Try It Live
Choose a metric (Sales Revenue, Labour Costs, Staffing Headcount, or your own), load the pre-filled sample data or enter your own, add any upcoming events or campaigns, and hit Generate Forecast. The dashboard renders a line chart showing historical actuals alongside a projected trend, a confidence band, an AI insight summary, and a period-by-period breakdown table.
How It Works
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Choose your metric — Sales Revenue, Labour Costs, Operating Costs, Staffing Headcount, Customer Volume, or any custom metric with a free-text label and unit.
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Enter historical data — Use the editable table pre-loaded with 12 months of sample retail data, or upload your own two-column CSV (Period, Value). Any frequency works: weekly, monthly, or quarterly.
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Add context — Specify upcoming campaigns, trade shows, product launches, or other events with an expected impact level. The AI weighs these against the statistical baseline.
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Forecast generates in two steps:
- A statistical baseline is computed server-side using linear regression on the historical data, with a 90% confidence band derived from the model's residual error.
- GPT-4o-mini then applies per-period adjustment multipliers based on your events, built-in US holiday calendar, and any seasonality visible in the historical pattern. The AI explains every adjustment.
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Dashboard renders — A static SVG line chart shows historical actuals (solid line) and the adjusted forecast (dashed line) with confidence band. Below it: an AI insight paragraph, a key-factors summary, and a scrollable period table showing baseline vs. adjusted values and the AI's reasoning for each period.
What This Demonstrates
| Capability | Description |
|---|---|
| Hybrid forecasting | Statistical baseline + AI qualitative adjustment — more reliable than pure LLM number generation |
| Structured AI output | GPT-4o-mini returns JSON with per-period multipliers, reasoning, and narrative |
| Event-aware forecasting | Named events with impact levels shift the forecast for affected periods |
| Holiday calendar | US holidays automatically factored into the AI's adjustment logic |
| Flexible data input | Manual table or CSV upload; weekly, monthly, or quarterly data |
| Static SVG dashboard | Rendered server-computed data — no charting library dependency |
| Explainability | Every forecast adjustment includes a plain-English reason |
Use Cases
- Monthly and quarterly revenue forecasting for sales leadership
- Labor cost and headcount planning for HR and finance teams
- Demand forecasting for inventory management and supply chain optimization
- Capital expenditure planning and cash flow projection for CFOs
- Customer volume projections for capacity planning and staffing
- Marketing campaign ROI forecasting and budget allocation
From Demo to Production
This demo shows how a hybrid statistical + AI model can produce an explainable, event-aware forecast from a single data series. A production deployment takes it further by connecting to live data sources, running multiple forecast models in parallel, and delivering results to the tools your team already uses.
Real-World Challenges
| Challenge | Why It's Hard | How to Solve It |
|---|---|---|
| Data quality and missing periods | Historical data often has gaps, outliers, or regime changes (COVID, M&A, product launches) that distort the baseline | Implement automated data cleaning, outlier detection, and regime-change markers that the model can account for |
| Forecast accuracy expectations | Leadership expects precise numbers; models produce probability ranges — the gap creates trust issues | Educate stakeholders on confidence intervals; track and publish accuracy metrics (MAPE, bias) over time to build credibility |
| Conflicting departmental forecasts | Sales, finance, and operations each produce their own forecast using different assumptions | Establish a single forecasting engine as the baseline; layer departmental adjustments transparently on top |
| Incorporating qualitative intelligence | Sales rep gut feel, market rumors, and competitive moves don't fit neatly into a statistical model | Provide structured input fields for qualitative events (like this demo does) and weight them against the statistical baseline |
| Model drift and retraining cadence | Forecast accuracy degrades as market conditions change; models need regular recalibration | Automate accuracy monitoring and trigger retraining when MAPE exceeds a threshold; retrain monthly at minimum |
Cost Estimates
| Line Item | Small (Single Team) | Mid-Market (Finance Dept) | Enterprise (Multi-BU) |
|---|---|---|---|
| AI API + statistical compute | $30–100/mo | $100–400/mo | $400–1,500/mo |
| Data warehouse / ERP integration | $50–200/mo | $200–800/mo | $800–3,000/mo |
| Model maintenance (labor) | $100–200/mo | $200–500/mo | $500–1,500/mo |
| Hosting & infrastructure | $0–20/mo | $20–100/mo | $100–500/mo |
| Total monthly | $100–400 | $400–1,500 | $1,500–5,500 |
ROI Definition
- Primary metric: Forecast accuracy improvement — target MAPE (Mean Absolute Percentage Error) reduction of 15–30% vs. existing process
- Secondary metrics: Time saved on forecast preparation, reduction in over/understock costs, improved cash flow predictability
- Break-even timeline: 1–3 months depending on scale and current forecast maturity
- Example: A retailer with $20M annual revenue improving forecast accuracy by 20% reduces overstock and understock costs by 3–5% of revenue = $600K–$1M/year saved vs. ~$15K/year in tool costs.
Build It or Buy It?
The statistics are free — and the model should not be writing the numbers — priced comparison of the three routes
Before any pricing, the design point that matters most: a language model should not be producing the forecast. Numeric extrapolation is not what these models are good at, and a plausible-sounding number carries no confidence interval and no auditable method. The statistical model produces the figure; the language model explains it, adjusts for events you describe, and writes the narrative. That is what this demo does, and it is the right division of labour.
With that settled, here are the three routes for a mid-sized workload — 500 series, forecast weekly across a 52-week horizon, refreshed monthly — which is 26,000 forecast data points a month.
| Route | What you pay | Per month |
|---|---|---|
| Build on open-source statistics — Prophet, statsmodels, ARIMA | No licence at all. Compute only; 500 series takes minutes on a small instance | ~$0 licence |
| Buy a forecasting API — Amazon Forecast | $2.00 per 1,000 forecast data points for the first 100K/month, declining to $0.02 per 1,000 above 50M. Plus $0.24/hour predictor training and $0.088/GB data import | ~$52 plus training |
| Buy a planning platform — Anaplan, Pigment, Workday Adaptive Planning | Not published | quote-only — see the sourcing note |
The forecasting mathematics has been free and open source for years. Prophet, ARIMA, exponential smoothing and the rest are mature, well-documented, and carry no licence cost. That is genuinely unusual — in most of these demos the build route trades money for engineering, but here the core capability is a free library and a moderate amount of statistical literacy.
So what does $52/month actually buy? Managed training, automated model selection across several algorithms, and not having to own the statistics yourself. That is a reasonable trade if nobody on the team wants to reason about seasonality and stationarity. It is a poor trade if someone does, because the same result is a free library away.
Note the tier structure. Amazon Forecast's first 100,000 data points a month are the most expensive ones at $2.00 per 1,000, falling a hundredfold to $0.02 above 50M. Small deployments pay the worst rate — which is the opposite of the usual assumption that managed services get cheaper at small scale.
The planning platforms are a different purchase entirely. They are not forecasting engines; they are the place where finance argues about the number, holds scenarios side by side and locks a version. None publishes list pricing, so no figure is quoted here.
What building it actually requires — skills, systems and the ongoing work
Skills you need on hand
| Area | Why it is needed |
|---|---|
| Applied time-series literacy | Not a research background, but someone who understands seasonality, trend, stationarity and why a confidence interval matters more than the point estimate. Without this, the library will happily produce something confident and wrong. |
| Backtesting discipline | Holding out recent periods and measuring error honestly. A forecast that has never been scored against what actually happened is a decoration. |
| Event and calendar data | Promotions, price changes, holidays, closures, campaigns. This is the input that separates a useful forecast from a trend line, and it usually does not exist in structured form yet. |
| Hierarchy reconciliation | Forecasts by SKU must sum to the category, and the category to the total. They will not do so by default, and finance will notice immediately. |
| Data plumbing | Clean, gap-free history at a consistent grain. Every real dataset has missing weeks, unit changes and a system migration in the middle. |
The part that is easy to underestimate: your accuracy ceiling is set by what you recorded, not by which model you pick. If promotions were never logged, no algorithm can attribute the spike or predict the next one. Teams routinely try three modelling approaches when the actual constraint is that nobody wrote down when the discount ran.
The specific trap worth naming: a stockout looks exactly like low demand. If you forecast from sales rather than demand, every period where you ran out teaches the model to expect less, so you order less, and run out again. This is censored demand, it is self-reinforcing, and it is invisible unless someone deliberately corrects for it.
Choose build when you have clean history, someone comfortable with the statistics, and the forecast feeds your own systems. The libraries are free and very good.
Choose a forecasting API when you want managed training and model selection and would rather not own the mathematics.
Choose a planning platform when the hard part is not producing the number but agreeing on it — multiple contributors, versioned scenarios, an audit trail, and a board pack at the end.
What to expect if you go ahead — timeline, accuracy, and where it goes wrong
Timeline. A working forecast on clean data takes days. Getting the data clean, the events recorded and the hierarchy reconciling takes weeks to months, and that is the project.
Accuracy, stated honestly. Expect meaningful improvement over a naive baseline on series with real seasonality and enough history. Expect very little on short, sparse or intermittent series — new products, long-tail SKUs, anything with mostly zeros. Those are exactly the items people most want forecast, and they are the ones where statistical methods have least to offer.
Always measure against the naive baseline. Last period repeated, or last year's same period. A surprising number of forecasting projects never beat it, and without that comparison nobody finds out. If your model cannot beat "same as last year", it is not ready and no amount of tuning at the model layer will fix it.
Report the interval, not just the point. A forecast of 1,000 units is not actionable. A forecast of 1,000 with an 80% interval of 850–1,150 is, because it tells you what to hold. Systems that surface only the point estimate quietly encourage people to treat an estimate as a commitment.
Where it actually goes wrong
- Censored demand — forecasting from sales rather than demand, so stockouts train the model downward in a self-reinforcing loop.
- A one-off event is learned as seasonality. A single unusual month is absorbed as a recurring annual pattern and reappears in the forecast forever.
- Hierarchies that do not reconcile, so the sum of the parts contradicts the total and finance stops trusting all of it.
- A pipeline change silently alters the grain — daily becomes weekly, or a unit definition shifts — and accuracy degrades with nothing erroring.
- The forecast is never scored. No backtest, no error tracking, so nobody can say whether it works, and it drifts from useful to decorative without a moment where anyone notices.
The honest question to ask first: can you beat "same as last period" today, and do you know by how much? If you cannot answer that, start by measuring your current process against a naive baseline. It costs nothing, it takes an afternoon, and it will tell you whether you have a forecasting problem or a data-recording problem — which are solved very differently.
Sourcing note. Prices above are list prices read from vendor documentation in August 2026: Amazon Forecast. Amazon Forecast also offers a free tier of up to 100,000 forecast data points per month for new customers during their first two months. Prophet, statsmodels and ARIMA implementations are open source and carry no licence cost; the "~$0" figure is licence cost only and excludes the compute to run them. Anaplan, Pigment and Workday Adaptive Planning do not publish list pricing and are deliberately absent rather than estimated — expect enterprise planning platforms to be a materially larger number than anything in the table above, and get a quote. Verify current pricing before committing.
Technology Stack
- AI Model: OpenAI GPT-4o-mini
- Statistics: Linear regression with RMSE-based confidence intervals (computed server-side in TypeScript, no external library)
- Frontend: React client component — multi-step form, editable data table, CSV upload, static SVG chart
- Backend: Next.js API route (serverless)
- Chart: Hand-built SVG (historical line + forecast line + confidence band + event markers)
Want This for Your Business?
A production deployment connects directly to your source systems — POS, ERP (SAP, NetSuite), HRIS (ADP, Workday), or data warehouse — and runs forecasts on a schedule. Results are pushed to dashboards in Power BI, Looker, or Tableau, or delivered as weekly email summaries to managers. The model retrains continuously as new actuals come in. A full deployment typically takes 2–3 weeks and starts at $3,500.