EV Charging Time Calculator
Estimate how long your electric car could take to charge, including the slowdown near the top on rapid chargers.
How does the EV charging time calculator work?
At its simplest, charging time is the energy needed (kWh) divided by the charging power (kW). Two real-world effects change that. Some energy is lost as heat, so you draw more from the charger than reaches the battery. And on DC rapid charging, a car slows the rate it accepts as the battery fills, particularly above about 80%.
This calculator allows for both with simple assumptions, rather than giving a flat-rate answer.
3 worked examples
Example 1 — Overnight home charging
A 60 kWh battery, 20% to 80%, on a 7 kW home charger. The car accepts at least 7 kW, so the charger is the limit.
60 kWh × (80% − 20%) = 36 kWh in the battery, ÷ 0.88 AC efficiency = about 40.9 kWh drawn from the wall
Charging time:40.9 kWh ÷ 7 kW = about 5 hours 51 minutes, comfortably an overnight charge
Example 2 — Public rapid charging, stopping at 80%
The same battery, 20% to 80%, on a 50 kW rapid charger, in a car that can accept up to 100 kW.
36 kWh ÷ 0.93 DC efficiency = 38.7 kWh, ÷ 50 kW = about 46 minutes
Example 3 — Rapid charging past 80%
The same battery and 50 kW charger, but the car can accept at most 50 kW, and you charge from 20% to 100%.
about 46 minutes, as in Example 2
Phase 2 (80% to 100%, slowed):12 kWh ÷ 0.93 = 12.9 kWh, at an assumed 45% of the car's 50 kW maximum (22.5 kW) = about 34 minutes
Total:about 1 hour 21 minutes. The last 20 percentage points take almost as long as the first 60.
Example 3 shows why many drivers stop rapid charging at around 80% on a journey. How much time you save depends on your car's own curve, so treat the 34 minutes as an illustration, not a prediction.
Why rapid charging slows down above 80%
One UK dealer guide says charging speed "will tail off significantly once a battery reaches 80% charge" and that the rate then tapers to protect the battery from overheating and damage. The slowdown is the car's battery management deliberately limiting what it accepts, not a fault in the charger.
On slower AC charging the car rarely needs to limit the rate, so this calculator applies no slowdown to AC sessions. Some rapid chargers also stop automatically at around 80%, according to another UK guide.
Charging speeds by type
| Charger type | Typical power | Energy delivered per hour (before losses) |
|---|---|---|
| Three-pin domestic socket | Up to about 3 kW | Up to about 3 kWh |
| Slow charge point | 3.6 kW | 3.6 kWh |
| Home or workplace fast (AC) | 7 kW | 7 kWh |
| Fast (three-phase AC) | 22 kW | 22 kWh, if your car can accept it |
| Rapid | 43–50 kW | 43–50 kWh |
| Ultra-rapid (DC) | 100–350 kW | Limited by the car's own maximum |
To turn kWh into miles, multiply by your car's miles per kWh, which varies with the car, speed and weather. For example, at 3 miles per kWh (an assumption), 7 kWh adds about 21 miles. Our EV running costs guide covers efficiency in more detail. Many cars can't accept 22 kW AC, so check your car's AC limit.
Charging losses explained
Not all the energy drawn from the charger reaches the battery. E.ON Next says roughly 10–25% of energy is lost to heat, cable resistance and conversion, with the best case on a warm day with a good wallbox and the worst case on a cold night using a three-pin plug. Losses occur in the car's onboard charger (which converts AC to DC), in battery heating or cooling, and in the cable.
The calculator assumes 88% efficiency for AC (a 12% loss) and 93% for DC. Both are simple assumptions inside, or close to, that range and are not measured figures for your car. Cold weather can push real losses higher.
What this calculator can't tell you
Your car's exact charging curve
Every model has its own curve. This calculator assumes a single slowdown above 80% (45% of the car's maximum), which is a simplification.
Temperature effects
E.ON Next notes that a cold battery has higher internal resistance and the car spends energy warming it. Expect longer sessions and larger losses in winter, particularly if the battery hasn't warmed up.
Battery ageing
An older battery may have less usable capacity. Enter the usable capacity you actually have if you know it.
Queues and availability
The calculator covers charging speed only, not time spent waiting for a free charger.
Common mistakes
Assuming a flat rate for the whole session
A "50 kW charger" doesn't mean 50 kW all the way to full. The slowdown near the top means the average rate is lower on a long session.
Ignoring the car's own maximum rate
A 150 kW charger doesn't help a car that can only accept 50 kW. The lower of the two figures sets your speed.
Forgetting charging losses
The energy shown on your meter or bill is more than reaches the battery.
Mixing up AC and DC limits
For home charging, use your car's maximum AC rate, which is usually much lower than its DC rate.
Tips for faster, cheaper charging
- On a journey, consider stopping rapid charging around 80% and compare the time saved against an extra stop
- Charge to your needed level overnight at home, where the speed of the last few percent matters less
- Pre-condition the battery before a rapid stop if your car supports it, because a warm battery charges more efficiently
- Check your car's maximum DC and AC rates before paying for a higher-power charger
- Check your tariff. Some suppliers offer cheaper overnight rates for EV charging, and our EV running costs guide has more
⚡ See the full running cost picture
Charging time is one piece. See how EV running costs compare with petrol, including the cost per mile of charging.
Use the EV vs Petrol Calculator →How we calculate
Energy drawn = battery capacity × (target % − current %) ÷ 100 ÷ efficiency. Efficiency is 0.88 for AC and 0.93 for DC (assumptions).
Peak power = the lower of the charger power and your car's maximum rate.
AC: time = energy drawn ÷ peak power, with no slowdown.
DC: up to 80% the charge runs at peak power. Above 80% the power is the lower of peak power and 45% of your car's maximum rate (an assumption). A session that crosses 80% is split into two phases, and one that starts above 80% runs entirely at the slowed rate.
Frequently asked questions
Why does EV charging slow down above 80%?
The car's battery management system reduces the rate it accepts as the battery fills, to protect the battery from overheating and damage. It is mainly noticeable on DC rapid charging.
How long does it take to charge an EV from empty to full at home?
With this calculator's assumptions, a 60 kWh battery on a 7 kW home charger takes about 9 hours 44 minutes from 0% to 100%. A 22 kW supply would take about 3 hours, but only if your car can accept 22 kW AC.
Does a more powerful public charger always charge faster?
Only up to your car's own maximum charging rate. The lower of the two figures sets your speed.
Why do EV drivers often stop charging at 80% on journeys?
Because the rate falls near the top on rapid chargers, the last part of the charge takes longer per percentage point than the rest. Whether an extra stop is quicker overall depends on your car and route.
Does cold weather affect EV charging speed?
Yes. A cold battery has higher internal resistance, and the car uses energy warming it, so sessions are typically slower and less efficient in winter. Charging soon after driving, when the battery is warm, helps.
References & data sources
- E.ON Next — Understanding where EV charging losses occur. The 10–25% loss range, where losses occur, and the effect of cold weather.
- Dick Lovett — Fast and rapid EV charging in the UK. Charger categories and the slowdown near 80%.
- Motoring Electric — Slow, fast and rapid charging explained. Typical charger power by type.
These are commercial and trade guides, not official sources. Charging speed isn't set by a regulator, and the calculator's loss and slowdown figures are simple assumptions. Check your car's handbook or manufacturer for its real charging curve.
Prakash
Prakash is the founder and editor of UK Driving Tools. He maintains the site's calculators and guides and checks the rates and rules they use against official UK sources, such as GOV.UK, the DVLA, HMRC and Transport for London, before publishing.
Pages are drafted with the help of AI tools and then checked by the editor. He isn't a lawyer, accountant or UK-qualified adviser, so every page lists its sources and states what its calculator can't tell you. Nothing on this site is legal or financial advice.
Pages on UK Driving Tools are drafted with the help of AI tools. Before publishing, the figures and rules on each page are checked against the official source named on the page, and calculator examples are tested against the working formula. Pages are updated when rates or rules change. Our Editorial Policy explains the full process, including how to report a mistake.
Spotted a mistake or an out-of-date rate? Let us know and we'll check it against the official source.