EV Charging Time Calculator
Estimate how long your electric car will take to charge — including the real-world slowdown above 80% on rapid chargers.
How does the EV charging time calculator work?
At its simplest, charging time is energy needed (kWh) divided by charging power (kW). But two real-world factors change this significantly: charging isn't 100% efficient (some energy is lost as heat), and DC rapid charging slows down considerably once the battery passes around 80% — a home AC charger doesn't have this same taper. This calculator accounts for both, rather than giving you an oversimplified flat-rate answer.
3 worked examples
Example 1 — Overnight home charging
A 60kWh battery, 20% to 80% charge, on a 7kW home charger (car's max AC rate is higher, so the charger is the limiting factor).
60kWh × (80% − 20%) = 36kWh, ÷ 88% AC efficiency = ~40.9kWh drawn from the wall
Charging time:40.9kWh ÷ 7kW = ~5 hours 51 minutes — comfortably an overnight charge
Example 2 — Public rapid charging, staying under 80%
Same 60kWh battery, 20% to 80%, on a 50kW rapid charger (car's max DC rate is 100kW, so the charger caps the speed at 50kW).
36kWh needed, ÷ 93% DC efficiency = ~38.7kWh, ÷ 50kW = ~46 minutes
Example 3 — Rapid charging past 80%
Same car and charger, but charging from 20% all the way to 100% instead of stopping at 80%.
~46 minutes, as in Example 2
Phase 2 (80%→100%, tapered):20% of the battery (12kWh) charged at roughly 45% of peak power due to the taper — this phase alone takes ~34 minutes
Total:~1 hour 21 minutes — the last 20% takes almost as long as the first 60%
Example 3 is the single most important thing to understand about rapid charging: going from 20% to 80% takes 46 minutes, but continuing on to 100% adds another 32 minutes for just 20 more percentage points. This is exactly why most experienced EV drivers stop rapid charging at 80% on a road trip.
Why rapid charging slows down above 80%
Lithium-ion batteries can safely accept a very high charge rate when they're relatively empty, but as they fill up, the battery management system deliberately reduces the charging rate to protect the battery's long-term health and safety. This isn't a limitation of the charger — it's the car's battery management system intentionally slowing things down.
This tapering is specific to DC rapid and ultra-rapid charging. Home and workplace AC charging is already slow enough that the taper effect is barely noticeable — the charger itself, not the battery's willingness to accept charge, is almost always the limiting factor at those lower power levels.
Charging speeds by type
| Charging type | Typical power | Roughly adds per hour |
|---|---|---|
| Slow (3-pin domestic socket) | 2.3kW | ~10 miles |
| Home/workplace AC (single-phase) | 7kW | ~30 miles |
| Home/workplace AC (three-phase) | 22kW | ~90 miles |
| Public rapid DC | 50kW | ~200 miles |
| Public ultra-rapid DC | 100–350kW | ~400+ miles (subject to taper and car's max rate) |
"Miles per hour" figures are rough averages assuming typical efficiency — your actual figure depends on your specific car's real-world efficiency, covered in more detail in our EV running costs guide.
Charging losses explained
Not all the energy drawn from the charger ends up in the battery — some is lost as heat during conversion. AC charging (home and workplace) is generally slightly less efficient than DC rapid charging, because AC power has to be converted to DC by the car's onboard charger, while DC chargers bypass this step by feeding DC power directly to the battery. This calculator assumes roughly 88% efficiency for AC and 93% for DC as typical, general estimates.
What this calculator can't tell you
Your car's exact charging curve
Every EV model has its own specific charging curve, and some taper earlier or more aggressively than others. This calculator uses a general approximation, not your specific vehicle's actual published curve.
Temperature effects
Cold weather significantly slows charging, sometimes dramatically, because the battery management system limits charge rate to protect a cold battery. A charging session estimated at 46 minutes in mild weather could take considerably longer on a cold winter day, especially if the battery hasn't been pre-conditioned.
Battery degradation
An older battery with reduced capacity will have a different effective kWh figure than when the car was new, which this calculator doesn't automatically account for — enter your battery's current usable capacity if you know it's degraded from new.
Charger availability and queuing
This is purely a charging-speed calculation — it doesn't account for time spent waiting for an available charger, which can be the larger real-world time cost on busy public networks.
Common mistakes
Assuming a flat charging rate for the whole session
The single most common error — treating "50kW charger" as meaning the whole session happens at 50kW, when the taper above 80% means the real average is significantly lower for a full charge.
Ignoring the car's own maximum charging rate
Plugging into a 150kW ultra-rapid charger doesn't help if your car's maximum DC charging rate is only 50kW — the lower of the two figures always determines your actual speed.
Not accounting for charging losses
The energy your electricity meter (or the public charger's billing) shows isn't all reaching the battery — a portion is lost as heat, particularly on AC charging.
Planning a road trip to 100% every stop
As Example 3 shows, charging past 80% on a rapid charger takes disproportionately long. Most efficient road-trip charging strategies involve multiple shorter stops to 70–80%, rather than fewer stops all the way to 100%.
Tips for faster, cheaper charging
- Charge to 80% on rapid chargers during a road trip, not 100% — it's faster overall across multiple stops than fewer full charges
- Charge to 100% overnight at home when you have the time — the taper matters far less when you're not waiting around for it
- Pre-condition the battery before a rapid charging stop if your car supports it (often via the navigation system routing to a charger) — this can significantly improve charging speed in cold weather
- Check your car's actual maximum DC charging rate before assuming a higher-power charger will help — many EVs cap well below 150kW+
- Use off-peak home electricity tariffs for overnight charging to reduce cost — see our EV running costs guide for typical tariff comparisons
⚡ See the full running cost picture
Charging time is one piece — see how EV running costs compare to petrol, including charging cost per mile.
Use the EV vs Petrol Calculator →How we calculate
Energy needed (kWh) = Battery capacity × (Target % − Current %) ÷ 100, then divided by an efficiency factor (88% AC, 93% DC) to estimate energy drawn from the source.
Peak charging power = the lower of charger power and your car's maximum charging rate.
AC charging: Time = Energy needed ÷ peak power, with no taper applied.
DC charging: If the charge session stays entirely at or below 80%, the same flat calculation applies. If it crosses or starts above 80%, the calculation splits into two phases — a full-speed phase up to 80%, and a tapered phase (modelled at roughly 45% of peak power) from 80% to the target.
Frequently asked questions
Why does EV charging slow down above 80%?
The battery management system deliberately reduces the charge rate above roughly 80% to protect the battery's long-term health, particularly on DC rapid charging. This is a safety and longevity feature, not a charger limitation.
How long does it take to charge an EV from empty to full at home?
For a typical 60kWh battery on a 7kW home charger, expect roughly 8–9 hours from near-empty to full, accounting for typical AC charging losses. A 22kW three-phase charger would reduce this to roughly 3 hours.
Does a more powerful public charger always charge faster?
Only up to your car's own maximum charging rate. Plugging a car with a 50kW maximum DC rate into a 150kW ultra-rapid charger won't charge any faster than plugging into a 50kW charger — the lower of the two figures always applies.
Why do EV drivers often stop charging at 80% on road trips?
Because the last 20% typically takes almost as long as the first 60–80% on a rapid charger, due to the taper. For multi-stop road trips, several shorter stops to around 80% are usually faster overall than fewer stops charging all the way to 100%.
Does cold weather affect EV charging speed?
Yes, significantly. The battery management system limits charge rate to protect a cold battery, which can meaningfully slow down a charging session, especially on rapid chargers, unless the battery has been pre-conditioned beforehand.
References & data sources
- Zap-Map. UK public charging network data and typical charging speed benchmarks by connector and charger type.
- Manufacturer specification sheets. Vehicle-specific maximum AC and DC charging rates, used as the basis for the "car's max charging rate" input.
Unlike our tax and legal calculators, EV charging speed isn't set by a single official body — it depends on your specific vehicle's battery management system, the charger hardware, and conditions on the day. This calculator gives a realistic estimate based on typical published behaviour, not a guarantee for your exact car and charger combination.