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Free Vector Projection Calculator

Calculate the projection of one 2D vector onto another, including the scalar and vector projection.

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The projection of one vector onto another answers a simple geometric question: how much of vector A points in the same direction as vector B? It's a foundational operation used throughout physics, engineering, and computer graphics.

This calculator finds both the scalar projection (a single number) and the vector projection (a full 2D vector) of vector A onto vector B, with a complete step-by-step solution.

How it works

Enter the x and y components of vectors A and B. The calculator computes the dot product of A and B, divides by the magnitude of B to find the scalar projection, and scales vector B by the appropriate factor to find the full vector projection.

  1. Enter vector a — x (vector to project).
  2. Enter vector a — y.
  3. Enter vector b — x (direction to project onto).
  4. Enter vector b — y.
  5. Click Calculate to see your results.

Examples

Projecting (3, 4) onto (5, 0)

Projecting vector A = (3, 4) onto vector B = (5, 0) (which points purely along the x-axis) gives a scalar projection of 3 and a vector projection of (3, 0) — exactly A's x-component, since B points straight along the x-axis.

Who should use it

  • Finding the component of a force acting along a specific direction in physics problems.
  • Computing shadow/projection effects in computer graphics and game development.

Industry applications

  • Physics and engineering education
  • Computer graphics and game development

Advantages

  • Calculates both the scalar and full vector projection in one step.
  • Includes a complete, formula-based step-by-step solution.

Limitations

  • Limited to 2D vectors — 3D vector projection requires an extended formula.

Common mistakes to avoid

  • Confusing the scalar projection (a number) with the vector projection (a vector) — they answer related but different questions.
  • Forgetting that the order matters: projecting A onto B is generally different from projecting B onto A.

Best practices

  • Use the scalar projection when you just need a single "how much overlap" number, and the vector projection when you need the actual resulting vector for further calculations.

Tips

  • If you only need the "how much overlap" number and not the resulting vector, the scalar projection alone is usually simpler to work with.

Frequently asked questions

Yes, with no signup and no limit on how many calculations you run.
The scalar projection is a single number representing how far A extends in B's direction; the vector projection is the actual vector that results from scaling B by that amount — it points in B's direction with a length equal to the scalar projection.
A negative scalar projection means vector A points at least partly in the opposite direction of vector B (the angle between them is greater than 90 degrees).
No — projecting onto a zero vector is undefined, since a zero vector has no direction to project onto.

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