A practical field guide · Free to use
EV Charging Session Cost Example
A unit rate alone may not describe the whole charging bill. This worked example keeps energy, connection, parking and idle charges separate so you can reproduce the total using the terms for your own charger.
Collect the applicable tariff
Record the operator, location, tariff source and the time you checked it. Where access depends on an account, membership or building arrangement, note which terms apply to you. A price from another location or an old screenshot is not enough to establish the cost of the session you are planning.
Identify the units before entering numbers. Energy may be priced per kWh, while parking and idle charges may use time. A connection charge can be a fixed amount. Keep each rate beside its trigger, any minimum or cap, and whether the displayed amount includes applicable taxes. If those terms are unclear, ask the operator.
Work through a fictional session
Suppose the charger bills twenty kWh at forty pence per kWh. The energy component is £8. Add a £1 connection fee and three hours of parking at £2 per hour: £6. If the session also incurs thirty idle minutes at ten pence per minute, that component is £3. The illustrative total is £18.
These are invented numbers, not current prices from an operator. The effective total divided by billed energy is ninety pence per kWh. That figure describes this whole example session, including non-energy charges. It should not be relabelled as the operator's advertised electricity rate or used as a prediction for a different session.
Check when each time charge starts and stops
Parking time, plugged-in time and idle time may have different definitions in the applicable terms. Record the start and end of each chargeable period. Do not assume a parking fee stops when charging stops, or that an idle fee applies throughout the whole connection. Avoid counting the same time fee twice.
If your available evidence does not establish the billable duration, record a scenario with its assumption. For example, compare leaving promptly with remaining connected for another half hour only when the tariff terms support that distinction. A hypothetical behaviour change is not a saving already achieved.
Compare only choices you can make
Residents using a building-selected provider may not be able to change operators. Start with practical decisions within your control, such as timing or moving the vehicle when allowed. Where no alternative is available, the worksheet can still explain a charge without pretending to create a cheaper option.
After the session, compare the estimate with the receipt using the billed energy and the actual fee lines. Record any discrepancy as a question for the provider. ChargeWindow performs arithmetic on entered terms; it does not verify every tariff, adjudicate disputes or guarantee savings. Keep the original tariff and receipt for your own checks.
| Energy | 20 kWh × £0.40 = £8.00 |
|---|---|
| Connection | £1.00 once |
| Parking | 3 hours × £2.00 = £6.00 |
| Idle | 30 minutes × £0.10 = £3.00 |
| Total / effective cost | £18.00 / 20 kWh = £0.90 per kWh |
Your blank worksheet
Download the text file and complete it in your own notes, or print this page. No account or purchase is required for this worksheet. Your completed notes are not submitted by this page.
- Operator / location / account tariff:
- Tariff source and checked date:
- Energy kWh × rate:
- Connection fee and trigger:
- Parking duration × rate:
- Idle duration × rate and trigger:
- Other stated fees / caps / tax basis:
- Estimated total:
- Actual receipt total and billed energy:
- Difference, explanation and available next action: