There is no standard ratio — the right number comes from three figures you can gather in a week: how many EVs park at your site daily, how long each one stays, and how much energy each needs. Dwell time does the heavy lifting. Cars parked for a full shift can share: one Level 2 port can serve two cars a day with a midday swap, so a car park full of EVs rarely needs a charger per car.
Key Takeaways
- No standard ratio exists: count EVs, dwell time and daily energy need, then do the arithmetic.
- Long dwell time means sharing — one Level 2 port can serve two cars a day with a midday swap.
- Swapping behaviour halves the port count of an otherwise identical site.
- Build electrical capacity for growth, install ports for near-term demand, and measure before expanding.
The Three Inputs
- EVs on a typical day. Count them, including pool and fleet vehicles — and ask around: staff often plan to buy an EV once charging exists.
- Dwell time. An office car parked all day is a different problem from a depot van parked for two hours. Long dwell means low power and sharing; short dwell means more ports or faster ones.
- Energy per car per day. Most workplace charging is a top-up, not a fill. As an illustration, a car needing about 10 kWh for its commute takes roughly an hour and a half on a 7 kW port — well inside a working day, with time to spare for a second car.
Our workplace EV charging program guide covers the wider programme — policy, payment and rollout; this article is only the arithmetic.
A Worked Example (Illustration, Not a Standard)
| Site pattern | EVs per day | Ports the method gives | Why |
|---|---|---|---|
| Office, all-day parking, midday swaps accepted | 10 | About 5 | Each port serves a morning and an afternoon car |
| Office, no swapping culture | 10 | About 10 | Each car keeps its port all day, however little it draws |
| Mixed site with short-stay visitors | 10 staff + visitors | Staff ports plus 1–2 extra | Short dwell cannot share; visitors need their own capacity |
| Shift site, cars parked 3–4 hours | 12 | About 6–8 | Ports turn over once, but sessions run closer to the dwell limit |
Read the table as a method, not a norm: behaviour moves the answer as much as hardware does — a site that swaps at lunch needs half the ports of one that does not.
Why Level 2 Fits Workplace Dwell Time
U.S. DOT figures put Level 2 charging at 7–19 kW, adding roughly 10–20 miles of range per hour — more than a parked-all-day car needs, which is why sharing works. DC fast charging, at 50–350 kW, solves a problem workplaces mostly do not have. Budgeting agrees: DOE-cited figures put a public Level 2 connector at about $3,500 for equipment plus $2,500 for installation, against $38,000–$90,000 plus $20,000–$60,000 for DC fast charging. Our breakdown of what commercial EV chargers cost and the commercial installation cost guide show where those figures go.
Start Smaller, Wire for More
- Install for today’s count, build capacity for tomorrow’s. Conduit, panel capacity and bay layout are cheap during the first installation and expensive to retrofit.
- Use load management instead of new supply. Shared circuits let more ports run on the electrical capacity you already have.
- Measure before expanding. A term of session data — how full the ports are, hour by hour — replaces guessing about when to expand.
- Count connectors, not just units. Dual-connector stations serve two bays; a “four-charger” plan may mean four units or four ports, and the difference is the whole budget.
Hardware That Matches the Method
Dual-connector AC hardware fits the sharing model: the EVDANCE EV-AC03201T dual-connector AC station provides two Type 2 connectors sharing up to 43 kW (22 kW per connector), with OCPP 1.6J and RFID so each session is attributed to a driver — the records that tell you when to expand. EVDANCE’s commercial EV charging solutions scale the same approach to larger sites.
Frequently Asked Questions
Is there an official chargers-per-employee ratio?
No standard or regulator publishes one: the right count depends on dwell time and daily energy need, which differ by site. A fixed ratio quoted without those inputs is a sales rule of thumb, not a requirement.
Should we size for the EVs staff will own in five years?
Size the electrical infrastructure for growth, but install ports for the next year or two of demand. Ports are quick to add once capacity and bays exist; idle ports bought early are capital sitting in a car park.
Do fleet and pool vehicles change the count?
Yes — count them separately. Vehicles that must leave fully charged on schedule share less flexibly than staff cars; a few guaranteed ports for them usually beats folding them into the general pool.
Related Reading
- How to Plan a Workplace EV Charging Program
- How Much Do Commercial EV Chargers Cost?
- How Much Does It Cost to Install a Commercial EV Charging Station?
- How Do Commercial EV Charging Stations Work?
