# Demand Planning

Demand planning is the process of estimating future customer demand and translating those estimates into actionable plans that drive supply, inventory, and financial decisions across the business. 🎯

It sits at the heart of every IBP process — get demand wrong, and everything downstream suffers.


# Demand Planning vs. Demand Forecasting

These terms get used interchangeably, but they shouldn't be.

Demand Forecasting Demand Planning
Scope Generating a numerical estimate of future demand End-to-end process: forecast, consensus, shaping, communication
Inputs Historical data, statistical models Forecasts + market intelligence + business strategy
Output A baseline forecast An agreed demand plan aligned with business objectives
Who owns it Analytics / data science Demand planning team with cross-functional input

Forecasting is a component of demand planning — an important one, but not the whole story. A demand plan also incorporates demand shaping decisions, new product launches, and consensus from sales and marketing.


# The Demand Planning Process

At a high level, the demand planning cycle follows four steps:

  1. Data cleansing — Remove outliers, correct errors, handle promotions and one-off events so history reflects true underlying demand.
  2. Statistical baseline — Apply forecasting models to generate an unbiased starting point (see methods below).
  3. Enrichment — Layer in market intelligence, sales input, promotional plans, and known events.
  4. Consensus — Cross-functional review to agree on one demand number the organization will execute against.

This cycle typically repeats monthly in an IBP cadence, though short-term adjustments may happen weekly via demand sensing.


# Statistical Forecasting Methods

Averages the last n periods of demand. Simple and transparent, but lags behind trends and ignores seasonality. Best suited for stable, mature products with low variability.

\displaystyle F_t = \frac{1}{n} \sum_{i=1}^{n} D_{t-i}

Applies exponentially decreasing weights to older observations. More responsive than moving average, with a smoothing parameter alpha controlling how fast old data is discounted. Variants (Holt, Holt-Winters) handle trend and seasonality.

\displaystyle F_t = \alpha \cdot D_{t-1} + (1 - \alpha) \cdot F_{t-1}

Models demand as a function of one or more independent variables (price, GDP, weather, marketing spend). Useful when causal drivers are well understood, but requires clean driver data and careful variable selection.

\displaystyle D = \beta_0 + \beta_1 X_1 + \beta_2 X_2 + \cdots + \epsilon

# Judgmental Forecasting

Statistical models can't capture everything. Judgmental forecasting fills the gap:

  • Sales input — Account-level intelligence on pipeline, customer plans, and competitive dynamics.
  • Market intelligence — Category trends, regulatory changes, macroeconomic shifts.
  • Event-driven adjustments — Promotions, product launches, supply disruptions, weather events.

The key is to apply judgment on top of a statistical baseline, not instead of one. Unstructured overrides tend to introduce bias rather than accuracy — this is why tracking Forecast Value Added matters.


# Override Governance

To keep overrides useful, define clear rules for when and how they are allowed.

Override Type Trigger Threshold Required Approval Documentation Required
Minor adjustment Within +/- 10% vs statistical baseline Demand planner Reason code and supporting note
Material adjustment Above +/- 10% to +/- 20% Demand manager + sales lead Customer/market evidence and impact summary
Major adjustment Above +/- 20% Demand manager + commercial VP + finance partner Formal assumption pack, risk statement, and mitigation actions

Operating rules:

  • Start from the statistical baseline every cycle.
  • Require explicit reason codes for every override.
  • Use FVA monthly to confirm overrides improve outcomes.
  • Retire override patterns that repeatedly reduce accuracy.

# Exception Review Format

Demand reviews should focus on exceptions, not every SKU. Use a consistent format to keep the discussion decision-oriented.

Field What to Capture
Item / Family Where the exception exists
Exception Type Volume miss, mix shift, event risk, launch risk
Magnitude Unit and percentage impact vs baseline
Root Cause What changed and why
Recommended Action Proposed adjustment or mitigation
Owner Accountable person for action
Due Date Date for closure or next checkpoint
Escalation Need Yes/No; if yes, route to supply/finance/MBR

Recommended working rule:

  • review top 10-15 exceptions by business impact each cycle
  • close or escalate each exception before meeting end

# Demand Segmentation: ABC-XYZ Analysis

Not all items deserve the same forecasting approach. ABC-XYZ analysis classifies products on two dimensions:

  • ABC (volume / revenue contribution): A = top 80%, B = next 15%, C = remaining 5%
  • XYZ (demand variability): X = low variability, Y = moderate, Z = highly erratic
X (Stable) Y (Variable) Z (Erratic)
A (High volume) Statistical forecast; high automation Statistical + judgmental overlay Judgmental; event-driven
B (Medium volume) Statistical forecast; periodic review Blend of statistical and judgmental Judgmental; safety stock focus
C (Low volume) Simple model or rule-based Rule-based; minimal effort Make-to-order or carry safety stock

This matrix helps demand planners allocate their time where it matters most — spend energy on high-value, hard-to-forecast items (AY, AZ) rather than spreading attention evenly.


# Planning Horizons 📆

Horizon Timeframe Primary Use Typical Granularity
Short-range 0–3 months Execution, replenishment, scheduling SKU-location, daily/weekly
Medium-range 3–18 months S&OP/IBP, capacity planning, budgeting Product family, monthly
Long-range 18–36+ months Strategic planning, network design, capital investment Category / business unit, quarterly

Short-range forecasts benefit most from demand sensing. Medium-range is the sweet spot for the IBP process. Long-range planning is less about precision and more about directional alignment with strategy.


# Further Reading