Calculate velocity three ways: find average velocity from distance and time, find final velocity from an initial velocity and constant acceleration, or find the weighted average velocity across several segments travelled at different speeds. Enter your values with any units and the calculator converts everything automatically.
The velocity calculator is a fast, flexible tool for solving the most common velocity problems in physics. Whether you need to work out how fast something is moving from the distance it covers, find the speed a car reaches after accelerating, or average out a trip made at several different speeds, this calculator handles it — and it converts freely between metric and imperial units so you never have to do the arithmetic by hand. Enter what you know, leave the unknown blank where the mode allows, and get an accurate answer instantly.
Velocity is one of the foundational concepts in mechanics, and understanding it unlocks a huge range of everyday and scientific problems, from planning a road trip to analysing the motion of a falling object. This page walks through exactly what velocity is, the formulas behind each mode of the calculator, worked examples you can reproduce, and answers to the questions people most often ask.
Velocity is the rate at which an object changes its position. In plain terms, it tells you how fast something is moving and in which direction. That direction component is what separates velocity from speed: velocity is a vector quantity (it has both magnitude and direction), while speed is a scalar quantity (magnitude only). A car travelling at 60 km/h due north has the same speed as a car travelling 60 km/h due south, but their velocities are different because they point in opposite directions.
The standard SI unit of velocity is the meter per second (m/s), though kilometers per hour (km/h) and miles per hour (mph) are far more familiar in daily life. This calculator lets you work in whichever unit is most convenient and shows the result across several units at once, so the number always makes intuitive sense.
The most basic definition of average velocity is displacement divided by the time taken:
velocity = distance ÷ time (v = d / t)
Here d is the distance (strictly, the displacement) travelled and t is the elapsed time. If a runner covers 100 meters in 10 seconds, their average velocity is 100 ÷ 10 = 10 m/s. Because the relationship is a simple ratio, you can rearrange it to find any of the three quantities when you know the other two:
The first tab of the calculator, Distance & Time, is built exactly around this. Enter any two of distance, time, and velocity, leave the third field blank, and it will be solved for you.
Suppose you walk 500 meters in 3 minutes and want your average velocity. First, convert the time to seconds: 3 minutes = 180 seconds. Then divide:
v = 500 m ÷ 180 s ≈ 2.78 m/s
That works out to about 2.78 m/s, or roughly 10 km/h — a brisk walking pace. These are the default values in the first tab, so you can press Calculate and see the full breakdown, including the equivalent speed in km/h, mph, and ft/s.
Objects rarely move at a perfectly steady speed. When something speeds up or slows down at a constant rate, its velocity changes over time according to:
final velocity = initial velocity + (acceleration × time) (v = v₀ + a·t)
where v₀ is the starting (initial) velocity, a is the acceleration, and t is how long the acceleration is applied. This is one of the classic equations of motion for uniformly accelerated motion. Acceleration is measured in meters per second squared (m/s²) — it tells you how many m/s the velocity gains every second.
The second tab, With Acceleration, applies this formula. It is perfect for questions like "how fast is a car going after accelerating for a few seconds?" or "what velocity does a dropped object reach after falling for two seconds?"
Imagine a car starting from rest (initial velocity = 0) that accelerates at 6.95 m/s² for 4 seconds. Its final velocity is:
v = 0 + (6.95 × 4) = 27.8 m/s ≈ 100 km/h
So after just four seconds it is travelling about 27.8 m/s, which is very close to 100 km/h — a respectable 0-to-100 time. These are the default values in the acceleration tab, ready for you to try.
Real journeys are made up of stretches travelled at different speeds — a fast section on the motorway, a slow crawl through town, and so on. To find the true average velocity of the whole trip, you cannot simply average the speeds; you must weight each speed by how long it was maintained. The formula is:
average velocity = (v₁t₁ + v₂t₂ + …) ÷ (t₁ + t₂ + …)
Each segment contributes its velocity multiplied by its time, and the sum is divided by the total time. This is a time-weighted average, and it is the correct way to combine velocities held for different durations. The third tab, Average of Segments, lets you add as many segments as you need, each with its own velocity and duration.
Suppose you drive at 10 m/s for 5 seconds, then at 20 m/s for 3 seconds. The weighted average velocity is:
v̄ = (10 × 5 + 20 × 3) ÷ (5 + 3) = (50 + 60) ÷ 8 = 13.75 m/s
Notice the answer, 13.75 m/s, is closer to 10 m/s than to 20 m/s, because more time was spent at the lower speed. A naive average of the two speeds would have given 15 m/s — the wrong answer. These are the default segments in the third tab.
The words "speed" and "velocity" are used interchangeably in everyday conversation, but in physics they mean different things:
A practical consequence: if you run one lap of a 400 m track in 80 seconds and end up exactly where you started, your average speed is 400 ÷ 80 = 5 m/s, but your average velocity is zero, because your displacement (the straight-line distance from start to finish) is zero. For motion in a straight line without reversing direction — the situation in most calculator problems — the magnitude of velocity and the speed are the same number, which is why this tool works well for both.
Velocity can be expressed in many units, and converting between them trips a lot of people up. The calculator handles it automatically, but it helps to know the key relationships:
Because the calculator lets you choose units independently for each input and for the result, you can, for example, enter a distance in miles and a time in hours and read the velocity straight off in m/s — no manual conversion required.
Velocity calculations show up almost everywhere once you start looking:
This calculator computes average velocity — the total displacement divided by the total time, or the time-weighted combination of segment velocities. Average velocity smooths out all the variations during the trip into a single representative figure. Instantaneous velocity, by contrast, is the velocity at one specific moment — the number your car's speedometer shows right now. Mathematically, instantaneous velocity is the limit of average velocity as the time interval shrinks toward zero, which is the derivative of position with respect to time in calculus. For most practical problems, average velocity is exactly what you want, and it is what the distance-and-time and segment modes provide. The acceleration mode goes one step further by giving you the exact (instantaneous) velocity at the end of a period of constant acceleration.
Average velocity equals distance divided by time: v = d / t. If an object travels 100 meters in 20 seconds, its velocity is 100 ÷ 20 = 5 m/s.
Use v = v₀ + a·t, where v₀ is the initial velocity, a is the acceleration, and t is the time. For an object starting from rest, v₀ is zero, so final velocity is simply acceleration multiplied by time.
Not exactly. Speed is how fast something moves (a scalar), while velocity also includes direction (a vector). For straight-line motion without reversing, their magnitudes are equal, which is why this calculator works for both.
Multiply the value in meters per second by 3.6. For example, 10 m/s × 3.6 = 36 km/h. To go the other way, divide km/h by 3.6.
Because the times spent at each speed usually differ. If you drive longer at the slower speed, the average leans toward it. You must weight each speed by its duration, which is exactly what the Average of Segments tab does.
Yes. Because velocity is a vector, a negative value simply means motion in the direction opposite to the one you chose as positive. Speed, by contrast, is never negative.
This Velocity Calculator is provided for general educational and informational purposes. It assumes idealized conditions — constant acceleration where applicable and straight-line motion — and does not account for factors such as air resistance or changing acceleration. For critical engineering or scientific work, verify results with appropriate methods and professional judgment.