Project inputs
Use this planner to estimate charger quantity from parking demand, utilization, and policy coverage targets.
Example data table
Use these sample scenarios to sanity-check inputs before final design.
| Scenario | Parking | EV share | Need charge | Type | Ports/charger | Target utilization | Estimated chargers |
|---|---|---|---|---|---|---|---|
| Retail daytime | 180 | 20% | 30% | Level 2 (7.2 kW) | 2 | 40% | 6–10 |
| Office long dwell | 320 | 35% | 45% | Level 2 (11 kW) | 2 | 35% | 16–24 |
| Highway stop | 60 | 25% | 60% | DC Fast (150 kW) | 1 | 45% | 4–8 |
Formula used
ev_visits = vehicle_visits × (EV_share ÷ 100)
sessions_needed = ev_visits × (EVs_needing_charge ÷ 100)
sessions_per_charger = sessions_per_port × ports_per_charger
chargers_demand_adj = chargers_demand × (1 + redundancy% ÷ 100) × (1 + growth% ÷ 100)
chargers_final = ceil( max(chargers_demand_adj, chargers_coverage, minimum_chargers) )
How to use this calculator
- Enter total parking spaces and expected daily turnover.
- Set EV share and the percent of EVs that will plug in.
- Choose a charger type and review session duration defaults.
- Set operating hours and a realistic utilization limit.
- Add redundancy and growth allowances for resilience.
- Use coverage target to match policy or owner goals.
- Press Calculate to see chargers, ports, and connected load.
- Export CSV for schedules and download PDF for submittals.
Demand-driven sizing
Sizing begins with traffic and parking behavior. Multiply parking spaces by daily turnover to estimate vehicle visits. Apply the expected EV share, then the percentage that typically plugs in, to obtain charging sessions needed per day. This demand number is the foundation for stall layout, signage, and realistic queue control during busy periods.
Utilization and dwell time
Daily capacity is governed by operating hours, a utilization limit, and average session duration. Sessions per port equals available hours multiplied by utilization, divided by session hours. Multiply by ports per charger to estimate sessions per charger per day. Longer dwell reduces throughput, so office and residential sites usually need more ports than retail with short stays.
Coverage and compliance targets
Many construction programs also require minimum coverage, such as a target percent of parking served by charging ports. The calculator converts the coverage target into chargers by dividing by ports per unit. It then compares coverage sizing with demand sizing and enforces the larger value. Use the minimum chargers input to reflect codes, owner standards, and bid documents.
Resilience and growth allowances
Redundancy and growth provide practical headroom. Redundancy covers downtime, maintenance, blocked stalls, and seasonal peaks. Growth allowance anticipates adoption increases and changing tenant mixes. The calculator combines both as a multiplier on demand chargers, supporting phased construction and future expansions. This helps you size conduit banks, spare breakers, and distribution gear without overbuilding today.
Electrical planning outputs
After quantity, evaluate electrical implications. Connected load equals total ports times power per port, giving a worst‑case nameplate demand. The energy estimate uses an effective delivered power factor and session duration to approximate daily kWh. Use these outputs to coordinate service upgrades, transformer selection, meter arrangements, and load management strategies like scheduling or power sharing. For budgeting, pair the count with civil scope: trenching, bollards, pedestals, striping, and communication. Document assumptions, then validate with utility and equipment vendors before final IFC drawings and procurement to avoid change orders at commissioning later.
FAQs
1. How does the calculator estimate daily charging demand?
It converts parking capacity into visits using turnover, then applies EV share and the percent of EVs that plug in. The result is expected charging sessions per day for planning.
2. What utilization value should I use for design?
Use a conservative target to reduce queues. Many planners start around 30–50% depending on dwell time, enforcement, and reliability. Lower targets increase charger quantity but improve service.
3. Why does ports per charger matter?
Ports determine how many vehicles can charge concurrently. Dual‑port units often reduce equipment count, but they still add electrical load. Use the value that matches the selected product configuration.
4. What is the difference between demand sizing and coverage sizing?
Demand sizing is based on expected sessions and throughput. Coverage sizing is a policy ratio tied to parking count. The calculator installs the higher requirement to meet both performance and standards.
5. How are redundancy and growth applied?
They form a multiplier on demand-based chargers. Redundancy covers downtime and peaks, while growth accounts for future adoption. Adjust them to match phasing plans and client risk tolerance.
6. Does the connected load equal actual peak demand?
Connected load is the nameplate worst case if all ports run at full power. Actual demand may be lower with power sharing or load management. Confirm final service sizing with electrical engineering.