Electric Aircraft Range Calculator

Estimate electric aircraft range from battery energy and cruise power

Electric aircraft range is ultimately an energy budgeting problem: how much usable battery energy you can spend on propulsion, how quickly you spend it in cruise (power draw), and how fast you travel while spending it (cruise speed). This calculator provides a first‑order range estimate by assuming steady, level cruise at constant power and speed, then converting battery energy into cruise endurance and distance.

What this calculator does (and what it does not)

It does: convert battery capacity (kWh) into usable energy after a reserve, compute cruise endurance (hours) from cruise power (kW), and multiply by cruise speed (km/h) to estimate range (km).

It does not: model climb/descent, winds, temperature effects, battery voltage sag, propeller efficiency changes, or mission segments (taxi, takeoff, climb, loiter). Use this as a screening tool for early sizing, feasibility checks, and quick trade studies—not as a certified flight planning method.

Inputs and units (quick guidance)

• Battery Capacity (kWh): total stored electrical energy. If you only know battery pack voltage (V) and capacity (Ah), approximate: kWh ≈ (V × Ah) / 1000.
• Cruise Power Requirement (kW): the electrical power drawn during steady cruise (including motor/controller losses if your number is “from the battery”). If your value is shaft power, real battery power may be higher.
• Cruise Speed (km/h): true airspeed in cruise (TAS). Ground speed will differ with wind.
• Energy Reserve (%): portion of battery held back for contingencies. This calculator subtracts it from capacity before computing endurance.

Formulas used

Let:

• E = battery capacity (kWh)
• r = reserve fraction (%)
• P = cruise power draw (kW)
• v = cruise speed (km/h)

Usable energy and endurance:

• Usable energy, E_usable = E × (1 − r/100)
• Endurance (hours), t = E_usable / P

Range:

• Range (km), R = t × v = (E × (1 − r/100) / P) × v

MathML version:

Interpreting the result

The output is a simplified cruise-only range estimate. If the result is 120 km, it means that—under the stated assumptions—the aircraft could cruise for long enough to cover about 120 km before reaching the chosen reserve threshold. In practice:

• Headwinds reduce ground range; tailwinds increase it (even if airspeed is unchanged).
• Higher cruise power (due to weight, drag, or inefficient propulsion) reduces endurance and range.
• Higher cruise speed increases distance per hour, but often comes with higher power demand in real aerodynamics. Because this calculator treats power as an independent input, you should enter a power number consistent with the chosen speed.

Worked example

Suppose an electric aircraft has:

• Battery capacity E = 120 kWh
• Reserve r = 20%
• Cruise power P = 60 kW
• Cruise speed v = 150 km/h

Step 1: usable energy

E_usable = 120 × (1 − 0.20) = 96 kWh

Step 2: endurance

t = 96 / 60 = 1.6 hours

Step 3: range

R = 1.6 × 150 = 240 km

So the calculator would report an estimated cruise range of about 240 km under these simplified conditions.

How different inputs affect range (comparison table)

The table below illustrates the sensitivity of range to reserve and cruise power for a fixed battery and speed (E = 120 kWh, v = 150 km/h). Values are approximate and assume constant power in cruise.

Assumptions and limitations

• Steady cruise only: assumes constant cruise power and constant cruise speed in level flight.
• Reserve treatment: reserve is modeled as a simple percentage of total battery capacity removed from usable energy.
• No mission segments: excludes taxi, takeoff, climb, approach, and landing energy—often significant for short missions.
• No wind modeling: uses cruise speed as if it were ground speed; real routes depend on wind and headings.
• No temperature/degradation effects: battery usable capacity may be lower due to cold weather, aging, high discharge rates (C‑rate), or BMS limits.
• Power-speed consistency is user-provided: aerodynamic power typically rises strongly with speed; ensure the cruise power input corresponds to the chosen cruise speed.
• Not for operational flight planning: always follow aircraft documentation, regulatory reserve requirements, and approved performance data.

Practical tips

• If you have “battery energy available” after BMS limits, enter that as capacity and set reserve to 0% (or keep reserve as an additional safety margin).
• When comparing designs, keep reserve consistent so you can make apples-to-apples tradeoffs.
• If you want a conservative estimate, increase cruise power slightly and increase reserve.