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Ebike Range and Battery Size Estimator

Reviewed for 2026, updated September 8, 2026.

Estimates real-world range from a battery capacity, rider weight, assist level and terrain, and tells buyers how many watt hours they need for the rides they actually plan to do.

Your numbers

Results update as you type.

Your estimate

Estimated range...
Energy use...
Battery needed for target range...
Cost of a full charge...

Estimates only. Assumptions are listed below, and you can change every input.

Manufacturer range claims for electric bikes are usually quoted for a light rider on flat ground in the lowest assist mode, which is not how most people ride a 6,000 USD bike. The difference between the brochure figure and what you get on a hilly commute in sport mode can easily be a factor of two, and it decides whether you need a 500 Wh, 750 Wh or dual battery setup.

This estimator starts from a baseline energy use per mile, then scales it for your assist level, the terrain you ride and the total weight the motor has to move. It keeps 10 percent of the rated capacity in reserve, because most battery management systems cut power before a pack is truly empty. From that it reports the range you can expect, the watt hours you would need for a target ride, and what a full charge costs at your electricity rate.

How to use this tool

  1. Enter the battery capacity in watt hours from the spec sheet and your weight with gear.
  2. Choose the assist level and terrain that describe most of your riding, then set the range you want on a single charge.
  3. Compare the estimated range with your target and use the battery needed figure to decide between pack sizes or a dual battery option.

What the math assumes

  • Assumes a baseline of 15 Wh per mile for a 180 lb rider in Tour mode on rolling terrain, before adjustments; this is a modeling starting point, not a measured benchmark.
  • Assist multipliers are 0.6 for Eco, 1.0 for Tour, 1.4 for Sport and 1.9 for Turbo; terrain multipliers are 0.85 for flat, 1.0 for rolling and 1.35 for hilly.
  • Energy use scales with total moving mass, assuming the bike itself weighs 55 lb; a heavier cargo or full suspension bike will use more.
  • Only 90 percent of the rated capacity is treated as usable, to reflect the reserve most battery management systems keep and mild aging of the pack.
  • Charging from empty is assumed to draw 10 percent more energy from the wall than the pack stores, to cover charger losses; wind, temperature and tire pressure are not modeled.

Frequently asked questions

Why is my estimate lower than the manufacturer range claim?

Brochure figures are typically measured with a light rider, flat ground and the lowest assist setting. This estimator applies your actual weight, terrain and assist mode, which is why it often lands well below the advertised maximum.

How much battery should I buy for a daily commute?

Set the target range to your full round trip plus a margin of 20 to 30 percent for cold weather and headwinds. The battery needed output tells you the watt hours that would cover it in your usual mode.

Does a bigger battery always mean more range?

Yes for the same bike and rider, but it also adds weight and cost. If the estimate shows a smaller pack already covers your longest ride, the extra capacity mostly buys peace of mind rather than daily benefit.

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