Chart Trendline Formulas

Category: Formulas / Charts & Graphics | [Item URL]

When you add a trendline to a chart, Excel provides an option to display the trendline equation in the chart. This tip describes how to create formulas that generate the trendline coefficients. You can then use these formulas to calculate predicted y values for give values of x.

These equations assume that your sheet has two named ranges: x and y.

Linear Trendline

Equation: y = m * x + b
m: =SLOPE(y,x)
b: =INTERCEPT(y,x)

Logarithmic Trendline

Equation: y = (c * LN(x)) + b
c: =INDEX(LINEST(y,LN(x)),1)
b: =INDEX(LINEST(y,LN(x)),1,2)

Power Trendline

Equation: y=c*x^b
c: =EXP(INDEX(LINEST(LN(y),LN(x),,),1,2))
b: =INDEX(LINEST(LN(y),LN(x),,),1)

Exponential Trendline

Equation: y = c *e ^(b * x)
c: =EXP(INDEX(LINEST(LN(y),x),1,2))
b: =INDEX(LINEST(LN(y),x),1)

2nd Order Polynomial Trendline

Equation: y = (c2 * x^2) + (c1 * x ^1) + b
c2: =INDEX(LINEST(y,x^{1,2}),1)
C1: =INDEX(LINEST(y,x^{1,2}),1,2)
b = =INDEX(LINEST(y,x^{1,2}),1,3)

3rd Order Polynomial Trendline

Equation: y = (c3 * x^3) + (c2 * x^2) + (c1 * x^1) + b
c3: =INDEX(LINEST(y,x^{1,2,3}),1)
c2: =INDEX(LINEST(y,x^{1,2,3}),1,2)
C1: =INDEX(LINEST(y,x^{1,2,3}),1,3)
b: =INDEX(LINEST(y,x^{1,2,3}),1,4)

Higher Order Polynomial Trendline

Notice the pattern in the two preceding sets of formulas.

Search for Tips

All Tips

Browse Tips by Category

Tip Books

Needs tips? Here are two books, with nothing but tips:

Contains more than 200 useful tips and tricks for Excel 2007 | Other Excel 2007 books | Amazon link: John Walkenbach's Favorite Excel 2007 Tips & Tricks

Contains more than 100 useful tips and tricks for Excel 2013 | Other Excel 2013 books | Amazon link: 101 Excel 2013 Tips, Tricks & Timesavers

© Copyright 2016, J-Walk & Associates, Inc.
Privacy Policy