This velocity calculator solves the fundamental motion triangle — velocity, distance, time — for whichever variable you’re missing, with m/s, km/h and mph conversions on every result.

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Velocity vs Speed — the One Distinction That Matters

Velocity = displacement ÷ time, and displacement cares about direction: drive 100 km north in an hour and your velocity is 100 km/h north, however wiggly the road. Drive a full lap back to the start and your average velocity is zero while your average speed was anything but. For straight-line trips the two coincide, which is why everyday usage blurs them — our Speed Calculator handles the pure-magnitude version, and once velocity starts changing, you want the Acceleration Calculator. Part of our Physics Calculators collection.

Worked Example (Verified)

  • 100 km in 1.5 hours: velocity = 66.7 km/h = 18.5 m/s — the defaults above (100,000 m ÷ 5,400 s)
  • Unit intuition: highway 60 mph = 26.8 m/s: every second, three bus-lengths. Reaction-time math (0.25 s to perceive) is why following distances are measured in seconds.
  • Solving backwards: at 12 m/s (a strong cycling pace), 5 km takes 416.7 s ≈ 6 min 57 s — the “Time” mode.

Average vs Instantaneous

  • This calculator gives average velocity over the whole interval — traffic, stops and all.
  • Instantaneous velocity is the derivative (calculus) — the speedometer’s changing number. Physics problems switch between the two silently; check which yours wants.
  • Combine legs by total displacement ÷ total time — never by averaging the leg velocities unless the times are equal (the classic trap: 60 km/h out, 40 km/h back averages 48 km/h, not 50, because the slow leg lasts longer).

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Frequently Asked Questions

How do you calculate velocity?

Velocity = displacement ÷ time. 100 km in 1.5 h = 66.7 km/h (18.5 m/s). Include a direction to be fully correct — velocity is a vector; speed is its magnitude alone.

How do I convert m/s to km/h or mph?

m/s × 3.6 = km/h; m/s × 2.237 = mph. Reverse: km/h ÷ 3.6, mph ÷ 2.237. A 100 m sprint in 10 s is 10 m/s = 36 km/h — world-class humans briefly outrun city traffic.

Why is my average velocity zero on a round trip?

Displacement is start-to-end change of position; returning to the start makes it zero, however far you traveled. Your average speed (total distance ÷ time) captures the trip honestly — the distinction is physics’ way of asking “did you end up anywhere?”

What is terminal velocity?

The falling speed where air resistance balances gravity, so acceleration stops: ~53 m/s for a spread-eagle skydiver, ~90 m/s in a dive, about 9 m/s for a raindrop (which is why rain doesn’t wound).

Can velocity be negative?

Yes — sign encodes direction relative to your chosen axis. Negative velocity means moving opposite the positive direction; a negative speed is meaningless. Most confusion in homework is axis confusion, not math error.

Is this velocity calculator free?

Yes — free, instant, no sign-up.