Speed distance time basics

Speed distance and time are three ways to describe the same straight line motion. If you know how far something travels and how long it takes, you can compute the speed. If you know the speed and the time, you can find the distance, and so on.

In simple school and everyday problems we usually assume constant speed. That means the object covers equal distances in equal time intervals without speeding up or slowing down.

The calculator on this page keeps that relationship visible so that every answer is tied back to the same set of formulas.

Core formulas

The starting point for all constant speed questions is:

From this definition we can rearrange the formula to solve for each variable.

As long as units are consistent, these three formulas are enough to handle most basic travel and motion questions.

Units and conversions

The same physical motion can be described with many different units. For example a city trip can be described in miles per hour or kilometers per hour, and a sprint can be described in meters per second.

• Speed units: miles per hour, kilometers per hour, meters per second.
• Distance units: miles, kilometers, meters.
• Time units: hours, minutes, seconds.

Useful conversion facts include:

• 1 mile is 1.60934 kilometers and about 1609.34 meters.
• 1 hour is 60 minutes or 3600 seconds.
• 1 kilometer per hour is about 0.27778 meters per second.

The calculator converts all values internally so you can choose the units that feel most natural for your problem.

What this calculator shows

To keep the interface simple, the tool always works with the same three variables but lets you pick which one to solve for.

• The target variable, which can be speed, distance, or time.
• The two input values with their units.
• The result expressed in the selected unit along with an approximate decimal value.
• A short note reminding you which formula and unit conversion were used.

You can add each run as a scenario to the comparison table and keep a small history on your device for later review.

Worked examples

Here are a few example problems that you can try directly in the calculator.

• Example A, find speed:
  A car travels 150 kilometers in 2 hours. Distance is 150 kilometers and time is 2 hours, so speed is 150 ÷ 2 which is 75 kilometers per hour.
• Example B, find distance:
  A train moves at 90 kilometers per hour for 3 hours. Distance is speed multiplied by time, so distance is 90 × 3 which is 270 kilometers.
• Example C, find time:
  A runner keeps a pace of 5 meters per second and wants to cover 1000 meters. Time is distance divided by speed so time is 1000 ÷ 5 which is 200 seconds or a little over 3 minutes.
• Example D, mix of miles and hours:
  If a trip covers 180 miles in 3 hours, the average speed is 60 miles per hour. You can enter 180 miles and 3 hours directly and select miles per hour as the speed unit.

Typical uses beyond homework

The same simple formulas show up in many everyday settings.

• Estimating arrival times for car trips or public transport.
• Planning running or cycling pace for training sessions.
• Checking average speed from a travel log or GPS device.
• Turning time records from a track into average speeds for comparison.

In each case the calculator lets you switch between the three variables quickly without doing conversions by hand.

Limits and real world factors

In real life, speed is rarely constant. Traffic lights, hills, and changes in pace all cause variation over time.

• The calculator works with average speed, not every small change along the way.
• Short trips with stops may have a lower average speed than the speed shown on the dashboard.
• Rounding input values or results introduces small differences compared to high precision measurements.

For simple planning and homework the constant speed assumption is usually enough. For detailed motion analysis, more advanced tools are needed.

References

Speed overview | Distance basics | Time and measurement