How the session price is built
- Energy = kWh added × the per-kWh price in the app. Networks meter at the charger, so this does not add home charging losses.
- Session fee = a flat charge some networks add on top of energy. Use 0 if yours does not.
- Idle fee = minutes the car stays plugged in after charging × the per-minute rate. Unplugging when it finishes makes this zero.
- Home comparison = the same battery kWh ÷ 0.90 × your residential rate. The 90% is the Level 2 wall-to-battery figure used in our charging cost calculator.
How the membership check works
Monthly savings = kilowatt-hours you will fast charge × (standard price − member price) − the monthly fee. Break-even is the fee divided by that per-kWh gap. If the member price is not actually lower, the tool says the membership does not pay.
The default gap is Tesla’s October 2026 Supercharger index, not the national $0.55 average. Other networks use different plans. Replace both prices with the two rates your app shows. The worked example is in the commute charging guide.