Charger Type | Power (kW) | Time to Add 50kWh | Best For |
|---|---|---|---|
| Level 1 (Outlet) | 1.8-2.4 kW | 21-28 hours | Emergency, PHEVs |
| Level 2 (Home) | 7-22 kW | 2.3-7 hours | Daily home charging |
| DC Fast | 50-150 kW | 20-60 minutes | Road trips |
| Ultra-Fast DC | 250-350 kW | 9-12 minutes | Quick top-ups |
What Affects EV Charging Cost?
Understanding your electricity bill and charging expenses
- Electricity RatesHome rates vary from $0.10-$0.40 per kWh depending on location and provider. Time-of-use plans offer cheaper off-peak rates (often 50% less) for overnight charging.
- Charging EfficiencyYou pay for more energy than goes into the battery. Typical losses of 8-15% mean a 50kWh charge actually draws 55-58kWh from the grid.
- Charger TypePublic DC fast chargers cost $0.40-$0.70 per kWh - often 2-3x home rates. Some charge by time or session, adding costs for slower-charging vehicles.
- Network FeesCharging networks may add session fees, idle fees (for staying plugged in after charging), or membership costs. Free destination chargers exist at shops and hotels.
- Vehicle EfficiencyMore efficient EVs (lower kWh per 100km) cost less per kilometer driven. Efficiency ranges from 13kWh/100km (small EVs) to 25kWh/100km (large SUVs).
- Climate ControlPreconditioning the cabin while plugged in uses grid power instead of battery. Heating in winter and AC in summer can add 10-20% to charging costs.
Tips to Charge Cheaper and Faster
Practical advice from real EV owners
Save Money on Charging
- Switch to a time-of-use electricity plan and charge overnight during off-peak hours
- Install solar panels and charge during the day when generating excess power
- Use free destination chargers at shopping centres, hotels, and workplaces
- Charge to 80% on road trips - the last 20% takes disproportionately longer on DC fast chargers
- Look for charging network apps that aggregate the cheapest nearby options
- Some networks offer memberships with discounted per-kWh rates
Charge Faster
- Precondition your battery before arriving at a fast charger (many EVs do this automatically when navigating to one)
- Charge when the battery is warm from driving, not cold from sitting overnight
- Stop charging at 80% - the final 20% is much slower due to battery protection
- Check your car's maximum charging rate and choose chargers that match it
- Avoid charging multiple vehicles on the same charger cabinet (power may be shared)
- Keep your battery between 20-80% for the fastest charging curve
Pro Tip: If you run an EV charging business or offer mobile charging services, Invoice Mama makes it easy to create professional invoices for your customers. Track charging sessions, bill accurately, and get paid faster with our AI-powered invoicing tools.
Understanding Charging Efficiency
Where does the energy go?
When you charge an EV, not all electricity from the grid ends up in the battery. Energy is lost to heat in several places along the way. Understanding these losses helps you estimate costs more accurately.
Source of Loss | Typical Loss | Notes |
|---|---|---|
| Charger (EVSE) | 2-5% | Higher quality chargers are more efficient |
| Onboard Charger (AC) | 3-8% | Converts AC to DC for the battery |
| Battery Heating/Cooling | 2-5% | Thermal management during charging |
| Cable Resistance | 1-2% | Longer/thinner cables lose more |
| DC Fast Charging | 5-10% | High power = higher losses |
Total efficiency typically ranges from 85-92% for home AC charging and 80-90% for DC fast charging. Cold weather can drop efficiency to 75-80% as energy is used to heat the battery to safe charging temperatures. Our calculator defaults to 90% but lets you adjust based on your conditions.
Setting Up Home Charging
Your guide to charging at home
- 1
Assess Your Electrical Capacity
Check your switchboard for spare circuits. A 7kW charger needs a dedicated 32A circuit. Older homes may need a switchboard upgrade.
- 2
Choose the Right Charger
Most EV owners do well with a 7kW single-phase charger. If you have three-phase power and a compatible car, consider 11kW or 22kW for faster charging.
- 3
Get Professional Installation
Always use a licensed electrician. They'll ensure proper earthing, circuit protection, and compliance with local regulations. Expect $500-$1500 for installation.
- 4
Consider Smart Features
Smart chargers let you schedule charging for off-peak rates, monitor energy usage, and integrate with solar systems. Worth the extra investment.
Once your charger is installed, charging becomes as easy as plugging in when you get home. Most EV owners never visit a petrol station again - they wake up to a full battery every morning.
DC Fast Charging: What You Need to Know
Making the most of rapid charging on road trips
DC fast chargers bypass your car's onboard charger to deliver power directly to the battery at high speeds. Here's what affects your fast charging experience:
- Charging CurveFast charging isn't constant. Your car might accept 150kW at 20% battery but only 50kW at 70%. This is why charging 20-80% is much faster than 0-100%.
- Battery TemperatureCold batteries charge slowly. Many EVs precondition the battery when you navigate to a fast charger, warming it to optimal temperature before you arrive.
- State of ChargeThe emptier your battery, the faster it can accept charge. Arriving at 10-20% SOC maximizes charging speed. Above 80%, charging slows dramatically.
- Charger Power SharingSome charging stations share power between stalls. If another car is charging next to you, both may get reduced power.
For road trips, plan to charge to 60-80% at each stop. This maximizes speed and minimizes waiting. Use apps like PlugShare or A Better Route Planner to find chargers along your route.
Planning Your EV Charging
Quick answers to common questions
Most new EV owners worry about charging more than they need to. Here's the reality: if you can charge at home, you'll rarely think about it. Plug in when you arrive, unplug when you leave. Your car is always ready.
For those without home charging, workplace charging and destination chargers at shopping centres make EV ownership practical. Public fast chargers fill the gaps for longer trips.
Use this calculator to plan charging sessions, compare costs, and understand how different chargers affect your routine. The more you understand, the more confidently you can make the switch to electric.
Running an EV Charging Business?
Simplify your billing with Invoice Mama
If you install EV chargers, operate a charging network, or offer mobile charging services, you know billing can get complicated. Different rates, session fees, energy costs - it adds up to a lot of admin work.
Invoice Mama helps service businesses create professional invoices in seconds. Our AI-powered tools handle the heavy lifting - just describe the job and we generate a polished invoice ready to send. Track payments, manage customers, and spend less time on paperwork.
- Create invoices in 10 seconds with AI assistance
- Professional templates that make your business look great
- Track when clients view and pay invoices
- Free plan available - no credit card required
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Ready to Calculate?
Use our free EV charging calculator above
Whether you're planning a road trip, comparing home charger options, or just curious about charging costs, our calculator gives you the answers you need. Enter your battery details, select your charger type, and get instant estimates for time and cost. It's free, fast, and works for any electric vehicle.
If you run an EV charging business, install chargers, or offer mobile charging services, Invoice Mama helps you create professional invoices in seconds. Bill your customers accurately and get paid on time.