---
title: "Constant Rate — AP Calculus Definition & Exam Guide"
description: "A constant rate is a rate of change that stays the same over time, making the function linear, its derivative a fixed number, and its second derivative zero."
canonical: "https://fiveable.me/ap-calc/key-terms/constant-rate"
type: "key-term"
subject: "AP Calculus AB/BC"
---

# Constant Rate — AP Calculus Definition & Exam Guide

## Definition

A constant rate means that the value of the rate does not change over time. In this context, it means that the temperature is decreasing at a steady pace without speeding up or slowing down.

## Review

### Related Terms

- [Average Rate of Change](/ap-calc/key-terms/average-rate-of-change): The average rate of change measures the total change in a function divided by the total time taken for that change. It's different from a constant rate because it can include periods of acceleration or deceleration.
- [Linear Function](/ap-calc/key-terms/linear-function): A linear function has a constant rate of change, meaning its slope remains consistent throughout its domain.
- [Slope](/ap-calc/key-terms/slope): When analyzing linear functions, slope represents the constant rate at which one variable changes with respect to another variable.