What does this calculator assume?

Coplanar circular orbits and impulsive burns (instantaneous). It uses the standard Hohmann transfer ellipse between radii r1 and r2. Real missions include gravity losses, finite burn durations, and perturbations.

How is plane change handled?

If a plane change angle is provided, it is vector-combined with the circularization burn at apogee (for r2>r1) or at perigee (for r2<r1). This gives the correct single-impulse combined Δv at that node.

When is a bi-elliptic transfer better?

For very large radius ratios (r2/r1 ≳ 12), a bi-elliptic transfer can use less Δv than Hohmann. This tool focuses on classic Hohmann for simplicity.

Yes. All calculations run entirely in your browser.

Hohmann Transfer Calculator – Δv₁, Δv₂ & Time of Flight

Hohmann Transfer Calculator

Enter two circular orbits to get Δv₁, Δv₂, total Δv, and time of flight. Optionally combine a plane change with the circularization burn — all computed privately in your browser.

Inputs

Central body

Orbit units

Start orbit (h₁ or r₁)

Target orbit (h₂ or r₂)

Plane change at node (°) (optional)

Apply plane change with

Assumptions: circular, coplanar orbits (unless plane change specified); impulsive burns; central body point mass.

Results

Δv₁ (inject to transfer):

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Δv₂ (circularize):

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Total Δv:

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Time of flight (half-ellipse):

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Key speeds:

v₁ (circ), v₂ (circ), v at periapsis/apogee on transfer.

What this calculator does

For radii r₁ and r₂ around a body with parameter μ, the transfer ellipse has semi-major axis a = (r₁ + r₂)/2. Burn 1 sets the periapsis (or apogee) speed to enter the ellipse: v_t,1 = √(μ(2/r₁ − 1/a)). Burn 2 circularizes at r₂ with v_t,2 = √(μ(2/r₂ − 1/a)). Circular speeds are v_c,1 = √(μ/r₁), v_c,2 = √(μ/r₂). We report Δv₁ = |v_t,1 − v_c,1| and Δv₂ = |v_c,2 − v_t,2|. Time of flight is T = π√(a³/μ). If a plane change is specified, Δv₂ is vector-combined with the plane-change angle at the chosen node.

Hohmann Transfers: Why They Matter

A Hohmann transfer is the most energy-efficient two-impulse maneuver between two circular, coplanar orbits. It uses an elliptical transfer path whose periapsis lies at the inner orbit and apogee at the outer. Because the transfer ellipse is tangent to both orbits, the spacecraft changes speed only twice: once to enter the ellipse, and once to circularize at the destination.

The Core Equations

With starting radius r₁ and target radius r₂ around a body of gravitational parameter μ, the semi-major axis of the transfer ellipse is a = (r₁ + r₂)/2. The speeds on the transfer arc are v_t(r) = √( μ(2/r − 1/a) ). Circular speeds are v_c(r) = √( μ/r ). The burns are Δv₁ = |v_t(r₁) − v_c(r₁)| and Δv₂ = |v_c(r₂) − v_t(r₂)|. The time of flight for the half-ellipse is T = π√( a³/μ ).

Plane Changes

If an inclination change is needed, the cheapest time to apply it is where your speed is lowest (apogee for outward transfers; periapsis for inward). This tool lets you combine the plane change with the circularization burn using vector addition: Δv_combined = √( v_t,2² + v_c,2² − 2 v_t,2 v_c,2 cos Δi ). For small Δi, this reduces to ~2v sin(Δi/2).

Limitations

Real missions have finite burn durations, gravity/drag losses during thrusting, J2 and third-body effects, and operational constraints (lighting, ground station coverage, phasing). For very large radius ratios, a bi-elliptic transfer can beat Hohmann in total Δv. Still, Hohmann is the standard baseline for early design and education because it captures the essential energetics with simple closed-form equations.

Educational use only; not for mission-critical planning.