diff --git a/common/script/index.js b/common/script/index.js
index 6a3558f937..9bb5c8312e 100644
--- a/common/script/index.js
+++ b/common/script/index.js
@@ -13,6 +13,14 @@ api = module.exports = {};
 
 api.i18n = i18n;
 
+import statHelpers from './statHelpers.js'
+
+api.maxLevel = statHelpers.maxLevel;
+api.capByLevel = statHelpers.capByLevel;
+api.maxHealth = statHelpers.maxHealth;
+api.tnl = statHelpers.tnl;
+api.diminishingReturns = statHelpers.diminishingReturns;
+
 $w = api.$w = function(s) {
   return s.split(' ');
 };
@@ -182,63 +190,6 @@ api.shouldDo = function(day, dailyTask, options) {
   }
 };
 
-
-/*
-  ------------------------------------------------------
-  Level cap
-  ------------------------------------------------------
- */
-
-api.maxLevel = 100;
-
-api.capByLevel = function(lvl) {
-  if (lvl > api.maxLevel) {
-    return api.maxLevel;
-  } else {
-    return lvl;
-  }
-};
-
-
-/*
-  ------------------------------------------------------
-  Health cap
-  ------------------------------------------------------
- */
-
-api.maxHealth = 50;
-
-
-/*
-  ------------------------------------------------------
-  Scoring
-  ------------------------------------------------------
- */
-
-api.tnl = function(lvl) {
-  return Math.round(((Math.pow(lvl, 2) * 0.25) + (10 * lvl) + 139.75) / 10) * 10;
-};
-
-
-/*
-  A hyperbola function that creates diminishing returns, so you can't go to infinite (eg, with Exp gain).
-  {max} The asymptote
-  {bonus} All the numbers combined for your point bonus (eg, task.value * user.stats.int * critChance, etc)
-  {halfway} (optional) the point at which the graph starts bending
- */
-
-api.diminishingReturns = function(bonus, max, halfway) {
-  if (halfway == null) {
-    halfway = max / 2;
-  }
-  return max * (bonus / (bonus + halfway));
-};
-
-api.monod = function(bonus, rateOfIncrease, max) {
-  return rateOfIncrease * max * bonus / (rateOfIncrease * bonus + max);
-};
-
-
 /*
 Preen history for users with > 7 history entries
 This takes an infinite array of single day entries [day day day day day...], and turns it into a condensed array
diff --git a/common/script/statHelpers.js b/common/script/statHelpers.js
new file mode 100644
index 0000000000..005663d741
--- /dev/null
+++ b/common/script/statHelpers.js
@@ -0,0 +1,55 @@
+/*
+  ------------------------------------------------------
+  Level cap
+  ------------------------------------------------------
+ */
+
+const maxLevel = 100;
+
+function capByLevel (lvl) {
+  if (lvl > maxLevel) {
+    return maxLevel;
+  } else {
+    return lvl;
+  }
+}
+
+/*
+  ------------------------------------------------------
+  Health cap
+  ------------------------------------------------------
+ */
+
+const maxHealth = 50;
+
+/*
+  ------------------------------------------------------
+  Scoring
+  ------------------------------------------------------
+ */
+
+function tnl (lvl) {
+  return Math.round((Math.pow(lvl, 2) * 0.25 + 10 * lvl + 139.75) / 10) * 10;
+}
+
+/*
+  A hyperbola function that creates diminishing returns, so you can't go to infinite (eg, with Exp gain).
+  {max} The asymptote
+  {bonus} All the numbers combined for your point bonus (eg, task.value * user.stats.int * critChance, etc)
+  {halfway} (optional) the point at which the graph starts bending
+ */
+
+function diminishingReturns (bonus, max, halfway) {
+  if (halfway === null) {
+    halfway = max / 2;
+  }
+  return max * (bonus / (bonus + halfway));
+}
+
+export default {
+  maxLevel,
+  capByLevel,
+  maxHealth,
+  tnl,
+  diminishingReturns,
+};
diff --git a/test/common/statHelpers.test.js b/test/common/statHelpers.test.js
new file mode 100644
index 0000000000..d757d40381
--- /dev/null
+++ b/test/common/statHelpers.test.js
@@ -0,0 +1,58 @@
+var sinon = require('sinon');
+var chai = require("chai")
+chai.use(require("sinon-chai"))
+var expect = chai.expect
+
+var shared = require('../../common/script/index.js');
+
+describe('helper functions used in stat calculations', function() {
+
+  var HEALTH_CAP = 50;
+  var LEVEL_CAP = 100;
+  var LEVEL = 57;
+  var BONUS = 600;
+  var MAXIMUM = 200;
+  var HALFWAY = 75;
+
+  it('provides a maximum Health value', function() {
+    expect(shared.maxHealth).to.eql(HEALTH_CAP);
+  });
+
+  describe('maximum level cap', function() {
+    it('returns a maximum level for attribute gain', function() {
+      expect(shared.maxLevel).to.eql(LEVEL_CAP);
+    });
+
+    it('returns level given if below cap', function() {
+      expect(shared.capByLevel(LEVEL)).to.eql(LEVEL);
+    });
+
+    it('returns level given if equal to cap', function() {
+      expect(shared.capByLevel(LEVEL_CAP)).to.eql(LEVEL_CAP);
+    });
+
+    it('returns level cap if above cap', function() {
+      expect(shared.capByLevel(LEVEL_CAP + LEVEL)).to.eql(LEVEL_CAP);
+    });
+  });
+
+  describe('Experience to next level', function() {
+    it('increases Experience target from one level to the next', function() {
+      expect(shared.tnl(LEVEL + 1)).to.be.greaterThan(shared.tnl(LEVEL));
+    });
+  });
+
+  describe('diminishing returns', function() {
+    it('provides a value under the maximum, given a bonus and maximum', function() {
+      expect(shared.diminishingReturns(BONUS,MAXIMUM)).to.be.lessThan(MAXIMUM);
+    });
+
+    it('provides a value under the maximum, given a bonus, maximum, and halfway point', function() {
+      expect(shared.diminishingReturns(BONUS,MAXIMUM,HALFWAY)).to.be.lessThan(MAXIMUM);
+    });
+
+    it('provides a different curve if a halfway point is defined', function() {
+      expect(shared.diminishingReturns(BONUS,MAXIMUM,HALFWAY)).to.not.eql(shared.diminishingReturns(BONUS,MAXIMUM));
+    });
+  });
+});