Simple Demand Forecast Calculator
Turn a small history of demand values into a simple next-period forecast that you can use for ordering and planning.
Enter recent demand values separated by commas, spaces, or line breaks.
These tools are provided for educational and operational guidance only. Results are estimates and may not reflect all factors in your business. Always review calculations and use your own professional judgement before making decisions.
What is this tool?
This tool converts a short history of past demand into a single next-period forecast using a simple average. It is designed for quick planning discussions, not for complex statistical forecasting.
Formula
The calculator uses a straightforward formula:
Forecast = average of past demand values
If you input the last 4 weeks of demand, the forecast is simply the average of those 4 numbers. You can choose to include more or fewer periods depending on how stable your demand is.
Example
With past demand values 120, 130, 110, 140 units:
Forecast = (120 + 130 + 110 + 140) ÷ 4 = 125 units.
You can then use 125 units as the next-period forecast in your EOQ, safety stock, or reorder-point calculations.
When should you use this tool?
- When you need a quick forecast for ordering decisions and do not have complex systems.
- When demand is relatively stable and not strongly seasonal.
- When validating gut-feel estimates with a simple average of recent data.
- When communicating expected demand to suppliers or internal teams.
How this tool helps your business
- Reduces pure guesswork in planning by grounding decisions in recent history.
- Provides a simple, explainable forecast number for cross-team discussions.
- Helps you quickly test the impact of different demand assumptions on inventory plans.
- Encourages teams to collect and use basic demand data systematically.
Related tools
- EOQ Calculator – use the forecast as your demand input for order-size optimisation.
- Safety Stock Calculator – combine average demand with variability to set buffers.
- Reorder Point Calculator – convert the forecast into a reorder trigger together with lead time.
Frequently Asked Questions
How many periods of history should I include?
Use enough periods to capture a typical pattern without mixing very old behaviour—often 3–12 recent periods, depending on volatility and planning horizon.
Does this method handle trends or seasonality?
No, it assumes demand is roughly stable. For strong trend or seasonality you should adjust the average manually or use more advanced forecasting methods.
Should I clean unusual spikes from the history?
It is often helpful to exclude one-off events (for example large project orders) if they are not expected to repeat in the next period you are forecasting.
Can I use this forecast across multiple SKUs?
The simple average works per item or family. For groups of SKUs you may want to forecast at a higher aggregation level and then allocate down based on recent shares.