1diff --git a/src/RawFormulas/RawFormulas.ts b/src/RawFormulas/RawFormulas.ts
  2index 37ea38e..d506dae 100644
  3--- a/src/RawFormulas/RawFormulas.ts
  4+++ b/src/RawFormulas/RawFormulas.ts
  5@@ -255,9 +255,88 @@ var ROUNDUP = function (...values) {
  6   return Math.ceil(n * Math.pow(10, d)) / Math.pow(10, d);
  7 };
  8 
  9+/**
 10+ * Returns a conditional sum across a range.
 11+ * @param values[0] The range which is tested against criterion.
 12+ * @param values[1] The pattern or test to apply to range. If the range to check against contains text, this must be a
 13+ * string. It can be a comparison based string (e.g. "=1", "<1", ">=1") or it can be a wild-card string, in which *
 14+ * matches any number of characters, and ? matches the next character. Both ? and * can be escaped by placing a ~ in
 15+ * front of them.
 16+ * @param values[2] (optional) The range to be summed, if different from range.
 17+ * @returns {number}
 18+ * @constructor
 19+ */
 20+var SUMIF = function (...values) {
 21+  checkArgumentsAtWithin(values, 2, 3);
 22+  var range = values[0];
 23+  var criteria = values[1];
 24+  var sumRange = null;
 25+  if (values.length === 3) {
 26+    sumRange = values[2];
 27+  }
 28+  // Default criteria does nothing
 29+  var criteriaEvaluation = function (x) : boolean {
 30+    return false;
 31+  };
 32+
 33+
 34+  if (typeof criteria === "number") {
 35+    criteriaEvaluation = function (x) : boolean {
 36+      return x === criteria;
 37+    };
 38+  } else if (typeof criteria === "string") {
 39+    // https://regex101.com/r/c2hxAZ/6
 40+    var comparisonMatches = criteria.match(/(^<=|^>=|^=|^>|^<)\s*(-?[0-9]+([,.][0-9]+)?)\s*$/);
 41+    if (comparisonMatches !== null && comparisonMatches.length >= 4 && comparisonMatches[2] !== undefined) {
 42+      criteriaEvaluation = function (x) : boolean {
 43+        return eval(x + criteria);
 44+      };
 45+      if (comparisonMatches[1] === "=") {
 46+        criteriaEvaluation = function (x) : boolean {
 47+          return eval(x + "===" + comparisonMatches[2]);
 48+        };
 49+      }
 50+    } else if (criteria.match(/\*|\~\*|\?|\~\?/) !== null) {
 51+      // Regular string
 52+      var matches = criteria.match(/\*|\~\*|\?|\~\?/);
 53+      if (matches !== null) {
 54+        criteriaEvaluation = function (x) : boolean {
 55+          try {
 56+            // http://stackoverflow.com/questions/26246601/wildcard-string-comparison-in-javascript
 57+            return new RegExp("^" + criteria.split("*").join(".*") + "$").test(x);
 58+          } catch (e) {
 59+            return false;
 60+          }
 61+        };
 62+      } else {
 63+        criteriaEvaluation = function (x) : boolean {
 64+          return x === criteria;
 65+        };
 66+      }
 67+    } else {
 68+      criteriaEvaluation = function (x) : boolean {
 69+        return x === criteria;
 70+      };
 71+    }
 72+  }
 73+
 74+  var sum = 0;
 75+  for (var i = 0; i < range.length; i++) {
 76+    var x = range[i];
 77+    if (sumRange && i > sumRange.length-1) {
 78+      continue;
 79+    }
 80+    if (values.length === 2 && valueCanCoerceToNumber(x) && criteriaEvaluation(x)) {
 81+      sum = sum + x;
 82+    } else if (values.length === 3 && valueCanCoerceToNumber(sumRange[i]) && criteriaEvaluation(x)) {
 83+      sum = sum + sumRange[i];
 84+    }
 85+  }
 86+  return sum;
 87+};
 88+
 89 var SPLIT = Formula["SPLIT"];
 90 var SQRTPI = Formula["SQRTPI"];
 91-var SUMIF = Formula["SUMIF"];
 92 var SUMPRODUCT = Formula["SUMPRODUCT"];
 93 var SUMSQ = Formula["SUMSQ"];
 94 var SUMX2MY2 = Formula["SUMX2MY2"];
 95diff --git a/tests/FormulasTest.ts b/tests/FormulasTest.ts
 96index 48d1eb1..8e805dd 100644
 97--- a/tests/FormulasTest.ts
 98+++ b/tests/FormulasTest.ts
 99@@ -1099,7 +1099,45 @@ catchAndAssertEquals(function() {
100 }, ERRORS.NA_ERROR);
101 
102 
103-assertEquals(SUMIF([1, 5, 10], ">2"), 15);
104+// Test SUMIF
105+assertEquals(SUMIF([1, 5, 10], 5), 5);
106+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], 5), 20);
107+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], 10), 10);
108+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], ">5"), 10);
109+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "=5"), 20);
110+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "=1"), 1);
111+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "=     1  "), 1);
112+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], ">0"), 31);
113+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], ">=5"), 30);
114+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "<10"), 21);
115+assertEquals(SUMIF([1, 5, 5, 5, 10, 5, 44], "<=10"), 31);
116+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], ">4.99"), 30);
117+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "<4.99"), 1);
118+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "=     1.0.0  "), 0);
119+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "=>5"), 0);
120+assertEquals(SUMIF([1, 5, 5, 5, 10, 5], "==5"), 0);
121+assertEquals(SUMIF(["m", "m", 3, 11, true], "m"), 0);
122+assertEquals(SUMIF(["m", "p", "m"], "m", [1, 1, 1]), 2);
123+assertEquals(SUMIF(["p", "p", "p"], "m", [1, 1, 1]), 0);
124+assertEquals(SUMIF(["p", "p", "p"], "", [1, 1, 1]), 0);
125+assertEquals(SUMIF(["p", "p", "p"], "*", [1, 1, 1]), 3);
126+assertEquals(SUMIF(["mom", "pop", "pap"], "*o*", [1, 1, 1]), 2);
127+assertEquals(SUMIF(["mom", "pop", "pap"], "*a*", [1, 1, 1]), 1);
128+assertEquals(SUMIF(["mom", "pop", "pap"], "p*p", [1, 1, 1]), 2);
129+assertEquals(SUMIF(["mom", "pop", "pap"], "p*p", [1, 1, 1]), 2);
130+assertEquals(SUMIF(["mom", "pop", "pap"], "p*p", [1, 1,]), 1);
131+assertEquals(SUMIF(["pop", "pap"], "p*p", [1, 2, 4]), 3);
132+assertEquals(SUMIF([0, 1, 0, 1], "=1", [1, 2, 4, 8]), 10);
133+catchAndAssertEquals(function() {
134+  SUMIF([0, 1, 0, 1]);
135+}, ERRORS.NA_ERROR);
136+catchAndAssertEquals(function() {
137+  SUMIF();
138+}, ERRORS.NA_ERROR);
139+catchAndAssertEquals(function() {
140+  SUMIF([], "=1", [], true);
141+}, ERRORS.NA_ERROR);
142+
143 
144 assertEquals(SUMPRODUCT([1, 5, 10]), 16);
145 
146diff --git a/tests/SheetFormulaTest.ts b/tests/SheetFormulaTest.ts
147index 1d30336..30039a0 100644
148--- a/tests/SheetFormulaTest.ts
149+++ b/tests/SheetFormulaTest.ts
150@@ -441,7 +441,7 @@ testFormula('=SQRTPI(9)', 5.317361552716548);
151 testFormula('=SUM(10, 10)', 20);
152 
153 // Test SUMIF
154-testFormula('=SUMIF([1, 5, 10], ">2")', 15);
155+testFormula('=SUMIF([1, 5, 10], 5)', 5);
156 
157 // Test SUMPRODUCT
158 testFormula('=SUMPRODUCT([1, 5, 10])', 16);
159diff --git a/tests/SheetTest.ts b/tests/SheetTest.ts
160index 1a0d53a..d24a7b1 100644
161--- a/tests/SheetTest.ts
162+++ b/tests/SheetTest.ts
163@@ -39,7 +39,7 @@ var SUM_FORMULA = "=SUM(A1:D1, H1)";
164 var MAX_FORMULA = "=MAX(A2:J2)";
165 var MIN_FORMULA = "=MIN(A3:J3)";
166 var AVERAGE_FORMULA = "=AVERAGE(A4:J4)";
167-var SUM_IF_FORMULA = "=SUMIF(A5:J5,'>5')";
168+var SUM_IF_FORMULA = "=SUMIF(A5:J5,5)";
169 var SUM_REF_FORMULA = "=SUM(K1, K2, K3, K4)";
170 sheet.load([[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, SUM_FORMULA],
171   [-1, -10, 2, 4, 100, 1, 50, 20, 200, -100, MAX_FORMULA],
172@@ -68,7 +68,7 @@ assertEquals(AVERAGE_FORMULA.substr(1), K4.getFormula());
173 assertEquals(null, K4.getError());
174 assertArrayEquals(['A4', 'B4', 'C4', 'D4', 'E4', 'F4', 'G4', 'H4', 'I4', 'J4'], K4.getDependencies());
175 var K5 = sheet.getCell("K5");
176-assertEquals("50", K5.getValue());
177+assertEquals("0", K5.getValue());
178 assertEquals(SUM_IF_FORMULA.substr(1), K5.getFormula());
179 assertEquals(null, K5.getError());
180 assertArrayEquals(['A5', 'B5', 'C5', 'D5', 'E5', 'F5', 'G5', 'H5', 'I5', 'J5'], K5.getDependencies());