Battery range starts with usable watt-hours—not the sticker on the downtube. This guide shows how to calculate electric bike range from pack capacity, discharge efficiency, and the Wh/km your route actually demands.
Benefits
- Centers the battery: nameplate Wh × pack efficiency = energy available for the motor.
- Links battery size to km via assist, mass, and wind/terrain multipliers on Wh/km.
- Helps compare 400 Wh vs. 625 Wh packs on the same commute profile before you buy.
How it works
- Look up or estimate battery Wh (voltage × Ah, or manufacturer spec).
- Apply pack efficiency (88–95%) for BMS and drivetrain loss.
- Divide usable Wh by route Wh/km—adjusted for assist level and conditions—to get battery-backed range.
FAQ
How do I calculate electric bike range from battery Wh?
Usable Wh = pack Wh × efficiency. Range ≈ usable Wh ÷ Wh/km. A 625 Wh pack at 90% efficiency with 11 Wh/km consumption → about 51 km. Swap pack size in the calculator to see km gained from a larger battery.
How many Wh do I need for a 30 km commute?
Multiply target km by expected Wh/km, then divide by pack efficiency. At 12 Wh/km and 92% efficiency: 30 × 12 ÷ 0.92 ≈ 391 Wh minimum—add 15–25% margin for headwinds, cold, or aging cells.
Is voltage or Ah more important for range?
Range depends on total Wh (V × Ah), not voltage alone. A 48 V 13 Ah and 36 V 17 Ah pack are both about 624 Wh—similar range if efficiency and consumption match. Voltage affects sag and motor behavior, not nameplate energy.
Technical specifications
- Battery Wh: from label (V × Ah) or OEM spec sheet.
- Usable Wh = Wh × pack_efficiency_fraction.
- Range_km = usable_Wh ÷ effective_Wh/km.
- Related: ebike-battery-cycle-life, ebike-voltage-sag, ebike-charge-time.