Close this search box.

Table of Contents

Long-Run Average Total Cost (LRATC)


Long-Run Average Total Cost (LRATC) is a concept in economics that represents the lowest average cost per unit of output that a firm can achieve when all factors of production are variable in the long run. It is calculated by considering the total cost over various levels of output and is obtained by dividing total costs by the quantity of output. The LRATC helps businesses determine the lowest cost at which they can operate efficiently in a sustainable manner.


Long-Run Average Total Cost (LRATC) is phonetically pronounced as: Lahng-Ruhn Av-er-ij Toh-tuhl Kost (El-Ar-Ay-Tee-Cee)

Key Takeaways

1. Economies of Scale: In the initial phases of production, as the output level increases, the Long-Run Average Total Cost (LRATC) generally falls. This is primarily due to the ability to spread fixed costs over a larger number of units and the increased efficiency gained with larger productive entities, which is known as tapping into the economies of scale.

2. Constant Returns to Scale: At some point, with further increases in output, LRATC ceases to decline and instead becomes relatively constant. This phase represents constant returns to scale, meaning the firm is achieving the optimal scale of production.

3. Diseconomies of Scale: If output continues to increase beyond the point of constant returns to scale, LRATC begins to rise, demonstrating the diseconomies of scale. This rise can be attributed to factors such as increased complexity and overhead costs that come with managing larger-scale operations.


The Long-Run Average Total Cost (LRATC) is an essential concept in business/finance because it reflects the cost of production when all factors of production are variable. It represents a firm’s minimum average cost per unit of output when it can fully adjust all inputs. The significance of LRATC lies in its role in determining the optimal scale of production that minimizes cost in the long term. This helps firms in strategic business decision-making and efficiency improvements. Furthermore, it reveals the nature of returns to scale in a firm’s production process. Therefore, understanding and analyzing LRATC is crucial for cost management, production planning, and overall business strategy in the realm of finance.


Long-Run Average Total Cost (LRATC) serves a critical role in understanding the financial dynamics of a business and is especially helpful in strategic decision-making processes. The most important application of LRATC is its ability to predict the potential benefits and drawbacks of expanding or downsizing a business in the long run. It helps businesses estimate how their overall costs will change when they adjust their output levels, thereby informing decisions about mergers, acquisitions, and investments. Economists and analysts observe the trends in the LRATC curve to decide whether it’s beneficial to maintain current production levels, or whether increasing or decreasing production would lead to reduced costs in the long run.LRATC is also used to identify the optimal scale of operations for a business. It provides a comprehensive overview of the cost efficiency of a company at various levels of output in the long-term. By considering LRATC, businesses can hold discussions about the most efficient balance between capital and labor, the best time to automate processes, and the effective way to use financial resources. Additionally, this principle functions as a guide during pricing decisions. By keeping track of how changes in production levels affect average total costs, companies can price their goods or services in a way that maximizes profits and sustains the business in the long term.


1. Manufacturing Firms: One of the most common examples of long-run average total cost (LRATC) exists within manufacturing plants. These firms often possess the ability to increase their scale of production, purchasing more machinery or renting additional factory space. When initially increasing their production, they may experience lower average total costs because of economies of scale. However, if the manufacturing plant grows too big, it may become inefficient and see a rise in the LRATC due to diseconomies of scale.2. Telecommunication Industry: Companies in this sector often involve considerable capital expenditures in the long-run like satellite launches, building signal towers and infrastructure, high tech equipment purchases, etc. In the beginning, spreading these high fixed costs over a large number of units (subscribers) would lower their LRATC, given the scale of economy. But beyond a certain point, managing the expansive network might increase the average cost, reflecting diseconomies of scale.3. Automobile Industry: Automobile companies often experience long-run average total cost changes. For example, if a car company invests heavily in cutting edge manufacturing technology, their average total cost may be quite high in the short term. But as they produce more cars, and improve efficiency over time, they can spread these initial costs over a larger number of units, reducing their long-run average total cost. However, if the production continues to expand indefinitely, efficiency of management and production might decrease, leading to an increase in LRATC.

Frequently Asked Questions(FAQ)

What is Long-Run Average Total Cost (LRATC)?

LRATC is a business and economics term that refers to the average per-unit cost of production over the long term, where all inputs are considered variable.

How is the Long-Run Average Total Cost (LRATC) calculated?

LRATC is calculated by dividing the total cost (both fixed and variable costs) by the total output produced in the long run.

How does the LRATC curve look like on a graph?

The LRATC curve is usually U-shaped on a graph, indicating that there are economies of scale at low levels of production and diseconomies of scale at high levels of production.

How does LRATC relate to the economies of scale?

The downward-sloping portion of the LRATC curve indicates economies of scale. It means that as a company increases its production volume, the cost per unit decreases.

What are the implications of LRATC for businesses?

LRATC is helpful for businesses to understand the cost-volume-profit relationship over the long term. It assists in long-term strategic planning, cost control, and pricing decisions.

Does the LRATC stay constant over time?

No, LRATC can change over time due to factors such as technology advancement, changes in input prices, and operational efficiency improvements.

Can the long-run average total cost (LRATC) ever increase?

Yes, if a business experiences diseconomies of scale, the LRATC can rise. This typically occurs when a firm’s production exceeds a certain level, resulting in managerial inefficiencies or higher costs of inputs.

Does the LRATC curve always touch the short-run average total cost (SRATC) curve?

Yes, the LRATC is the envelope of the SRATC curves, meaning it is tangent to, or touches, all points of the various possible short-run average total cost curves.

What is the importance of the minimum point on the LRATC curve?

The minimum point on the LRATC curve represents the lowest possible cost per unit of output that a firm can achieve in the long run. It is also the point of optimal production capacity.

Related Finance Terms

  • Economies of Scale: This refers to the cost advantages that an entity obtains due to the scale of output, with cost per unit of output generally decreasing with increasing scale.
  • Diseconomies of Scale: This refers to the situation where the cost per unit increases as the quantity of output increases, commonly arising due to difficulties in managing a larger workforce or inefficient operations.
  • Return to Scale: It demonstrates the change in output as all factors change by the same proportion. It explains the behavior of output relative to the change in inputs.
  • Production Function: This term has to do with the relationship between the quantity of inputs used in production and the quantity of output from production.
  • Cost Curve: A cost curve is a graph of the costs of production as a function of total quantity produced. It specifically refers to the graphical representation of Long-Run Average Total Cost (LRATC).

Sources for More Information

About Our Editorial Process

At Due, we are dedicated to providing simple money and retirement advice that can make a big impact in your life. Our team closely follows market shifts and deeply understands how to build REAL wealth. All of our articles undergo thorough editing and review by financial experts, ensuring you get reliable and credible money advice.

We partner with leading publications, such as Nasdaq, The Globe and Mail, Entrepreneur, and more, to provide insights on retirement, current markets, and more.

We also host a financial glossary of over 7000 money/investing terms to help you learn more about how to take control of your finances.

View our editorial process

About Our Journalists

Our journalists are not just trusted, certified financial advisers. They are experienced and leading influencers in the financial realm, trusted by millions to provide advice about money. We handpick the best of the best, so you get advice from real experts. Our goal is to educate and inform, NOT to be a ‘stock-picker’ or ‘market-caller.’ 

Why listen to what we have to say?

While Due does not know how to predict the market in the short-term, our team of experts DOES know how you can make smart financial decisions to plan for retirement in the long-term.

View our expert review board

About Due

Due makes it easier to retire on your terms. We give you a realistic view on exactly where you’re at financially so when you retire you know how much money you’ll get each month. Get started today.

Due Fact-Checking Standards and Processes

To ensure we’re putting out the highest content standards, we sought out the help of certified financial experts and accredited individuals to verify our advice. We also rely on them for the most up to date information and data to make sure our in-depth research has the facts right, for today… Not yesterday. Our financial expert review board allows our readers to not only trust the information they are reading but to act on it as well. Most of our authors are CFP (Certified Financial Planners) or CRPC (Chartered Retirement Planning Counselor) certified and all have college degrees. Learn more about annuities, retirement advice and take the correct steps towards financial freedom and knowing exactly where you stand today. Learn everything about our top-notch financial expert reviews below… Learn More