Online Tool Store
Simple Forecast Tool
Enter a series of past values to project future periods using a simple moving-average and linear-trend forecast, shown on a chart.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Example monthly revenue shown — replace it with your own series.
Trend / period
—
3-period moving avg
—
Next period forecast
—
How Simple Forecast Tool works
- Paste your past values, oldest to newest, comma-separated — a sample ten-month revenue series is pre-filled.
- The tool fits a least-squares linear trend line through the series, treating each value's position (1st, 2nd, 3rd…) as the x-axis.
- Choose how many future periods to project; the trend line extends forward by that many steps to produce the forecast.
- The chart shows your history as a solid line, the fitted trend as a thin dashed line across the whole range, and the forecasted periods as a blue dashed continuation.
The regression solves for slope and intercept in value = intercept + slope × period by minimizing the sum of squared errors between the line and your actual values — the standard definition of a best-fit line.
FAQ
What method does the forecast use?
Ordinary least-squares linear regression against period index — the same method behind a spreadsheet's TREND() or FORECAST.LINEAR() functions. It fits the straight line that minimizes the squared distance to every point in your series, then extends that line forward.
Why does the tool also show a moving average?
The 3-period moving average is a smoothed read of where the series currently sits, separate from its long-run direction — useful for sanity-checking the trend line against recent values, since a sharp recent swing can pull the two apart.
How much history do I need for a useful forecast?
The regression works with as few as two points, but a trend fit to 2-3 points is really just drawing a line through them — six or more periods gives the slope enough data to reflect a genuine pattern rather than noise.
How we compare
| Feature | Online Tool Store | Doing it manually | A generic online tool |
|---|---|---|---|
| No file upload — runs in your browser | ✓ | N/A | ✗ |
| No sign-up required | ✓ | ✓ | ✗ |
| Free, no watermark | ✓ | ✓ | ✗ |
Building a trend line in a spreadsheet means creating a chart, adding a trendline, and reading the equation off a tooltip. This tool does the regression directly and states the equation, next-period value, and moving average as plain numbers — paste a series and read the answer immediately.