How many EV chargers does a workplace need?

In short

Start with real employee demand, not total headcount. Estimate how much bookable charger time you already have, compare it with when employees actually need to charge and look for repeated requests that cannot be accommodated. Better scheduling can sometimes make existing chargers serve more drivers; persistent unmet demand after reasonable sharing is a stronger case for additional capacity.

Do not start with total employee headcount

A workplace with 500 employees does not automatically need more chargers than a workplace with 100 employees. The useful number is how many people are likely to depend on workplace charging at the same site and on the same days.

Before estimating charger requirements, ask employees about the factors that actually affect workplace charging demand.

Whether they already drive an EV or expect to do so soon
How many days they normally drive to the workplace
Their typical commuting distance
Whether their vehicle remains parked for most of the workday
Whether they can charge reliably at home
Whether they would actually use workplace charging
Which workplace sites they normally use

The result is a demand picture rather than a simple percentage of total employees.

Turn the workday into available charger-hours

A simple first calculation is the amount of bookable time available across the chargers.

Available charger-hours = number of bookable chargers × bookable hours per charger

For example, four chargers available for eight bookable hours provide 32 charger-hours of theoretical daily access.

If every charging turn lasted two hours, those 32 charger-hours could theoretically contain sixteen two-hour bookings. That is not a promise that sixteen drivers can always be served. Demand may overlap, chargers may be unavailable and individual charging needs vary. The calculation simply shows that charger count alone does not describe the amount of access that can be scheduled.

Peak overlap matters more than the daily total

A workplace can have enough charger-hours across the day and still have a capacity problem at a particular time.

If most employees want to charge immediately after arriving in the morning, the limiting factor is the number of simultaneous charging spaces during that period. The same number of charging requests may be easy to serve if drivers can use different parts of the day.

This is why capacity planning should look at both total requested charging time and when that time is requested.

Worked example: eight drivers and four chargers

Assume a workplace has four shared chargers available from 08:00 to 16:00. That gives 32 charger-hours of theoretical access.

On Monday, eight employees each request a two-hour charging turn. Their total requested time is 16 charger-hours — only half of the theoretical daily availability.

But six drivers request 09:00–11:00 and two request 11:00–13:00.

Between 09:00 and 11:00, four chargers can provide only eight charger-hours, while the six requests require twelve charger-hours. Two drivers therefore cannot be accommodated in that period.

If two of those drivers can shift to 11:00–13:00, the four chargers can serve all eight requests without adding hardware.

If six drivers repeatedly and genuinely require the same 09:00–11:00 period and cannot shift, the workplace has a real peak-capacity constraint even though much of the rest of the day remains free.

The example is deliberately simple, but it shows why a fixed “drivers per charger” ratio misses the scheduling problem.

Separate poor sharing from a real capacity shortage

Before adding another charger, check whether existing charging time is being lost through avoidable coordination problems.

Long reservations that use more time than drivers need
Unused bookings that are not cancelled
Vehicles occupying charging spaces beyond their allocated time
All drivers competing for the same morning period when some could charge later
Employees being unable to see when a charger will become available
No way to record charging requests that could not be fulfilled

Clear availability, defined charging turns and released cancellations can improve access without increasing the physical charger count. This is also why one workplace charger can sometimes serve more than one vehicle during a workday.

Look at unmet demand

High utilisation does not automatically mean that another charger is required. A charger can be busy because the existing capacity is being used effectively.

A stronger signal is repeated unmet demand: employees need charging time, the existing chargers and reasonable scheduling rules cannot accommodate it, and the same constraint continues across multiple days or periods.

Track when requests cannot be served, how much charging time was requested and whether alternative times were available. That makes it easier to distinguish a busy schedule from insufficient capacity.

When is another charger justified?

Additional charging capacity becomes easier to justify when several of these conditions occur together:

Charging requests repeatedly exceed available capacity during the same periods
Drivers cannot reasonably shift those requests to other available times
Existing chargers are already being shared with appropriate booking durations
Cancelled or returned charging time does not materially solve the shortage
The number of employees depending on workplace charging is increasing
Unmet charging demand persists rather than appearing only on isolated busy days

The scheduling question is only one part of an infrastructure decision. A qualified installer, electrician and, where relevant, the local utility must assess electrical supply, charger power, load management, installation cost and other technical requirements.

Workplace EV charger capacity checklist

How many employees currently need workplace charging?
How many additional employees are likely to need it in the near term?
On which days are those employees normally at the site?
Which charging periods do they actually request?
How many charger-hours are bookable each day?
How much of the demand overlaps at peak times?
Can drivers reasonably use different charging periods?
Are unused reservations released back into the schedule?
How often are valid charging requests left unserved?
Is unmet demand recurring or only occasional?
Have electrical and installation constraints been assessed separately by qualified specialists?

Where Charge Roster fits

Charge Roster helps workplaces understand the scheduling side of capacity. Employees reserve charging time against the chargers and availability configured for the site, while the workplace can see the shared schedule and where charging requests cannot be accommodated.

That information helps answer a practical question: can the existing chargers serve more drivers through better sharing, or is demand still being left unserved after the available time is organised effectively?

Charge Roster does not measure electrical capacity, charger power or energy delivered and does not control charging hardware. Those technical questions remain with the charging equipment, installer, electrician and utility.