Regenerative Braking Energy Calculator

About this calculator

Regenerative braking recovers a fraction of a vehicle's kinetic energy (KE = ½mv²) by running the electric motor as a generator during deceleration, converting motion back into stored battery charge instead of dissipating it entirely as brake-pad heat. The energy actually reclaimed depends on the drop in speed — from v₁ down to v₂ — and a recovery efficiency factor that accounts for losses in the motor, inverter and battery charging path, typically 60-70% in real-world EVs and hybrids rather than the full theoretical kinetic energy difference.

This calculator takes a vehicle's mass, its speed before and after braking, and a recovery efficiency percentage, then estimates the energy actually reclaimed in kilojoules or watt-hours. Automotive and EV powertrain engineers modeling energy budgets, hybrid/EV owners curious how much range city braking recovers, and students studying regenerative systems use it to quantify how braking pattern and vehicle mass translate into real energy savings rather than relying on a manufacturer's headline efficiency number.