Demand Forecasting: How to Calculate Demand Step by Step

Written by
Felipe Hernández
August 18, 2026
20 min of reading
Demand Forecasting: How to Calculate Demand Step by Step
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If your goal is to grow profitably, you need to know how to run a proper demand forecast for your company.

Demand forecasting lets you understand how your market will behave, so that based on that data you can align your strategic areas and adjust your operations, from procurement and suppliers to distribution to your customers.

Here we share the key things to keep in mind about how to project demand for products or services.

What is demand forecasting? Definition and meaning

Demand is the quantity of a product or service that consumers are willing to buy at a given price, in a given period. In economics it is expressed as a relationship between price and quantity demanded; in your operation it is expressed in units per SKU, channel and location.

Demand forecasting is the data-based estimate of how many units you will sell per period, channel and location. It analyzes the number of products or services that consumers are willing to buy across the different combinations or hierarchies of your company, which may include different locations, channels, prices and other market conditions.

Why is demand forecasting important?

Because a reliable projection translates into money. By collecting information about the behavior of your consumers and calculating the demand for a product or service, your company will be able to know the needs and expectations of its customers, understand the competition, identify high and low seasons, and understand what situations affect the sales of a specific product.

🚀 To complete your reading: How to make a sales forecast

Types of demand

At the economic level, there are different types of demand in the market. These are the most important ones:

Direct demand

The simplest type of demand, where you identify how many people are planning to buy a product.

Example of direct demand: 5,000 people fill in a form for the pre-sale of a mobile phone. Each registration represents an explicit purchase intention, so the manufacturer can estimate an initial direct demand of 5,000 units.

Indirect demand

Related to products that are necessary for the manufacture of others. If demand for the final product increases, the one used for its manufacture will also be affected.

Example of indirect demand: Electric car sales rise in a country. As a consequence, demand for charging stations goes up. Building those stations requires high-power chargers, connectors, heavy cabling, transformers and the software that controls them. Demand for charging cars indirectly pushes demand for every one of those components.

Latent demand

Here it is not possible to meet the demand for a product or service because the consumer is unaware that the solution exists, cannot afford it, or the product is simply not available.

Example of latent demand: Before ride-hailing services like Uber existed, millions of people needed flexible door-to-door transport but did not know an app could solve it. The need was there (latent), but the solution was neither visible nor accessible.

Joint demand

If two products complement each other or are directly related, they affect each other's demand.

Example of joint demand: Capsule coffee machines and compatible capsules. When machine sales rise, capsule demand rises with them, because the main product depends on the complementary consumable.

Irregular demand

This varies unpredictably over time, whether due to fashion trends, events or seasonal factors.

Example of irregular demand: An unexpected storm sends people running to the shops and umbrella sales spike within hours. When good weather returns, sales collapse again. Because those peaks rise and fall without a stable pattern, this is irregular demand.

Negative demand

Appears with products or services that potential consumers actively tend to avoid.

Example of negative demand: Dental visits. Many people avoid going out of fear of pain, anxiety, bad memories or perceived cost. The service exists and the need is real (oral health), yet patients actively refuse to book until the problem is severe.

Full demand

When demand is equal to or greater than the production or supply capacity of a product or service.

Example of full demand: A plant can produce 10,000 pairs of shoes a month and receives confirmed orders for 10,000–10,500 pairs monthly on a sustained basis. Demand absorbs the entire capacity, or slightly exceeds it, keeping the operation running at full capacity.

Overfull demand

Occurs when demand is greater than the supply available in a market.

Example of overfull demand: A batch of 50,000 tickets goes on sale for a stadium concert, but 200,000 fans try to buy. Tickets sell out in minutes and thousands are left unserved. Demand exceeds available supply in the short term.

Excessive demand

Demand is also higher here, but at a level that is neither healthy nor sustainable for society.

Example of excessive demand: During a crisis, people buy and hoard infant formula or toilet paper far beyond their real needs. This does not just exceed supply; it creates shortages for others, distorts prices and can require rationing or regulatory intervention.

Information to consider in a demand analysis

To forecast market demand and run demand planning, there are multiple variables to consider, since clear and reliable results are the goal. To achieve that, you also need to consider supply.

We therefore recommend that you consider the following information:

Factors affecting supply

The key information about supply consists of 4 aspects, which your company must always be very clear about in order to achieve sustainable growth:

  • Price: The price factor is fundamental because if it increases, the supply of the product or service will also increase, because producers will be more willing to participate in the market.
  • Competitive or joint supply: Two particular cases arise here. On the one hand, if a competitor switches manufacturing from one product to another, the one that has been replaced becomes less profitable. In the case of joint supply, it occurs when a price increase in one product affects another.
  • Cost of production: If production costs increase, supply is reduced, since manufacturing becomes less profitable.
  • Variation in resource availability: when a product that serves as a raw material becomes scarce, it becomes more difficult to produce, so supply decreases.

Factors affecting demand

When it comes to factors that impact the demand for a product or service, there are a number of aspects that all companies must take into consideration, such as:

  • Purchasing power of the target audience: not all people have the same level of income, nor the ability to buy any type of product or service. This aspect must be well identified in your company.
  • Preferences and tastes of your audience: a company must understand the needs of its consumers; this brings you closer to them.
  • Prices of complementary or similar products: demand for your product will be affected by the prices of products related to yours, whether substitutes or complements. This is because consumers tend to evaluate the whole environment.
  • Volume of potential customers: identify whether your company has niche products or, on the contrary, products for mass consumption.

How to forecast demand step by step: the 4-step method

Below we share the steps you must follow to calculate demand for a product or service, in order to understand the quantity consumers would be willing to purchase and thus better understand the market to achieve profitable growth.

1. Data collection

Being able to define what your data sources are and how you will access them in order to process them is the first step when you are preparing to analyze the demand for a product.

Historical data

Examine your historical demand to understand patterns and trends. The amount of time to consider will depend on the technique you want to use.

Remember that demand is the relationship between orders received and products invoiced. If you are not properly tracking your stockouts, you need to find a way to capture that information — without it you are not calculating demand, you are calculating sales.

Generally, the basis for calculating the demand for products or services can be found in the ERP (Enterprise Resource Planning).

Other internal data sources

The acceleration of the digital transformation process has led companies to acquire new tools for their sales and supply chain, such as WMS (Warehouse Management System), MRP (Material Requirements Planning), TMS (Transportation Management System) and CRM (Customer Relationship Management), among others.

You should consider the tools that can help you get a much more accurate demand calculation, depending on how you have defined your process.

External data sources

It is becoming increasingly important for companies to identify which external data sources may impact the behavior of their market, in order to obtain more accurate projections. It is key to verify that your source of information is stable and reliable before integrating it into the demand forecasting process.

If your industry requires it, you can carry out market research such as surveys, interviews or analysis of secondary data related to your products or services to obtain information about market or consumer preferences and behaviors.

The more variables and data sources you want to integrate, the more robust your information processing method needs to be — machine learning and deep learning models, for instance — in order to obtain valuable insights from complex data and a more reliable demand projection.

Keep in mind that the quality of the results you obtain will depend on the quality of your data and your sources.

2. Identifying variables

Defining the variables relevant to your company will help you establish mechanisms that improve accuracy when forecasting demand for products or services.

  • Price: Are you clear on whether price changes affect the quantity of products demanded? How volatile is the price behavior of your raw materials, and how does it affect the price of your products?
  • Income: Have you evaluated whether there is a relationship between consumer income and demand for your products?
  • Tastes and preferences: Is your demand sensitive to changes in consumer preferences? How can you get this information?
  • External factors: Do external variables such as the economy, politics, demographics and market trends affect the behavior of your demand? What are the most representative variables in your industry?

What other variable can affect the demand for your products or services and is considered representative in your industry?

3. Select the demand forecasting model

There are multiple demand forecasting methods, and selecting the right model is essential for companies that want to achieve better results.

Have you noticed that the same product can behave differently depending on how you analyze it? If you look at the behavior of the same product across different locations, channels or combinations, each of these may behave differently.

Some will be more stable and others more variable, which is why we recommend not relying on a single demand forecasting model for your products or services.

Causal methods

Causal methods are techniques used by companies to project demand for products or services by identifying and analyzing the causes that influence that demand.

  • Linear regression models: based on statistical techniques to identify relationships between variables.
y = α + βx

For example, imagine you are going to predict demand for ice cream (y) based on temperature (x). Assuming you have collected data and want to calculate the linear regression:

  • y = The dependent variable you want to predict: how many ice creams will I sell?
  • x = The independent variable, in this case temperature.
  • α = Intercept, which represents the value of sales when temperature equals zero.
  • β = Slope, which indicates how much ice cream sales change for each unit change in temperature.
y (Quantity of ice cream to sell) = α (50) + β (2) × x (Temperature)

This means that, according to the model, for each additional degree of temperature, ice cream sales are expected to increase by 2 units.

  • Multiple regression models: involve multiple independent variables. Multiple regression is useful when you need to predict a dependent variable (such as ice cream sales) based on two or more independent variables (such as price, advertising and temperature). The multiple regression equation can be expressed as follows:
y = α + β₁x₁ + β₂x₂ + β₃x₃

Based on the previous example, demand for ice cream (y) will be predicted from price (x₁), advertising (x₂) and temperature (x₃).

y = α + β₁ (Price) + β₂ (Advertising) + β₃ (Temperature)
y (Ice cream demand) = α (1,000) − (50 × Price) + (20 × Advertising) + (2 × Temperature)

This means that, based on our model, sales are expected to decrease by 50 units for each increase in price, increase by 20 units for each additional unit of investment in advertising, and increase by 2 units for each additional degree of temperature.

Time series

A time series is a set of data representing observations collected sequentially, usually at uniform intervals.

  • Simple moving average: a statistical method used to analyze time-based data and smooth out short-term fluctuations in order to identify long-term trends or patterns. Projecting demand with a simple moving average requires calculating the average demand for a product across successive time intervals, with the following equation:
y = ( Σ Demandᵢ ) ÷ n

Where:

  • y = Ice cream demand projection; the estimate of demand for the next period.
  • n = Number of periods included in the moving average.
  • Demandᵢ = Sales in period i.

For the monthly ice cream demand projection, a simple 3-month average will be used.

y = ( Salest−3 + Salest−2 + Salest−1 ) ÷ 3
y = ( January demand + February demand + March demand ) ÷ 3
y = ( 50 + 30 + 60 ) ÷ 3 = 46.6 ↦ average of 47 ice creams/month

The simple moving average is useful for smoothing seasonal fluctuations and highlighting medium-term trends in product demand or sales. Adjust the value of n depending on the quality of the data and the frequency of the fluctuations you want to smooth out.

  • Exponential smoothing: similar to the moving average, but weights are assigned to historical data to give greater relevance to the most recent information.
Ft+1 = α Yt + (1 − α) Ft
  • Ft+1: Estimated demand for the next period.
  • Yt: Demand in the current period.
  • Ft: Demand estimate for the current period.
  • α: Exponential smoothing factor. It determines how quickly the model reacts to new observations, with a value between 0 and 1.

When α is close to 1, more weight is given to the most recent data, causing the model to react quickly to changes in demand. When α is close to 0, the model tends to be more stable and less sensitive to recent variations. Here is an example:

If Yt = 100 ice creams and Ft = 90 ice creams for the current month, and α = 0.2 is defined to give more weight to recent values, the calculation would be:

Ft+1 = 0.2 × 100 + (1 − 0.2) × 90 = 20 + 72 = 92 ice creams projected for the next period.
  • Time series decomposition: used to break down a time series into its fundamental components — trend, seasonality and error — in order to obtain more accurate projections.
Yt = Tt + St + Et
  • Yt: Demand in period t.
  • Tt: The direction of demand over time (ascending, decreasing, constant).
  • St: Repetitive short-term patterns.
  • Et: Variation between trend and seasonality.

The following case serves as an example of forecasting demand with time series decomposition:

  • Yt = 100 ice creams for time t.
  • Tt = 90 ice creams as a long-term trend.
  • St = 20 ice creams equivalent to a seasonal pattern.
Et = Yt − Tt − St = 100 − 90 − 20 = −10 ice creams of residual error.
  • Collaborative forecasting: seeks collaboration between different stakeholders — internal areas, business partners, suppliers or even strategic customers — to generate more accurate forecasts based on different sources of information. Internally, it allows you to align the vision of various strategic areas within the supply chain, such as sales, marketing, operations and finance, including information such as negotiations, supplier constraints and marketing campaigns.

👨‍🏫 Learn more about collaboration in demand planning: S&OE vs S&OP

Let's look at an example that gives us the following data:

  • Marketing suggests that upcoming promotions may increase demand by 10%.
  • Sales provides information on market trends and expects an increase of 5% due to the Christmas season.
  • Production identifies constraints in the supply chain that could negatively affect sales, estimating a 3% reduction.
Collaborative forecast = Base forecast + Marketing input + Sales input + Operations input
= 1,000 + (1,000 × 0.10) + (1,000 × 0.05) − (1,000 × 0.03) = 1,120 ice creams

With business partners or strategic customers, it lets you include sell-out, negotiations and participation in marketing campaigns, among others.

With suppliers, it lets you give them advance notice or account for constraints they may have in meeting service levels.

This approach lets you take into account, for example, negotiations under way with customers, marketing campaigns, and other factors that may affect operations and service levels.

Artificial intelligence models

If you need to analyze large volumes of information and include complex variables, the right move is to use artificial intelligence models, because of the speed and precision with which they can process large volumes of data to project likely demand scenarios.

There are several artificial intelligence methods for processing demand forecasts, which may include supervised and unsupervised learning: machine learning, neural networks, deep learning and generative artificial intelligence. They give companies access to new levels of advanced analytics, such as predictive, prescriptive or cognitive models.

Some of the most used are machine learning models, which go through supervised learning so that, from historical data, they can learn patterns and produce accurate forecasts of future demand.

4. Establishment of scenarios

Establishing scenarios is a fundamental step in the process of forecasting demand for products or services. By analyzing different hypothetical situations or potential changes, companies can anticipate and be prepared for various situations that could affect demand.

  • Price scenarios: analyze how different price levels affect demand.
  • Economic scenarios: consider diverse economic situations and their impact on demand.
  • Price elasticity of demand: measures the sensitivity of demand to changes in price.
  • Promotions and events scenario: evaluate the impact of promotions, discounts or other marketing events on demand to optimize business strategies.
  • Seasonality scenario: consider seasonal patterns to anticipate predictable increases or decreases in demand, such as during holiday seasons or specific events.
  • Trend change scenario: analyze and project changes in demand trends, whether due to external factors, changes in consumer preference or innovations in the market.
  • New product introduction scenario: project demand when launching new products, considering consumer acceptance and competition.
  • Supply shortage scenario: anticipate demand shifts caused by potential supply chain disruptions and take preventive measures.
  • Government policy change scenario: evaluate how changes in government policies, such as trade or tax regulations, may affect demand.

Demand forecasting formulas: which one to use in each case

Three terms get used interchangeably in practice and they are not the same thing. Worth separating them before picking a formula:

  • The demand function is the relationship between price and the quantity the market is willing to buy. It is written as Q = a − bP.
  • The demand equation is that same relationship with your business numbers already in it: if a = 1,200 and b = 15, your equation is Q = 1,200 − 15P.
  • The supply and demand model is the point where both curves meet (Qd = Qs). That is the market clearing price: the level where you neither sit on inventory nor leave orders unserved.
Q = a − bP
Q = quantity demanded · P = price · a = demand at zero price · b = price sensitivity

If you sell at USD 80 with a = 1,200 and b = 15, your projected demand is Q = 1,200 − (15 × 80) = 0 units. Drop to USD 60 and it becomes 1,200 − 900 = 300 units. That is the exercise that tells you how far you can move price before demand collapses.

Price is rarely the only variable, though. This table helps you pick the method that matches the data you actually have:

Method Formula When to use it Data you need
Demand function (equation) Q = a − bP Price is what moves your sales most Price and unit sales history
Supply and demand equilibrium Qd = Qs You want the price at which the market clears Demand equation and supply equation
Linear regression y = α + βx A single external variable explains demand Sales history + that variable
Multiple regression y = α + β1x1 + β2x2 + β3x3 Several variables act at once Sales history + 2 or more variables
Simple moving average y = ( Σ Demandi ) ÷ n Stable demand, no marked trend n periods of history
Exponential smoothing Ft+1 = αYt + (1 − α)Ft You want recent data to weigh more Current demand + current forecast
Time series decomposition Yt = Tt + St + Et There is clear seasonality Two or more full cycles of history
Collaborative forecasting Base + input per area There are known promotions, campaigns or constraints Base forecast + sales, marketing and operations input

Market demand, projected demand and actual demand are not the same number

This is where teams get it wrong most often. One figure gets calculated, everyone calls it "demand", and it ends up driving three different decisions that need three different numbers.