Free forecast calculator
Paste a column of numbers — monthly sales, weekly signups, daily visitors — and get an auto-tuned trend forecast with a chart, a confidence range and a downloadable CSV. Runs entirely in your browser; your data never leaves your device.
How it works
No black box — here's exactly what the calculator does.
It parses your numbers in the order you paste them, treating them as evenly spaced time periods.
It uses Holt's linear exponential smoothing and searches for the smoothing weights that minimise one-step forecast error on your own data.
It carries the fitted level and trend forward for the number of periods you choose, and adds an ~80% confidence range that widens with distance.
It's a trend forecast, not a crystal ball. For strong seasonality (e.g. December spikes every year), use a seasonal method — that's where the full DataHub Pro platform helps.
FAQ
How does this forecast calculator work?
It uses Holt's linear exponential smoothing — a standard time-series method that tracks the level and trend of your series. The calculator auto-tunes its smoothing parameters by minimising one-step forecast error on your own data, then projects the trend forward for the number of periods you choose.
Is the forecast calculator free?
Yes, completely free with no sign-up. It runs entirely in your browser, so your numbers never leave your device. You can also embed it on your own site for free.
What data do I need to make a forecast?
A single column of numbers in time order — for example monthly sales, weekly signups or daily visitors. Around 8 or more points gives a more reliable trend. Paste them one per line or comma-separated.
Need seasonality, multiple series and reports?
DataHub Pro forecasts seasonal data, builds the dashboard and writes the report — from your spreadsheet, in minutes.
Try DataHub Pro free →