Forecast a CSV or Excel time series
Upload a CSV or Excel file with dates and numbers and get a forecast, a chart and a likely range. It tests several methods and picks the best one. Free, and your file never leaves your browser.
When to use it
If you have a column of dates and a column of numbers, such as monthly sales, daily visits or weekly orders, you can forecast the next periods here without writing code.
The tool tries several simple methods, tests each on the most recent part of your data, and uses the one with the smallest error. It shows the forecast, a rough range and which method won. It is a quick first look, not a replacement for a full analysis.
How it works
- Drop in a CSV or Excel file, or press the sample button to see how it works.
- Check the date column and the number column it picked, and choose how far ahead to forecast.
- Read the chart and the table, then download the forecast as a CSV.
Questions
How does it make the forecast?
It tries several classic methods: repeat the last value, repeat the last season, a straight trend line, Holt trend smoothing and Holt-Winters with seasonality. It hides the last few points, checks which method predicts them best, and uses that one on your whole series.
What data does it need?
One column of dates and one column of numbers, at regular steps such as daily, weekly, monthly or quarterly. At least 6 points are needed, and seasonal methods need two full seasons, for example 24 months of monthly data.
How accurate is it?
It depends on how steady your data is. The shaded range shows where values are likely to land about 80 percent of the time, based on past errors. It cannot predict one-off events such as promotions or shocks, so treat it as a starting point.
Is my file uploaded anywhere?
No. Everything runs inside your browser tab and nothing is sent to a server.
Which date formats work?
Formats such as 2024-03-15, 15/03/2024, Mar 5 2024 and 2024-03 work. For dates like 03/04/2024 it reads the first number as the day.
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