Exponential Function in Excel: EXP, ^, GROWTH and LOGEST

Short answer: in Excel, =EXP(number) returns e raised to the power of number (e ≈ 2.71828182845904). For any other base use the ^ operator or POWER. To fit an exponential curve to data, use GROWTH or LOGEST. This guide is for researchers who need to compute, fit and interpret exponential values in a worksheet.

What the exponential function is used for in research

Exponential relationships appear wherever a quantity changes by a constant factor per unit of x: culture growth, decay, signal attenuation. In a worksheet you usually need one of two things: to compute a single value such as e^x (EXP), or to fit y = b·m^x to measured data (GROWTH, LOGEST). For the statistics behind the fit, see our guide to exponential regression.

Access: built-in functions

EXP, POWER, GROWTH, LOGEST and SUM are all built-in worksheet functions documented by Microsoft Support (links under Sources). No add-in is needed; type the formula into a cell beginning with an equals sign.

Step-by-step: how to use the exponent function (EXP)

1. Click an empty cell.
2. Type =EXP(2) and press Enter. Excel returns 7.3890561, which is e raised to the power of 2.
3. Replace the 2 with a cell reference (for example =EXP(B2)) and fill down to apply it to a column of exponents.
4. Check the result with =EXP(1), which returns 2.71828183, the approximate value of e.

What does “EXP” mean?

EXP is the exponential function with base e: it returns e raised to the power of the number you supply. Microsoft documents it as the inverse of LN, the natural logarithm, so =LN(EXP(2)) returns 2.

Exponent with other bases: ^ and POWER

EXP is only for base e. Microsoft’s EXP page directs you to the exponentiation operator (^) for other bases. The POWER function is equivalent: =5^2 and =POWER(5,2) both return 25. Microsoft’s POWER examples include =POWER(98.6,3.2) = 2401077.222 and =POWER(4,5/4) = 5.656854249, showing that fractional exponents work.

Which function to use

Task	Function	What it returns
e raised to a power	EXP(number)	enumber
Any base raised to a power	number^power or POWER(number,power)	numberpower
Predict y values from an exponential fit	GROWTH(known_y's,[known_x's],[new_x's],[const])	y-values on the fitted curve y = b·mx
Get the fitted curve’s coefficients	LOGEST(known_y's,[known_x's],[const],[stats])	An array {m, b} for y = b·mx

Fit an exponential model: GROWTH and LOGEST

Microsoft’s own GROWTH example uses month numbers 11 to 16 with unit counts 33,100; 47,300; 69,000; 102,000; 150,000; 220,000. With the months in A2:A7 and the units in B2:B7, =GROWTH(B2:B7,A2:A7) returns the fitted values 32,618; 47,729; 69,841; 102,197; 149,542; 218,822. Supplying new x-values predicts beyond the data: =GROWTH(B2:B7,A2:A7,A9:A10) for months 17 and 18 returns 320,197 and 468,536.

LOGEST fits the same model but returns the coefficients m and b in y = b·m^x. To pull out just b, Microsoft shows INDEX(LOGEST(y,x),2). In Microsoft 365 you enter these with a plain Enter; in older versions, array formulas need Ctrl+Shift+Enter. Setting const to FALSE forces b = 1.

What is the formula for an exponential equation?

The form Excel fits is y = b·m^x. Because m^x = e^{x·ln m}, the same curve can be written y = b·e^kx with k = LN(m). This conversion is a standard identity, not something Excel computes for you. In the GROWTH example above, consecutive fitted values rise by a factor of about 1.46 per month (47,729 / 32,618), giving k ≈ ln(1.463) ≈ 0.38 per month. Use =LN(m) on the m returned by LOGEST, and =EXP(k*x) to rebuild the curve.

Reading the output

• m is the multiplicative factor per one-unit increase in x; m > 1 means growth and m < 1 means decay.
• b is the fitted value at x = 0.
• k = LN(m) is the continuous rate if you prefer the e^kx form.
• Microsoft notes that extrapolating outside the range of your data may not be valid; treat the predictions for months 17 and 18 above as model output, not observations.

To draw the curve on a chart instead, see how to add a trendline in Excel. For other Excel statistics tasks see F-test in Excel and calibration graphs in Excel.

Troubleshooting

• #NUM! from GROWTH: Microsoft documents that zero or negative known_y’s produce #NUM!. Exponential fits need strictly positive y.
• Only one value appears: in versions before Microsoft 365, enter array functions with Ctrl+Shift+Enter.
• Wrong base: EXP(2) is e² = 7.389, not 2². For base 2 or 10 write =2^x or =10^x.

How to do ∑ (sum) in Excel

The ∑ sign corresponds to the SUM function. Its syntax is SUM(number1,[number2],...), and each argument can be a number, a cell reference such as B6, or a range such as B2:B8. For example, =SUM(A2:A10) adds the values in A2:A10. To sum exponentials, fill a helper column with =EXP(A2) and sum that column.

Free alternatives

Tool	ex	Other base
R	exp(x)	2^x
Python	math.exp(x)	2**x

FAQ

How do I use the exponent function in Excel?

Type =EXP(number) for e to a power, or =base^exponent for any other base. Example: =EXP(2) returns 7.3890561 and =5^2 returns 25.

What does EXP mean in Excel?

It is the exponential function with base e and the inverse of LN.

How do I fit an exponential curve to data?

Use GROWTH for fitted or predicted y-values or LOGEST for the coefficients m and b; both need positive y-values.

How do I do ∑ in Excel?

Use =SUM(range), for example =SUM(A2:A10).

Sources

• Microsoft Support, EXP function (read 2026-11-07)
• Microsoft Support, POWER function
• Microsoft Support, GROWTH function
• Microsoft Support, LOGEST function
• Microsoft Support, SUM function (read 2026-11-07)