Demand Planning Crash Course
Interview prep sample · Demand planning analyst, consumer electronics

Demand Planning Crash Course

Everything in a demand planning job description, explained from zero for someone new to supply chain. Read it top to bottom on day one, practise on day two, skim the cheat sheet on the morning of the interview.

Next weekYour forecast window: 24 weekly buckets. Dark = near term, mostly fixed by supply lead time24 weeks out
The jobWeekly forecast and inventory analystBetween the sales teams and the supply chain
The core toolPSI table + ExcelPurchases, sales and inventory by account, product and week
Your edgeYour real backgroundThe data, operations or customer work you have actually done

One rule for every answer: talk only about experience you really have. Where you have none, say so plainly and show what you've learned and practised. All numbers on this page are illustrative, not real company data.

If you remember one thing

The job is a six-step weekly loop

Every responsibility in the JD is one of these steps. If you can explain them in your own words, you understand the role.

  1. Check the numbers (PSI)

    Pull the week's sales, purchases and stock for every account and product. Spot what moved.

  2. Clean and shape demand

    Fix data errors, tag one-off promotions, adjust for known events, all before the weekly deadline.

  3. Agree and load the forecast

    Agree the numbers with the sales and account teams, add the safety buffer, and load the forecast into the planning system.

  4. Publish the weekly report

    What changed since last week, what's at risk, and what it means in dollars against the sales plan.

  5. Match supply to the plan

    Check factory arrival dates, reconcile channel inventory, and confirm or adjust purchase orders.

  6. Stop stock from getting old

    Find aging stock, plan how to sell it down, and move it to where it sells faster.

The business in one picture

Follow one phone from factory to customer

The factory has to decide how many to build weeks before anyone buys. Too few means empty shelves and lost sales. Too many means phones losing value in a warehouse. Demand planning exists to get that number right.

FactoryThe brand's factory (for phones, often in Asia) builds it; ship takes weeks, air takes days
Sales subsidiaryThe brand's company in each country, with its warehouses
AccountWireless carriers, big-box retailers, online marketplaces
ConsumerBuys in a store or online
Factory → subsidiary: arrivals, POsSubsidiary → account: sell-inAccount → consumer: sell-throughStock left at the account: channel inventory
WhoWhat they areSoftware comparison
Sales subsidiaryThe brand's company in one country. Buys from HQ, sells to accountsA regional deployment
Planning / business operationsTurns sales input into numbers the supply chain can act on. This is the team you'd joinThe integration layer between two systems
CarriersWireless carriers. Sell phones with service plans; promotions cause sudden spikesA client with bursty traffic
RetailersElectronics chains, hypermarkets, warehouse clubs and online marketplaces. Many brands; seasonal peaks (back-to-school, holidays)A client with predictable seasonal load
Account teamsThe brand's people who own each customer relationship. Your main counterparts every weekClient-facing account managers
Tap each one open

The 18 concepts, from zero

Each card has the plain-English meaning, an everyday example, the numbers, a software comparison, and how interviewers ask about it with a one-line answer you can adapt.

Change the numbers, watch what happens

Practice calculators

These are the three calculations most likely to come up. Change any input. The sentence under each tool is how you'd say the result in the interview.

1 · PSI table and weeks of supply

WeekOpeningPurchases (sell-in)Sales (sell-through)Ending (EOH)WOS

2 · Forecast accuracy: MAPE vs WAPE vs bias

ModelForecastActualError F − A% error
MAPE (each model equal)–
WAPE (weighted by volume)–
Accuracy = 1 − WAPE–
Bias (+ = too high)–

3 · Reallocating company-held stock between two locations

X weeks to deplete–
Y weeks to deplete–

Tap the card to flip it

Flashcards

Say the answer out loud before you flip. Shuffle and go again until none of them surprise you.

Twelve questions, instant feedback

Self-check quiz

Work the maths on paper first, then tap your answer.

Map your real background to the job

Your story

Every answer comes from what you've actually done, studied or built. Use this table to connect your background to what the team needs.

What the JD wantsAsk yourselfHow to use it
Find trends, variances, risksWhen did you trace a wrong number back to its source?A short STAR story: what was wrong, how you found it, what changed
Advanced ExcelWhich Excel tools can you use live, without help?Claim only those, and practise the rest before the interview
Reports and dashboardsWhat report or dashboard have you built, and who used it?A real STAR story with what you built and who used it
Presenting to senior peopleWhen did you explain numbers or progress to managers or clients?Use the headline → drivers → risks → decision structure
Multi-cultural teamsHave you worked across countries or time zones?A real STAR story
Demand planning job experienceIf you have none yet, say soThen show what you've learned and practised. Interviewers trust this more than a vague claim

60–90 second pitch (a template)

  1. Your background in one sentence, and where you worked with data or operations.
  2. Why planning: a real reason connected to your experience.
  3. What you've done to learn it: courses, projects and practice you've actually completed.
  4. What you'd bring to this team's weekly cycle.

Real experience only. If you're asked about something you haven't done, say so plainly and explain how you'd approach it. Invented details fall apart under the second follow-up question, and employment history gets checked.

Tap a question to see what a strong answer covers

Likely interview questions

These are frameworks, not scripts. Put them in your own words and practise out loud. Behavioural answers must use your real experience.

Ticks are saved in this browser only

Your 2-day plan

Interview morning, 10 minutes

Cheat sheet

PSI identityEOH = Opening + Purchases − Sales
Channel inventory changeSell-in − Sell-through
Weeks of supplyWOS = EOH ÷ forward weekly sales
Forecast to loadConsensus × (1 + buffer %)
AccuracyWAPE = Σ|F − A| ÷ ΣA · Acc = 1 − WAPE
Direction of errorBias = Σ(F − A) ÷ ΣA
Every model equalMAPE = average of |F − A| ÷ A
Money$ impact = units × ASP
AgingWeeks to deplete = stock ÷ weekly sales
Supply checkGap = requirement − confirmed arrivals (+ = short)

Five questions to ask them

  1. How many forecast versions does the team run each week, and who owns each one?
  2. Which accounts or product lines would I support first?
  3. How does the team measure forecast accuracy and bias today?
  4. Which systems and data sources does the team use day to day?
  5. What does a great first 90 days look like in this role?
Watch, listen, practise

Resources

The videos and articles below cover every concept on this page. In a full prep pack they also go into a NotebookLM notebook, with AI-generated audio and video overviews.

AI-generated audio and videoPart of a full prep pack: a NotebookLM notebook built from these sources, with a podcast-style overview, a video explainer, a quiz and flashcards.
Excel practice workbook"demand-planning-excel-practice-workbook.xlsx": six exercises (lookups, PSI, accuracy, WoW report + pivot, aging, reconciliation + PO) with answer keys
Podcasts and videos (files)Beginner deep-dive podcast, a second deep-dive podcast, a beginner whiteboard video, an analyst playbook video, slides (PDF/PPTX), study guides, question bank

Watch first (in this order)

More videos and reading