diff --git a/src/table-layout.js b/src/table-layout.js
index 9a8ea81..7b9661a 100644
--- a/src/table-layout.js
+++ b/src/table-layout.js
@@ -1,10 +1,12 @@
 var _ = require('lodash');
-var Cell = require('./cell');
+(function(){
 
+var Cell = require('./cell');
 
 function makeTableLayout(rows){
   var cellRows = generateCells(rows);
   expandCells(cellRows);
+  fillInTable(cellRows);
   return cellRows;
 }
 
@@ -82,8 +84,91 @@ function maxWidth(rows){
   },0);
 }
 
+function iterateColumn(rows,col,fn,ctx){
+  for(var i = 0; i < rows.length; i++){
+    fn.call(ctx,rows[i][col],i);
+  }
+}
+  function getCell(rows,y,x){
+    return rows[y][x];
+  }
+
+  function getCellPivot(rows,x,y){
+    return rows[y][x];
+  }
+
+  function iterateRow(rows,row,fn,ctx){
+    var columns = rows[row];
+    for(var i = 0; i < columns.length; i++){
+      fn.call(ctx,columns[i],i);
+    }
+  }
+  function maxHeight(rows){
+    return rows.length;
+  }
+
 module.exports = {
   makeTableLayout:makeTableLayout,
   maxWidth:maxWidth,
-  fillInTable:fillInTable
-};
\ No newline at end of file
+  fillInTable:fillInTable,
+  computeWidths:makeComputeWidths(iterateColumn,maxWidth,'colSpan','desiredWidth',getCell),
+  computeHeights:makeComputeWidths(iterateRow,maxHeight,'rowSpan','desiredHeight',getCellPivot)
+};
+
+})();
+
+function makeComputeWidths(iterateColumn,maxWidth,colSpan,desiredWidth,getCell){
+  return function (vals,rows){
+    var width = maxWidth(rows);
+    var result = [];
+    var spanners = [];
+    for(var columnIndex = 0; columnIndex < width; columnIndex++){
+      if(!_.isNumber(vals[columnIndex])){
+        var maxDesired = 0;
+        iterateColumn(rows,columnIndex,function(cell,rowIndex){
+          if(cell[colSpan] && cell[colSpan] > 1){
+            spanners.push({row:rowIndex,column:columnIndex});
+          }
+          else {
+            maxDesired = Math.max(maxDesired,cell[desiredWidth] || 0);
+          }
+        });
+        result[columnIndex] = maxDesired;
+      }
+      else {
+        result[columnIndex] = vals[columnIndex];
+        iterateColumn(rows,columnIndex,function(cell,rowIndex) {
+          if (cell[colSpan] && cell[colSpan] > 1) {
+            spanners.push({row: rowIndex, column: columnIndex});
+          }
+        });
+      }
+    }
+    while(spanners.length){
+      var coords = spanners.pop();
+      var cell = getCell(rows,coords.row,coords.column);
+      var span = cell[colSpan];
+      var existingWidth = result[coords.column];
+      var editableCols = _.isNumber(vals[coords.column]) ? 0 : 1;
+      for(var i = 1; i < span; i ++){
+        existingWidth += 1 + result[coords.column + i];
+        if(!_.isNumber(vals[coords.column + i])){
+          editableCols++;
+        }
+      }
+      if(cell[desiredWidth] > existingWidth){
+        i = 0;
+        while(editableCols > 0 && cell[desiredWidth] > existingWidth){
+          if(!_.isNumber(vals[coords.column+i])){
+            var dif = Math.round( (cell[desiredWidth] - existingWidth) / editableCols );
+            existingWidth += dif;
+            result[coords.column + i] += dif;
+            editableCols--;
+          }
+          i++;
+        }
+      }
+    }
+    _.extend(vals,result);
+  }
+}
\ No newline at end of file
diff --git a/test/table-layout-test.js b/test/table-layout-test.js
index 95a4621..e8be7d8 100644
--- a/test/table-layout-test.js
+++ b/test/table-layout-test.js
@@ -4,6 +4,8 @@ describe('tableLayout', function () {
   var makeTableLayout = tableLayout.makeTableLayout;
   var maxWidth = tableLayout.maxWidth;
   var fillInTable = tableLayout.fillInTable;
+  var computeWidths = tableLayout.computeWidths;
+  var computeHeights = tableLayout.computeHeights;
   var chai = require('chai');
   var expect = chai.expect;
   var _ = require('lodash');
@@ -159,7 +161,192 @@ describe('tableLayout', function () {
         ['','b',{spannerFor:[1,2]}]
       ]);
     });
+  });
+
+  describe('computeWidths',function() {
+    function mc(desiredWidth, colSpan) {
+      return {desiredWidth: desiredWidth, colSpan: colSpan};
+    }
+
+    it('finds the maximum desired width of each column', function () {
+      var widths = [];
+      var cells = [
+        [mc(7), mc(3), mc(5)],
+        [mc(8), mc(5), mc(2)],
+        [mc(6), mc(9), mc(1)]
+      ];
+
+      computeWidths(widths, cells);
+
+      expect(widths).to.eql([8, 9, 5]);
+    });
+
+    it('won\'t touch hard coded values', function () {
+      var widths = [null, 3];
+      var cells = [
+        [mc(7), mc(3), mc(5)],
+        [mc(8), mc(5), mc(2)],
+        [mc(6), mc(9), mc(1)]
+      ];
+
+      computeWidths(widths, cells);
+
+      expect(widths).to.eql([8, 3, 5]);
+    });
+
+    it('assumes undefined desiredWidth is 0', function () {
+      var widths = [];
+      var cells = [[{}], [{}], [{}]];
+      computeWidths(widths, cells);
+      expect(widths).to.eql([0])
+    });
+
+    it('takes into account colSpan and wont over expand', function () {
+      var widths = [];
+      var cells = [
+        [mc(10, 2), mc(5), mc(5)],
+        [mc(5), mc(3), mc(2)],
+        [mc(4), mc(2), mc(1)]
+      ];
+      computeWidths(widths, cells);
+      expect(widths).to.eql([5, 5, 5]);
+    });
+
+    it('will expand rows involved in colSpan in a balanced way', function () {
+      var widths = [];
+      var cells = [
+        [mc(13, 2), mc(), mc(5)],
+        [mc(5), mc(5), mc(2)],
+        [mc(4), mc(2), mc(1)]
+      ];
+      computeWidths(widths, cells);
+      expect(widths).to.eql([6, 6, 5]);
+    });
+
+    it('expands across 3 cols', function () {
+      var widths = [];
+      var cells = [
+        [mc(25, 3), mc(), mc()],
+        [mc(5), mc(5), mc(2)],
+        [mc(4), mc(2), mc(1)]
+      ];
+      computeWidths(widths, cells);
+      expect(widths).to.eql([9, 9, 5]);
+    });
+
+    it('multiple spans in same table', function () {
+      var widths = [];
+      var cells = [
+        [mc(25, 3), mc(), mc()],
+        [mc(30, 3), mc(), mc()],
+        [mc(4), mc(2), mc(1)]
+      ];
+      computeWidths(widths, cells);
+      expect(widths).to.eql([11, 9, 8]);
+    });
+
+    it('spans will only edit uneditable tables',function(){
+      var widths = [null, 3];
+      var cells = [
+        [mc(20,3),mc(),mc()],
+        [mc(4),mc(20),mc(5)]
+      ];
+      computeWidths(widths, cells);
+      expect(widths).to.eql([7,3,8])
+    });
+
+    it('spans will only edit uneditable tables - first column uneditable',function(){
+      var widths = [3];
+      var cells = [
+        [mc(20,3),mc(), mc()],
+        [mc(4),   mc(3), mc(5)]
+      ];
+      computeWidths(widths, cells);
+      expect(widths).to.eql([3,7,8])
+    });
+  });
+    
+  describe('computeHeights',function(){
+    function mc(desiredHeight,colSpan){
+      return {desiredHeight:desiredHeight,rowSpan:colSpan};
+    }
+
+    it('finds the maximum desired height of each row',function(){
+      var heights = [];
+      var cells = [
+        [mc(7), mc(3), mc(5)],
+        [mc(8), mc(5), mc(2)],
+        [mc(6), mc(9), mc(1)]
+      ];
+
+      computeHeights(heights,cells);
+
+      expect(heights).to.eql([7,8,9]);
+    });
+
+    it('won\'t touch hard coded values',function(){
+      var heights = [null,3];
+      var cells = [
+        [mc(7), mc(3), mc(5)],
+        [mc(8), mc(5), mc(2)],
+        [mc(6), mc(9), mc(1)]
+      ];
+
+      computeHeights(heights,cells);
+
+      expect(heights).to.eql([7,3,9]);
+    });
+
+    it('assumes undefined desiredHeight is 0',function(){
+      var heights = [];
+      var cells = [[{},{},{}]];
+      computeHeights(heights,cells);
+      expect(heights).to.eql([0])
+    });
+
+    it('takes into account rowSpan and wont over expand',function(){
+      var heights = [];
+      var cells = [
+        [mc(10,2), mc(5), mc(5)],
+        [mc(5),    mc(3), mc(2)],
+        [mc(4),    mc(2), mc(1)]
+      ];
+      computeHeights(heights,cells);
+      expect(heights).to.eql([5,5,4]);
+    });
+
+    it('will expand rows involved in rowSpan in a balanced way',function(){
+      var heights = [];
+      var cells = [
+        [mc(13,2), mc(), mc(5)],
+        [mc(5),    mc(5), mc(2)],
+        [mc(4),    mc(2), mc(1)]
+      ];
+      computeHeights(heights,cells);
+      expect(heights).to.eql([6,6,4]);
+    });
 
+    it('expands across 3 rows',function(){
+      var heights = [];
+      var cells = [
+        [mc(25,3), mc(5), mc(4)],
+        [mc(),    mc(5), mc(2)],
+        [mc(),    mc(2), mc(1)]
+      ];
+      computeHeights(heights,cells);
+      expect(heights).to.eql([9,9,5]);
+    });
+
+    it('multiple spans in same table',function(){
+      var heights = [];
+      var cells = [
+        [mc(25,3), mc(30,3), mc(4)],
+        [mc(),     mc(),     mc(2)],
+        [mc(),     mc(),     mc(1)]
+      ];
+      computeHeights(heights,cells);
+      expect(heights).to.eql([11,9,8]);
+    });
   });
 
   /**