About
Physics-first range prediction for electric bikes
E-Bike Range Calculator uses real physics — not rule-of-thumb estimates — to tell you how far your bike will go before the battery runs out.
Method
How the Calculator Works
Most e-bike range tools divide battery capacity by average watt-hours per kilometre and call it done. That works on flat ground with no wind at constant speed — conditions that almost never apply in the real world. Our calculator models the actual physics of cycling.
Aerodynamic drag and wind
Drag force scales with the square of velocity, so riding at 25 km/h takes roughly twice the energy of 18 km/h. We calculate drag from your CdA (drag coefficient × frontal area), which varies by riding position and bike type. A 20 km/h headwind is not symmetric with a 20 km/h tailwind — we model the actual vector addition of wind and rider velocity.
Elevation and rolling resistance
Climbing 100 metres of elevation requires approximately 9.8 kJ of mechanical energy per kilogram of total system weight, integrated over your full GPX route. Terrain surface, tire type, and pressure all affect how much energy the tyres absorb: a gravel tire at 40 PSI on dirt costs 2–3× more rolling energy than a road tire at 90 PSI on tarmac.
Motor, battery and rider
Motor efficiency varies with load and speed, so we apply efficiency curves to convert mechanical power to electrical power drawn from the battery. Lithium batteries deliver less capacity in cold weather — below 5°C usable capacity typically drops 15–25%, below 0°C losses can reach 30–40%. The assist ratio changes how much the motor contributes vs. your legs: eco mode may draw 150–200 Wh/km, turbo on the same route 400+ Wh/km.
When you upload a GPX file, we analyse every metre of the route profile to compute a terrain-accurate prediction. Without GPX, you can enter average elevation gain manually for a good approximation.
Confidence
Accuracy and Limitations
The largest sources of real-world deviation are:
- Battery age — a 3-year-old battery may have 80–85% of its rated capacity. Enter your estimated current capacity, not the label value, for older bikes.
- Riding style variability — frequent hard acceleration (traffic stops, trail obstacles) can increase consumption by 20–30% vs. steady-state cruising.
- Motor calibration — assist sensitivity, motor cut-in speed, and throttle maps vary significantly between manufacturers and firmware versions.
- Accuracy
- 10–15%
- Typical prediction accuracy under good input conditions
- Variables
- 7
- Physics factors modelled: drag, elevation, rolling, wind, motor, temperature, assist
- Price
- Free
- No login required for the basic calculator
- Routes
- GPX
- Upload real route files for terrain-accurate predictions
Data
Brand and Model Database
The brand and model pages on this site compile published manufacturer specifications (battery capacity in Wh, motor power in W, weight, category) and run them through our range model to produce eco / normal / sport range estimates.
- Brands
- 5
- Manufacturers with published specs
- Models
- 10
- Bikes with eco / normal / sport estimates
- Source
- Manufacturer
- Published spec sheets, normalised
Manufacturer range claims are typically measured under optimal lab conditions (level road, slow speed, light rider, warm temperature). Our estimates reflect more realistic mixed-use riding conditions and are intentionally more conservative.
Supported brands include Bosch, Giant, and others available at ebike.futornyi.com/range/brand/.
Credits
Data Sources
The playground's GPX world is built from open geodata. These are the sources it relies on and the terms under which they are used.
- Terrain elevation — Mapzen Terrain Tiles hosted on the AWS Open Data Registry, compiled from 3DEP, SRTM, GMTED2010, ETOPO1, EU-DEM, ArcticDEM, CDEM, NRCan, GEBCO, Australia DEM and other national sources. Full list and licences: tilezen/joerd attribution.
- Map tiles — © OpenStreetMap contributors, available under the Open Database Licence.
- Weather — live wind and temperature from Open-Meteo (CC BY 4.0).
Contact
Questions about the calculator, model data, or methodology? Use the contact page to get in touch.