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Statistical function

FORECAST.LINEAR

Predicts a y value for a given x using linear regression.

CommonDifficulty 1300 · ProficientUsage rank #125 of 520
Practice · 3 questions →

When to use it

Predicts a y value for a new x using the straight line through the known points. The successor to FORECAST.

The shape of it

Syntax
=FORECAST.LINEAR(x, known_ys, known_xs)

Worked examples

  • Next point

    =FORECAST.LINEAR(5,{2,4,6,9},{1,2,3,4}) → 11

    Intercept -0.5 plus slope 2.3 times 5.

  • Next month

    =FORECAST.LINEAR(13,B2:B13,A2:A13) → 38,200

    Month 13 from twelve months of data.

  • Forecast by date

    =FORECAST.LINEAR(DATE(2026,1,1),B2:B37,A2:A37) → 1,244

    Dates are numbers, so they work as x.

Worth knowing

  • For seasonal data use FORECAST.ETS instead.
  • TREND does the same for a whole array of new x values.
  • Chart the points with a trendline to see whether a line is even appropriate.

Where it goes wrong

  • #DIV/0! when x is constant.
  • Extrapolating far beyond the data assumes the trend continues, which it often does not.

Related

AVERAGECOUNTCOUNTACOUNTIFCOUNTIFSMAX

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