Updated on September 10th, 2025

Rate Of Change Calculator

Created By Jehan Wadia

Supported: +, -, *, /, ^, sin, cos, tan, ln, log, sqrt, abs, exp, π, e


Introduction

The Rate of Change Calculator helps you find how fast something changes over time. Rate of change tells you how much one thing changes when another thing changes. For example, if you drive 60 miles in 2 hours, your rate of change is 30 miles per hour. This shows how your distance changes as time passes.

In algebra, we use rate of change to understand slopes of lines and how graphs move up or down. To find rate of change, you divide the change in the output by the change in the input. Our calculator makes this math easy. Just enter your starting and ending values, and it will show you the rate of change right away. For related calculations involving percentages, try our Percent Error Calculator to measure accuracy in your measurements.

How to use our Rate Of Change Calculator

Enter two points to find how fast something changes between them. The calculator will show you the rate of change.

First X Value (x₁): Type the x-coordinate of your first point. This is the starting horizontal position on a graph.

First Y Value (y₁): Type the y-coordinate of your first point. This is the starting vertical position on a graph.

Second X Value (x₂): Type the x-coordinate of your second point. This is the ending horizontal position on a graph.

Second Y Value (y₂): Type the y-coordinate of your second point. This is the ending vertical position on a graph.

Understanding Rate of Change

Rate of change is a key math concept that tells us how fast something changes. It measures how much one thing changes when another thing changes. Think of it like finding out how steep a hill is or how fast a car speeds up. For physics applications involving motion and speed, check out our Acceleration Calculator or Free Fall Calculator.

What is Rate of Change?

Rate of change shows the relationship between two things that change together. When you have two points on a graph, the rate of change is the slope of the line connecting them. It answers the question: "How much does y change for each unit that x changes?"

Types of Rate of Change

There are two main types of rate of change. Average rate of change looks at the overall change between two points. It's like finding your average speed on a trip. Instantaneous rate of change looks at the exact rate at one specific point. It's like checking your speedometer at one moment while driving. When studying motion and energy changes, our Kinetic Energy Calculator can help you understand how energy relates to velocity.

Real-World Uses

Rate of change appears everywhere in daily life. In physics, it helps calculate speed and acceleration using tools like our Force Calculator. In economics, it shows how prices or costs change over time. In biology, it measures growth rates. Even when you check how much your savings account grows each month, you're using rate of change.

The Basic Formula

The basic formula for rate of change is simple: divide the change in y by the change in x. This gives you (y₂ - y₁) / (x₂ - x₁). A positive rate means things are increasing. A negative rate means they're decreasing. A zero rate means no change is happening.


Frequently Asked Questions

What does a negative rate of change mean?

A negative rate of change means the value is going down. When you move from left to right on a graph, the line goes down. For example, if temperature drops 10 degrees in 2 hours, the rate of change is -5 degrees per hour.

Can I use fractions in the calculator?

Yes! You can enter fractions like 1/2 or 3/4 in any input box. The calculator will convert them to decimals and calculate the rate of change. You can also use special values like π (pi) and e.

What's the difference between average and instantaneous rate?

Average rate measures change over a period of time, like your average speed on a whole trip. Instantaneous rate measures change at one exact moment, like your speed right now on your speedometer.

Why can't x₁ and x₂ be the same?

When x₁ and x₂ are the same, you would divide by zero in the formula. This is not allowed in math. You need two different x values to measure how things change between them.

How do I find rate of change from a graph?

Pick two points on the graph. Find their coordinates (x₁, y₁) and (x₂, y₂). Enter these four numbers into the calculator. The result shows how steep the line is between those points.

What functions can I enter in function mode?

You can use basic math (+, -, *, /), powers (^), and functions like sin, cos, tan, ln, log, sqrt, abs, and exp. Write multiplication as * (like 2*x instead of 2x).

How do I calculate percentage change?

Select 'Percentage Change' from the Result Type menu. The calculator will show how much the value changed as a percent. This is useful for finding percent increase or decrease.

What do the quick example buttons do?

The example buttons load sample problems to help you learn. Linear shows constant change. Quadratic shows curved change. Physics shows velocity. Economics shows cost changes. Try them to see how different rates work.