1diff --git a/DOCS.md b/DOCS.md
  2index 4ef6754..ffb14e2 100644
  3--- a/DOCS.md
  4+++ b/DOCS.md
  5@@ -836,6 +836,28 @@
  6 @param values -  Array of potential value to return. Required. May be a reference to a cell or an individual value. 
  7 @constructor
  8 ```
  9+
 10+### ADDRESS 
 11+
 12+```
 13+  Returns a text representation of a cell address based on the row, column, and sheet. 
 14+@param row - Row of cell address. 
 15+@param column - Column of cell address 
 16+@param {number} absoluteVsRelativeMode - [OPTIONAL - default is 1] Should return a relative(A1, vs $A$1) or absolute address. 1 is row and column absolute (e.g. $A$1), 2 is row absolute and column relative (e.g. A$1), 3 is row relative and column absolute (e.g. $A1), 4 is row and column relative (e.g. A1). 
 17+@param {boolean} useA1Notation - [OPTIONAL - default is TRUE] Should use A1 notation. 
 18+@param sheet - [OPTIONAL] Sheet name to use in address. 
 19+@returns {string} 
 20+@constructor
 21+```
 22+
 23+### COLUMNS 
 24+
 25+```
 26+  Gets the number of columns in a specified array or range. 
 27+@param value - The array of range to consider. 
 28+@returns {number} 
 29+@constructor
 30+```
 31 ## Math
 32 
 33 
 34diff --git a/TODO.md b/TODO.md
 35index f2d42bb..5f6f938 100644
 36--- a/TODO.md
 37+++ b/TODO.md
 38@@ -23,7 +23,6 @@ For example `=#N/A` should force an error to be thrown inside the cell.
 39 Many of these formulas can be written by allowing the Sheet and Parser to return Cell objects in addition to primitive types. There are some memory issues with doing this. If a user calls something like `ISNA(A1:A99999)` we really only need the first cell. So we should return cell objects in some cases, but it would be easier in most cases to have context aware formulas, so if they need a cell, or a reference, we simply skip looking up a reference, and instead return a reference, or just a single cell. One way to do this would be to have formula functions, and then on the side have formula args. So before we lookup a large range of cells, we can check to see if it needs all of them, or if it just cares about the first one. So for `ISNA` we could look at `FormulaArgs.ISNA[0]` to get `Value` so we know that it needs only a single argument that is not an array, so if we call it with `ISNA(A1:A99999)`, it would really only lookup `A1`. This might be premature optimization however.
 40 
 41 * CELL - Requires changes to Parser/Sheet so that the raw cell is returned to the function. The raw cell should contain all information necessary for returning specified info.
 42-* COLUMNS
 43 * HLOOKUP
 44 * INDEX
 45 * INDIRECT
 46diff --git a/dist/Formulas/AllFormulas.js b/dist/Formulas/AllFormulas.js
 47index e6d28ab..db5ef61 100644
 48--- a/dist/Formulas/AllFormulas.js
 49+++ b/dist/Formulas/AllFormulas.js
 50@@ -102,6 +102,7 @@ exports.ISFORMULA = Info_1.ISFORMULA;
 51 var Lookup_1 = require("./Lookup");
 52 exports.CHOOSE = Lookup_1.CHOOSE;
 53 exports.ADDRESS = Lookup_1.ADDRESS;
 54+exports.COLUMNS = Lookup_1.COLUMNS;
 55 var Convert_1 = require("./Convert");
 56 exports.TO_DATE = Convert_1.TO_DATE;
 57 exports.TO_DOLLARS = Convert_1.TO_DOLLARS;
 58diff --git a/dist/Formulas/Lookup.js b/dist/Formulas/Lookup.js
 59index a746362..713ef5e 100644
 60--- a/dist/Formulas/Lookup.js
 61+++ b/dist/Formulas/Lookup.js
 62@@ -4,6 +4,7 @@ var ArgsChecker_1 = require("../Utilities/ArgsChecker");
 63 var Errors_1 = require("../Errors");
 64 var TypeConverter_1 = require("../Utilities/TypeConverter");
 65 var Filter_1 = require("../Utilities/Filter");
 66+var Cell_1 = require("../Cell");
 67 /**
 68  * Returns an element from a list of choices based on index.
 69  * @param index - Which choice to return. Index starts at 1.
 70@@ -25,6 +26,18 @@ var CHOOSE = function (index) {
 71     return data[i - 1];
 72 };
 73 exports.CHOOSE = CHOOSE;
 74+/**
 75+ * Returns a text representation of a cell address based on the row, column, and sheet.
 76+ * @param row - Row of cell address.
 77+ * @param column - Column of cell address
 78+ * @param {number} absoluteVsRelativeMode - [OPTIONAL - default is 1] Should return a relative(A1, vs $A$1) or absolute address. 1 is row and
 79+ * column absolute (e.g. $A$1), 2 is row absolute and column relative (e.g. A$1), 3 is row relative and column absolute
 80+ * (e.g. $A1), 4 is row and column relative (e.g. A1).
 81+ * @param {boolean} useA1Notation - [OPTIONAL - default is TRUE] Should use A1 notation.
 82+ * @param sheet - [OPTIONAL] Sheet name to use in address.
 83+ * @returns {string}
 84+ * @constructor
 85+ */
 86 var ADDRESS = function (row, column, absoluteVsRelativeMode, useA1Notation, sheet) {
 87     if (absoluteVsRelativeMode === void 0) { absoluteVsRelativeMode = 1; }
 88     if (useA1Notation === void 0) { useA1Notation = true; }
 89@@ -114,3 +127,33 @@ var ADDRESS = function (row, column, absoluteVsRelativeMode, useA1Notation, shee
 90     }
 91 };
 92 exports.ADDRESS = ADDRESS;
 93+/**
 94+ * Gets the number of columns in a specified array or range.
 95+ * @param value - The array of range to consider.
 96+ * @returns {number}
 97+ * @constructor
 98+ */
 99+var COLUMNS = function (value) {
100+    ArgsChecker_1.ArgsChecker.checkLength(arguments, 1, "COLUMNS");
101+    if (value instanceof Array) {
102+        if (value.length === 0) {
103+            throw new Errors_1.RefError("Reference does not exist.");
104+        }
105+        else if (value.length === 1) {
106+            return 1;
107+        }
108+        if (value[0] instanceof Cell_1.Cell) {
109+            var start = value[0];
110+            var end = value[value.length - 1];
111+            return end.getColumn() - start.getColumn() + 1; // counting columns inclusively
112+        }
113+        else {
114+            // if the array passed in is just values, assume that each value is a column.
115+            return value.length;
116+        }
117+    }
118+    else {
119+        return 1;
120+    }
121+};
122+exports.COLUMNS = COLUMNS;
123diff --git a/src/Formulas/AllFormulas.ts b/src/Formulas/AllFormulas.ts
124index 55cc548..fe28789 100644
125--- a/src/Formulas/AllFormulas.ts
126+++ b/src/Formulas/AllFormulas.ts
127@@ -102,7 +102,8 @@ import {
128 } from "./Info";
129 import {
130   CHOOSE,
131-  ADDRESS
132+  ADDRESS,
133+  COLUMNS
134 } from "./Lookup";
135 import {
136   TO_DATE,
137@@ -507,5 +508,6 @@ export {
138   TO_PERCENT,
139   TO_TEXT,
140   ISFORMULA,
141-  ADDRESS
142+  ADDRESS,
143+  COLUMNS
144 }
145\ No newline at end of file
146diff --git a/src/Formulas/Lookup.ts b/src/Formulas/Lookup.ts
147index 9d829f5..6c188b7 100644
148--- a/src/Formulas/Lookup.ts
149+++ b/src/Formulas/Lookup.ts
150@@ -2,7 +2,7 @@ import {
151   ArgsChecker
152 } from "../Utilities/ArgsChecker";
153 import {
154-  NumError, ValueError
155+  NumError, RefError, ValueError
156 } from "../Errors";
157 import {
158   TypeConverter
159@@ -10,6 +10,7 @@ import {
160 import {
161   Filter
162 } from "../Utilities/Filter";
163+import {Cell} from "../Cell";
164 
165 
166 /**
167@@ -29,7 +30,18 @@ let CHOOSE = function (index, ...values) {
168   return data[i-1];
169 };
170 
171-
172+/**
173+ * Returns a text representation of a cell address based on the row, column, and sheet.
174+ * @param row - Row of cell address.
175+ * @param column - Column of cell address
176+ * @param {number} absoluteVsRelativeMode - [OPTIONAL - default is 1] Should return a relative(A1, vs $A$1) or absolute address. 1 is row and
177+ * column absolute (e.g. $A$1), 2 is row absolute and column relative (e.g. A$1), 3 is row relative and column absolute
178+ * (e.g. $A1), 4 is row and column relative (e.g. A1).
179+ * @param {boolean} useA1Notation - [OPTIONAL - default is TRUE] Should use A1 notation.
180+ * @param sheet - [OPTIONAL] Sheet name to use in address.
181+ * @returns {string}
182+ * @constructor
183+ */
184 let ADDRESS = function (row, column, absoluteVsRelativeMode = 1, useA1Notation = true, sheet?) {
185   ArgsChecker.checkLengthWithin(arguments, 2, 5, "ADDRESS");
186   row = TypeConverter.firstValueAsNumber(row);
187@@ -120,7 +132,37 @@ let ADDRESS = function (row, column, absoluteVsRelativeMode = 1, useA1Notation =
188   }
189 };
190 
191+
192+/**
193+ * Gets the number of columns in a specified array or range.
194+ * @param value - The array of range to consider.
195+ * @returns {number}
196+ * @constructor
197+ */
198+let COLUMNS = function (value) {
199+  ArgsChecker.checkLength(arguments, 1, "COLUMNS");
200+  if (value instanceof Array) {
201+    if (value.length === 0) {
202+      throw new RefError("Reference does not exist.");
203+    } else if (value.length === 1) {
204+      return 1;
205+    }
206+    if (value[0] instanceof Cell) {
207+      let start = value[0];
208+      let end = value[value.length - 1];
209+      return end.getColumn() - start.getColumn() + 1; // counting columns inclusively
210+    } else {
211+      // if the array passed in is just values, assume that each value is a column.
212+      return value.length;
213+    }
214+  } else {
215+    return 1;
216+  }
217+};
218+
219+
220 export {
221   CHOOSE,
222-  ADDRESS
223+  ADDRESS,
224+  COLUMNS
225 }
226\ No newline at end of file
227diff --git a/tests/Formulas/LookupTest.ts b/tests/Formulas/LookupTest.ts
228index 672d344..6b31b5f 100644
229--- a/tests/Formulas/LookupTest.ts
230+++ b/tests/Formulas/LookupTest.ts
231@@ -1,6 +1,7 @@
232 import {
233   CHOOSE,
234-  ADDRESS
235+  ADDRESS,
236+  COLUMNS
237 } from "../../src/Formulas/Lookup";
238 import * as ERRORS from "../../src/Errors";
239 import {
240@@ -8,6 +9,9 @@ import {
241   test,
242   assertEquals
243 } from "../Utils/Asserts";
244+import {
245+  Cell
246+} from "../../src/Cell";
247 
248 
249 test("CHOOSE", function(){
250@@ -63,3 +67,57 @@ test("ADDRESS", function(){
251     ADDRESS(1, -2, 1);
252   }, ERRORS.VALUE_ERROR);
253 });
254+
255+
256+test("COLUMNS", function(){
257+  assertEquals(COLUMNS(1), 1);
258+  assertEquals(COLUMNS("str"), 1);
259+  assertEquals(COLUMNS(false), 1);
260+  assertEquals(COLUMNS(Cell.BuildFrom("A1", "str")), 1);
261+  assertEquals(COLUMNS([
262+    Cell.BuildFrom("A1", "str"),
263+    Cell.BuildFrom("A2", "str"),
264+    Cell.BuildFrom("A3", "str"),
265+    Cell.BuildFrom("A4", "str"),
266+    Cell.BuildFrom("A5", "str"),
267+    Cell.BuildFrom("A6", "str"),
268+    Cell.BuildFrom("A7", "str"),
269+    Cell.BuildFrom("A8", "str"),
270+    Cell.BuildFrom("B1", "str"),
271+    Cell.BuildFrom("B2", "str"),
272+    Cell.BuildFrom("B3", "str"),
273+    Cell.BuildFrom("B4", "str"),
274+    Cell.BuildFrom("B5", "str"),
275+    Cell.BuildFrom("B6", "str"),
276+    Cell.BuildFrom("B7", "str"),
277+    Cell.BuildFrom("B8", "str"),
278+    Cell.BuildFrom("C1", "str"),
279+    Cell.BuildFrom("C2", "str"),
280+    Cell.BuildFrom("C3", "str"),
281+    Cell.BuildFrom("C4", "str"),
282+    Cell.BuildFrom("C5", "str")
283+  ]), 3);
284+  assertEquals(COLUMNS([
285+    Cell.BuildFrom("A1", "str"),
286+    Cell.BuildFrom("A2", "str"),
287+    Cell.BuildFrom("A3", "str"),
288+    Cell.BuildFrom("A4", "str"),
289+    Cell.BuildFrom("A5", "str"),
290+    Cell.BuildFrom("A6", "str"),
291+    Cell.BuildFrom("A7", "str"),
292+    Cell.BuildFrom("A8", "str"),
293+    Cell.BuildFrom("B1", "str")
294+  ]), 2);
295+  assertEquals(COLUMNS([
296+    Cell.BuildFrom("A1", "str"),
297+    Cell.BuildFrom("A2", "str"),
298+    Cell.BuildFrom("A3", "str")
299+  ]), 1);
300+  assertEquals(COLUMNS([1, 2, 3, 4]), 4);
301+  catchAndAssertEquals(function() {
302+    COLUMNS.apply(this, []);
303+  }, ERRORS.NA_ERROR);
304+  catchAndAssertEquals(function() {
305+    COLUMNS([]);
306+  }, ERRORS.REF_ERROR);
307+});
308diff --git a/tests/SheetFormulaTest.ts b/tests/SheetFormulaTest.ts
309index 23c45de..5ab35da 100644
310--- a/tests/SheetFormulaTest.ts
311+++ b/tests/SheetFormulaTest.ts
312@@ -1032,8 +1032,16 @@ test("Sheet ADDRESS", function(){
313   assertFormulaEquals('=ADDRESS(2170, 2, 4, true, "SheetOne")', "SheetOne!B2170");
314 });
315 
316+test("Sheet COLUMNS", function(){
317+  assertFormulaEquals('=COLUMNS(1)', 1);
318+  assertFormulaEquals('=COLUMNS([1, 2, 3, 4])', 4);
319+  assertFormulaEquals('=COLUMNS(M1)', 1);
320+  assertFormulaEquals('=COLUMNS(B1:M44)', 12);
321+});
322+
323 test("Sheet parsing error", function(){
324   assertFormulaEqualsError('= 10e', PARSE_ERROR);
325+  assertFormulaEqualsError('= SUM(', PARSE_ERROR);
326 });
327 
328 test("Sheet *", function(){