Speed Distance Time Calculator

Speed Distance Time Calculator – From Basic v = d/t to Full Motion Analysis

This Speed Distance Time Calculator is built to be a complete motion toolkit. At its core is the classic relationship v = d/t: speed equals distance divided by time. Around that core, the calculator adds distance and time solvers, unit conversions, pace calculations, average speed over multiple segments, ETA estimation, relative motion and constant-acceleration kinematics.

Instead of juggling multiple small tools, you can stay on a single page and switch tabs between everyday travel planning, fitness pacing and physics-style motion problems. All modes share a consistent approach to units and formulas, so you can trust that results match the underlying mathematics.

The Core Relationships: v = d/t, d = v × t, t = d/v

Any straight-line motion with constant speed can be described by three algebraically equivalent formulas:

Here:

• v is speed or velocity magnitude
• d is distance travelled
• t is elapsed time

These formulas are used in the Speed / Distance / Time tab. When you choose which variable to solve for, the calculator rearranges these relationships internally, converts all values to base units (metres and seconds), performs the calculation and then converts back to your requested units such as km/h, mph or minutes.

For example, if you travel 150 kilometres in 2 hours, your average speed is:

The SDT tab lets you enter these values directly and instantly see the result, along with equivalent speeds such as metres per second or miles per hour.

Unit Handling and Internal Conversions

Real-world problems rarely come in pure SI units. You might know distance in miles and time in minutes, or speed in km/h but want an answer in m/s. To keep calculations correct, the calculator performs a consistent unit conversion step internally.

For distance, it uses relationships such as:

• 1 km = 1000 m
• 1 mile ≈ 1609.344 m
• 1 ft ≈ 0.3048 m

For time, it uses:

• 1 minute = 60 seconds
• 1 hour = 3600 seconds
• 1 day = 24 hours

For speed, it uses:

• 1 km/h ≈ 0.27778 m/s
• 1 mph ≈ 0.44704 m/s
• 1 knot ≈ 0.514444 m/s

Every calculation is done in metres and seconds, and only at the final step are results converted back to your chosen display units. This avoids hidden inconsistencies and makes it easy to compare results across different sections.

Using the Speed / Distance / Time Solver

The SDT solver is your starting point when you want a direct application of v = d/t. It supports solving for any one of the three variables when the other two are known.

Solving for Speed v

If you know distance and time, the formula is:

Enter distance and time, select Solve for = Speed, and the calculator returns v in the speed unit you choose. For instance, if you drive 200 km in 2.5 hours:

Solving for Distance d

If you know speed and time, use:

For example, jogging at 10 km/h for 0.75 hours (45 minutes) covers:

Solving for Time t

If you know distance and speed, use:

Driving 90 km at 60 km/h takes:

The SDT tab automates these rearrangements and keeps the units consistent, so you can freely mix kilometres, miles, hours and minutes as inputs.

Pace and Average Speed for Running, Cycling and Walking

In fitness, you often think in terms of pace rather than speed. Pace measures how long it takes to cover each kilometre or mile, while speed measures how many kilometres or miles you cover per hour. The two are inversely related: higher speed corresponds to lower pace (fewer minutes per kilometre).

If total time is T and total distance is D, then:

In the Pace tab, you enter distance, hours, minutes and seconds. The calculator converts everything to seconds and kilometres, then finds:

• Pace per kilometre = T / D_km
• Pace per mile = T / D_mi
• Average speed in km/h and mph

For example, suppose you run 5 km in 25 minutes. Total time is 1500 seconds, distance is 5 km. Pace per km is:

Average speed is:

The calculator performs these conversions and formats pace as minutes and seconds for better readability.

Unit Converters for Speed, Distance and Time

The dedicated Unit Converters tab allows you to convert values even when you are not solving a full SDT problem. It includes three mini-tools.

Speed Converter

Enter a speed in one of the supported units and instantly see equivalents in m/s, km/h, mph and knots. Behind the scenes, all conversions pass through m/s to ensure consistency. This is useful when comparing travel speeds, treadmill settings, GPS readouts or technical specifications.

Distance Converter

The distance converter handles metres, kilometres, miles and feet. It is handy when combining road distances, GPS coordinates and engineering measurements in the same calculation.

Time Converter

The time converter moves between seconds, minutes, hours and days. This is often needed when you have durations given in mixed forms, such as “2 hours 30 minutes”, and want to express everything in a single unit like hours or seconds for a formula.

Average Speed Over Multiple Segments

Real trips are rarely a single constant-speed leg. You might crawl through traffic, cruise on an open highway, and slow down near your destination. The overall average speed for the whole trip is not just the average of your segment speeds; it is total distance divided by total time.

If a trip has segments i = 1 to n with distances d_i and times t_i, then:

The Average Speed tab in the calculator lets you enter an arbitrary number of segments, each with its own distance and time units. It converts distances to metres and times to seconds, sums them and reports:

• Total distance in kilometres and miles
• Total time in hours and minutes
• Average speed in m/s, km/h and mph

This is valuable when analyzing journey logs, training runs with varying intensity, or delivery routes with multiple stops.

ETA – Travel Time and Arrival Time

Estimated time of arrival (ETA) is a direct application of t = d/v. If you know how far you still have to travel and how fast you plan to go, the travel time is:

The ETA tab uses this travel time in two ways:

• As a plain duration, formatted as hours and minutes
• Added to an optional start clock time, such as 14:30, to give an arrival clock time

For example, if you have 120 km left and expect to average 80 km/h, your travel time is 1.5 hours, or 1 hour 30 minutes. Starting at 14:30, the estimated arrival time is roughly 16:00, ignoring stops or delays. The calculator handles this clock arithmetic by converting the start time to minutes after midnight, adding the travel minutes and wrapping around after 24 hours if necessary.

Relative Motion – Two Objects Moving at Once

Relative motion problems involve two moving objects, such as cars, trains or aircraft. The key idea is relative speed, which combines their individual speeds depending on direction.

If two objects move in opposite directions along the same line, their relative speed is the sum of their speeds:

If two objects move in the same direction, one chasing the other, the relative speed is the difference of their speeds:

If they start some distance apart with separation d and move toward each other (or one catches up with the other), the time to meet is:

The Relative Motion tab allows you to select opposite or same-direction chasing, enter each speed and an optional separation distance, and then computes both relative speed and time to meet when closing is possible. All units are converted to metres and seconds internally to ensure correctness.

Constant Acceleration – Extending Beyond Constant Speed

Many physics problems involve changing speed rather than constant-speed motion. Under constant acceleration in a straight line, three key kinematics formulas apply:

Here:

• u is initial speed
• v is final speed
• a is constant acceleration
• t is time
• d is distance travelled during the acceleration

The Acceleration tab provides three modes built from these equations.

Mode 1: Given u, a, t → v and d

In this mode you supply initial speed u, constant acceleration a and time t. The calculator uses:

This is ideal for problems like a car that accelerates from a given speed at a steady rate for a known time and you want to know both its final speed and how far it has travelled.

Mode 2: Given u, a, d → v and t

When distance is known instead of time, the calculator can use the equation that connects u, v, a and d without t:

Taking the square root gives v. With u, v and a known, the time t follows from:

This mode is useful when you know how far an object travels while accelerating and want to know its final speed and how long the acceleration lasted.

Mode 3: Given u, v, t → a and d

If you know the initial speed, final speed and time, the acceleration can be found as:

With u, v and t known, the distance d can be computed using the average speed over the interval:

The calculator applies these formulas and reports all quantities in SI units: speeds in m/s, acceleration in m/s², distance in metres and time in seconds.

Choosing the Right Mode for Your Problem

With many tabs and formulas available, it helps to have a quick mental checklist for which mode to use:

• If speed is constant and you simply want one missing piece, start with the SDT tab.
• If you care about fitness pacing, use the Pace tab for pace and average speed based on distance and total time.
• If your question is primarily about transforming units, use the Unit Converters tab.
• If your trip has varying segments and you want one overall average speed, use the Average Speed tab.
• If you are planning arrival times given a planned speed, use the ETA tab.
• If two vehicles interact (approaching or chasing), choose the Relative Motion tab.
• If speed is changing steadily under constant acceleration, switch to the Acceleration tab.

In each case, think about which quantities are known and which are unknown. Then pick the tool whose formulas match that pattern.

Checking Your Intuition and Avoiding Common Mistakes

Even a simple formula like v = d/t can lead to errors if units are mixed or if average speed is confused with average of speeds. The calculator helps by enforcing consistent units, but it is still important to check whether the result makes sense.

A few guidelines:

• If you double the distance with the same speed, time should double.
• If you double the speed for the same distance, time should be halved.
• If your pace per kilometre is lower, your speed must be higher, and vice versa.
• Average speed over multiple segments is not simply the mean of the segment speeds; it depends on how long you spend at each speed.
• When acceleration is positive, final speed should exceed initial speed; when it is negative, final speed should be lower.

If an output contradicts these expectations, recheck your inputs and units. The calculator can show you the arithmetic, but intuition helps you interpret the numbers correctly.