| IF | The value based on a condition you specify. |
| IFERROR | (2007) The value based on an error condition you specify. |
| IFNA | (2013) The boolean value depending if the value is #N/A. |
| IMABS* | The absolute value (modulus) of a complex number. |
| IMAGINARY* | The imaginary coefficient of a complex number. |
| IMARGUMENT* | The theta argument (an angle in radians). |
| IMCONJUGATE* | The complex conjugate of a complex number. |
| IMCOS* | The cosine of a complex number. |
| IMCOSH | (2013) The hyperbolic cosine of a complex number. |
| IMCOT | (2013) The cotangent of a complex number. |
| IMCSC | (2013) The cosecant of a complex number. |
| IMCSCH | (2013) The hyperbolic cosecant of a complex number. |
| IMDIV* | The quotient of two complex numbers. |
| IMEXP* | The exponential of a complex number. |
| IMLN* | The natural logarithm of a complex number. |
| IMLOG10* | The base-10 logarithm of a complex number. |
| IMLOG2* | The base-2 logarithm of a complex number. |
| IMPOWER* | The complex number raised to an integer number. |
| IMPRODUCT* | The product of two or more complex numbers. |
| IMREAL* | The real coefficient of a complex number. |
| IMSEC | (2013) The secant of a complex number. |
| IMSECH | (2013) The hyperbolic secant of a complex number. |
| IMSIN* | The sine of a complex number. |
| IMSINH | (2013) The hyperbolic sine of a complex number. |
| IMSQRT* | The square root of a complex number. |
| IMSUB* | The difference of two complex numbers. |
| IMSUM* | The sum of two or more complex numbers. |
| IMTAN | (2013) The tangent of a complex number. |
| INDEX | The value from a table, based on an index number. |
| INDIRECT | The text string of the contents of a given cell reference. |
| INFO | The text string returning useful information about the environment. |
| INT | The number rounded down to the nearest integer. |
| INTERCEPT | The intersection with the y-axis using a linear regression plotted through known values. |
| INTRATE* | The interest rate for a security held to maturity. |
| IPMT | The interest paid for a given period in a series of equal cash flows at regular intervals. |
| IRR | The interest rate for a series of unequal cash flows at regular intervals. |
| ISBLANK | The boolean value depending if the value is blank. |
| ISERR | The boolean value depending if the value is an error (not N/A). |
| ISERROR | The boolean value depending if the value is an error. |
| ISEVEN* | The boolean value depending if the value is an even number. |
| ISFORMULA | (2013) The boolean value depending if the cell contains a formula. |
| ISLOGICAL | The boolean value depending if the value is True or False. |
| ISNA | The boolean value depending if the value is N/A. |
| ISNONTEXT | The boolean value depending if the value is non text. |
| ISNUMBER | The boolean value depending if the value is a number. |
| ISO.CEILING | (2010) The number rounded up to the nearest integer or multiple of significance. |
| ISODD* | The boolean value depending if the value is an odd number. |
| ISOWEEKNUM | (2013 - WEEKNUM) The number of the ISO week of the year for a given date. Week number according to the European standard. |
| ISPMT | The interest paid in a given period in a series of equal cash flows at regular intervals (incorrectly). |
| ISREF | The boolean value depending if the value is a cell reference. |
| ISTEXT | The boolean value depending if the value is text. |
