E-Bike Range Calculator
Plan a ride with conservative range bounds instead of one precise promise. Enter the battery, total load, assist behavior, route, and weather you expect.
Loading calculator…
How the estimate works
The calculator first reduces nameplate battery capacity by your estimated battery health and planned reserve. It then divides that usable energy by modeled watt-hours per kilometre. The calculation stays in metric units internally, even when you enter or view imperial values.
The model is versioned as BikeSize research seed v1. Bosch, Trek, Specialized, Shimano, and Grin support the choice and direction of the factors below. They do not supply or endorse BikeSize's coefficients.
| Model step | BikeSize assumption |
|---|---|
| Usable battery | Capacity × health percentage × (1 - reserve percentage) |
| Base assist draw | Eco 8, Tour/Auto 12, High 18, or throttle/minimal pedaling 24 Wh/km |
| Total system weight | Multiplier = clamp(0.80, 1.50, 1 + 0.004 × (kg - 120)) |
| Average speed | Multiplier = clamp(0.80, 1.80, 1 + 0.025d + 0.0015d²), where d is km/h minus 20 |
| Wind | Headwind multiplier = clamp(0.80, 1.55, 1 + 0.018w); tailwind = clamp(0.80, 1.55, 1 + 0.01w), with tailwind stored as negative |
| Temperature | Neutral from 15-25°C; demand rises 1.2% per degree below 15°C and 0.8% per degree above 25°C |
| Climbing | Mass × 9.80665 × gain per km ÷ (3600 × 0.78), multiplied by an assist motor share from 0.45 to 0.95 |
| Consumption boundaries | Typical consumption is kept between 5 and 44 Wh/km. Demanding consumption cannot exceed 55 Wh/km. |
| Range bands | Best conditions use 0.85× typical consumption. Demanding conditions use 1.25× typical consumption. |
| Low usable energy | Estimates with 100 Wh or less after battery health and reserve receive an additional low-energy warning. |
Supported inputs and display boundaries
Input domain
- Battery capacity: 200-1,500 Wh
- Estimated battery health: 50-100%
- Planned reserve: 5-40%
- Total system weight: 50-300 kg (111-661 lb)
- Average assisted speed: 8-45 km/h (5-27 mph)
- Elevation gain: 0-50 m/km (0-264 ft/mi)
- Wind: 20 km/h tailwind to 30 km/h headwind
- Ambient temperature: -10 to 40°C (14-104°F)
Conservative display
- Below 10 km, distance rounds down to a whole kilometre.
- From 10 to 24 km, distance rounds down by 2 km.
- At 25 km and above, distance rounds down by 5 km.
- Imperial labels come from the rounded metric value, not a fresh calculation.
- 250+ km (155+ mi) means the result is outside the calculator's display scope.
Worked examples
| Scenario | Main inputs | Best / typical / demanding |
|---|---|---|
| Reference commuter | 500 Wh, full health, 15% reserve, Tour/Auto, 120 kg, 20 km/h, 5 m/km gain, calm, 20°C | 35 / 30 / 25 km |
| Heavy, hilly, cold headwind | 750 Wh, 90% health, 20% reserve, High, 180 kg, 28 km/h, 20 m/km gain, 15 km/h headwind, 5°C | 14 / 12 / 9 km |
| Light, flat Eco ride | 320 Wh, 80% health, 25% reserve, Eco, 85 kg, 15 km/h, no climbing, 10 km/h tailwind, 20°C | 35 / 30 / 25 km |
What the model does not know
Range is an estimate, not a safety margin. Nameplate watt-hours and the battery display may not match energy available on a ride. Keep the reserve you entered and follow the bike and battery manual.
- Tires and pressure, surface, stops, cadence, rider effort, motor and controller efficiency, battery temperature, and maintenance are not modeled directly.
- Elevation is cumulative gain per distance, not maximum grade. Descending does not add regenerative energy because many e-bikes cannot regenerate.
- The bands describe broad planning conditions. They are not confidence intervals and do not predict one exact trip.
- This tool does not check battery, charger, motor, controller, firmware, or replacement-part compatibility.
Sources and attribution
These sources were checked on August 23, 2026. They support which factors belong in a range estimate, not BikeSize's numerical coefficients.
- Bosch eBike Systems Range Calculator
Factor selection: battery, support, speed, weight, terrain, wind, and temperature.
- Bosch eBike Battery Guide, 2021 edition
Explains why support, speed, weight, starts, temperature, tire pressure, and topography affect range.
- Trek Electric Bike FAQ
Manufacturer guidance on the broad factors that change real-world range.
- Specialized Turbo Range Calculator
Confirms that model-specific estimates use battery, support, weight, speed, temperature, and elevation.
- Shimano STEPS FAQ and technical documents
Battery capacity, assist mode, and temperature guidance are specific to each system and manual.
- Grin Technologies Trip Simulator
A more detailed technical reference for mass, grade, wind, speed, drag, rolling resistance, and electrical losses.
Shimano's full technical document library is available at si.shimano.com.
Frequently Asked Questions
Related Guides
Bike Size Guide for New Cyclists & Beginners
New to cycling? Find your perfect bike size with our beginner guide. Learn about inseam measurement, standover height, and how to choose your first bike.
Terrain-first eMTB buying and sizing guide
A source-backed eMTB decision guide that starts with terrain, then checks travel, motor support, battery, range, fit, and sizing.
How to Choose the Right Bike for You
Compare bike categories side by side, then check fit, purchase-day checks, and essential gear before choosing your next bike.