E-bike range estimator

Share a scenario

A shared link includes the numeric assumptions above, including combined rider/cargo weight. Anyone with the link can read them. Values are calculated locally; these inputs are not saved by the calculator.

The math, openly

Energy above reserve = label Wh × usable-capacity fraction × (starting-charge fraction − reserve fraction). Measured range = available Wh ÷ entered Wh/km. Scenario range uses rolling demand, air drag and climbing energy, subtracts the assumed rider contribution, then allows for battery-to-wheel efficiency and auxiliary power.

Rolling force is modeled as mass × 9.80665 × the coefficient you enter. Air drag uses ½ × air density × CdA × relative air speed squared. Climbing uses mass × 9.80665 × ascent; 3,600 joules equal one watt-hour. Assumed sea-level air density is 0.0765 lb/ft³ (1.225 kg/m³) at 59°F (15°C), scaled inversely with absolute temperature at constant pressure. Altitude, humidity and crosswinds are omitted.

This steady-speed calculation omits repeated acceleration, stop/start duty cycles, motor torque/power limits, traction, component temperature limits, battery voltage sag, battery-management cutoffs and changing gradients. Tailwinds are allowed to reduce drag to zero, but never supply modeled propulsive energy. High pedal contribution can reduce motor demand to zero; that produces no finite battery-range estimate if auxiliaries are also zero.

Use measured consumption on comparable rides when available, plan a reserve and revise assumptions as conditions change.

Source scope

Physics references checked October 11, 2026: NASA: drag equation, NASA: ideal-gas air density, and OpenStax: work and power. They support the equations, not the illustrative coefficients, default range or bike-specific accuracy. No external range-assistant output was copied; Bosch’s support page was unavailable during this check.

How far does the same battery go at different consumption?

These are illustrative arithmetic examples with 100% assumed usable capacity, a full starting charge and a 20% reserve. They are not averages for road, cargo or mountain bikes. The denominator matters as much as the battery label.

How should I use assistance and tyre presets?

Start by choosing a scenario, then edit its numeric assumptions. Assistance changes our assumed rider contribution, not a manufacturer's motor setting. The rider-power input is mechanical power at the wheel for this simplified calculation; it is not a fitness measurement or a prescribed effort. Tyre presets change an illustrative rolling-resistance coefficient; they cannot identify your tyre's actual rolling loss.

If you change one assumption, keep the others fixed to see its isolated effect. Then combine changes you expect on your actual ride. A headwind, climbing and heavy load can occur together. Their real effects vary along a route, while this model uses steady speed and route-average climbing. It cannot check sustained torque, traction or a steep section's motor limits.