diff --git a/css/main.css b/css/main.css
index 5c748b33f..2aeac8172 100644
--- a/css/main.css
+++ b/css/main.css
@@ -635,3 +635,9 @@ ul.pagination li.current a:hover, ul.pagination li.current a:focus {
   color:white;
 }
 
+.input-note {
+  margin-top: -10px;
+  display: block;
+  margin-bottom: 1rem;
+}
+
diff --git a/index.html b/index.html
index 0381a52b0..06859b9fc 100644
--- a/index.html
+++ b/index.html
@@ -696,7 +696,6 @@
                   <div class="row collapse">
                     <label for="amount">Amount
                       <small ng-hide="!sendForm.amount.$pristine">required</small>
-                      <i class="fi-arrow-up" title="Send all funds" ng-click="topAmount()"></i>
                       <small class="is-valid" ng-show="!sendForm.amount.$invalid && !sendForm.amount.$pristine">Valid</small>
                       <small class="has-error" ng-show="sendForm.amount.$invalid && !sendForm.amount.$pristine && !notEnoughAmount">
                         Not valid
@@ -706,9 +705,14 @@
                     <div class="small-9 columns">
                       <input type="number" id="amount" ng-disabled="loading"
                       name="amount" placeholder="Amount" ng-model="amount"
-                      min="1" max="10000000000" enough-amount required
+                      min="0.0001" max="10000000000" enough-amount required
                       autocomplete="off"
                       >
+                      <a class="small input-note" title="Send all funds"
+                        ng-show="$root.availableBalance > 0" 
+                        ng-click="topAmount(sendForm)">
+                        Use all funds ({{getAvailableAmount()}} {{$root.unitName}})
+                      </a>                      
                     </div>
                     <div class="small-3 columns">
                       <span class="postfix">{{$root.unitName}}</span>
@@ -720,13 +724,13 @@
                   Total amount for this transaction: 
                   </small>
                   <div class="totalAmount">
-                    <b>{{amount + defaultFee |number}}</b> {{$root.unitName}}
+                    <b>{{amount + defaultFee |number:4}}</b> {{$root.unitName}}
                     <small>
-                    {{ ((amount + defaultFee) * unitToBtc) |number}} BTC
+                    {{ ((amount + defaultFee) * unitToBtc) |number:4}} BTC
                     </small>
                   </div>
                   <small>
-                  Including fee of {{defaultFee|number}} {{$root.unitName}} 
+                  Including fee of {{defaultFee |number:4}} {{$root.unitName}} 
                   </small>
                 </div>
               </div>
diff --git a/js/controllers/send.js b/js/controllers/send.js
index 26c50f6aa..9d4e96cb3 100644
--- a/js/controllers/send.js
+++ b/js/controllers/send.js
@@ -267,8 +267,12 @@ angular.module('copayApp.controllers').controller('SendController',
       });
     };
 
-    $scope.topAmount = function() {
-      var maxSat = ($rootScope.availableBalance * config.unitToSatoshi).toFixed(0) - bitcore.TransactionBuilder.FEE_PER_1000B_SAT;
-      $scope.amount = maxSat / config.unitToSatoshi;
+    $scope.getAvailableAmount = function() {
+      return ((($rootScope.availableBalance * config.unitToSatoshi).toFixed(0) - bitcore.TransactionBuilder.FEE_PER_1000B_SAT) / config.unitToSatoshi);
+    };
+
+    $scope.topAmount = function(form) {
+      $scope.amount = $scope.getAvailableAmount();      
+      form.amount.$pristine = false;
     };
   });
diff --git a/js/directives.js b/js/directives.js
index 586a1ac31..fac694ddb 100644
--- a/js/directives.js
+++ b/js/directives.js
@@ -40,12 +40,12 @@ angular.module('copayApp.directives')
   .directive('enoughAmount', ['$rootScope',
     function($rootScope) {
       var bitcore = require('bitcore');
-      var feeSat = bitcore.TransactionBuilder.FEE_PER_1000B_SAT;
+      var feeSat = Number(bitcore.TransactionBuilder.FEE_PER_1000B_SAT);
       return {
         require: 'ngModel',
         link: function(scope, element, attrs, ctrl) {
           var val = function(value) {
-            var availableBalanceNum = ($rootScope.availableBalance * config.unitToSatoshi).toFixed(0);
+            var availableBalanceNum = Number(($rootScope.availableBalance * config.unitToSatoshi).toFixed(0));
             var vNum = Number((value * config.unitToSatoshi).toFixed(0)) + feeSat;
             if (typeof vNum == "number" && vNum > 0) {
               if (availableBalanceNum < vNum) {
diff --git a/test/unit/controllers/controllersSpec.js b/test/unit/controllers/controllersSpec.js
index 7dcadc715..a47c013e9 100644
--- a/test/unit/controllers/controllersSpec.js
+++ b/test/unit/controllers/controllersSpec.js
@@ -282,10 +282,23 @@ describe("Unit: Controllers", function() {
   });
 
   describe('Send Controller', function() {
-    var sendCtrl;
-    beforeEach(inject(function($controller, $rootScope) {
+    var sendCtrl, form;
+    beforeEach(inject(function($compile, $rootScope, $controller) {
       scope = $rootScope.$new();
       $rootScope.availableBalance = 123456;
+
+      var element = angular.element(
+        '<form name="form">' +
+        '<input type="number" id="amount" name="amount" placeholder="Amount" ng-model="amount" min="0.0001" max="10000000" enough-amount required>' +
+        '</form>'
+        );
+      scope.model = {
+        amount: null
+      };
+      $compile(element)(scope);
+      scope.$digest();
+      form = scope.form;
+
       sendCtrl = $controller('SendController', {
         $scope: scope,
         $modal: {},
@@ -296,8 +309,15 @@ describe("Unit: Controllers", function() {
       expect(scope.isMobile).not.to.equal(null);
     });
     it('should autotop balance correctly', function() {
-      scope.topAmount();
+      scope.topAmount(form);
+      form.amount.$setViewValue(123356);
       expect(scope.amount).to.equal(123356);
+      expect(form.amount.$invalid).to.equal(false);
+      expect(form.amount.$pristine).to.equal(false);
+    });
+    it('should return available amount', function() {
+      var amount = scope.getAvailableAmount();
+      expect(amount).to.equal(123356);
     });
   });
 
diff --git a/test/unit/directives/directivesSpec.js b/test/unit/directives/directivesSpec.js
index 882939143..ff3efc4a8 100644
--- a/test/unit/directives/directivesSpec.js
+++ b/test/unit/directives/directivesSpec.js
@@ -8,6 +8,10 @@ describe("Unit: Testing Directives", function() {
 
   beforeEach(module('copayApp.directives'));
 
+  beforeEach(function() {
+    config.unitToSatoshi = 100;
+    config.unitName = 'bits';
+  });
 
   describe('Check config', function() {
     it('unit should be set to BITS in config.js', function() {
@@ -43,41 +47,89 @@ describe("Unit: Testing Directives", function() {
   });
 
   describe('Validate Amount', function() {
-    beforeEach(inject(function($compile, $rootScope) {
-      $scope = $rootScope;
-      $rootScope.availableBalance = 1000;
-      var element = angular.element(
-        '<form name="form">' +
-        '<input type="number" id="amount" name="amount" placeholder="Amount" ng-model="amount" min="0.0001" max="10000000" enough-amount required>' +
-        '</form>'
-      );
-      $scope.model = {
-        amount: null
-      };
-      $compile(element)($scope);
-      $scope.$digest();
-      form = $scope.form;
-    }));
+    describe('Unit: bits', function() {
+      beforeEach(inject(function($compile, $rootScope) {
+        $scope = $rootScope;
+        $rootScope.availableBalance = 1000;
+        var element = angular.element(
+          '<form name="form">' +
+          '<input type="number" id="amount" name="amount" placeholder="Amount" ng-model="amount" min="0.0001" max="10000000" enough-amount required>' +
+          '</form>'
+        );
+        $scope.model = {
+          amount: null
+        };
+        $compile(element)($scope);
+        $scope.$digest();
+        form = $scope.form;
+      }));
+      it('should validate', function() {
+        form.amount.$setViewValue(100);
+        expect(form.amount.$invalid).to.equal(false);
+        form.amount.$setViewValue(800);
+        expect(form.amount.$invalid).to.equal(false);
+        form.amount.$setViewValue(900);
+        expect($scope.notEnoughAmount).to.equal(null);
+      });
 
-
-
-    it('should validate', function() {
-      form.amount.$setViewValue(100);
-      expect(form.amount.$invalid).to.equal(false);
-      form.amount.$setViewValue(900);
-      expect(form.amount.$invalid).to.equal(false);
+      it('should not validate', function() {
+        form.amount.$setViewValue(0);
+        expect(form.amount.$invalid).to.equal(true);
+        form.amount.$setViewValue(9999999999);
+        expect(form.amount.$invalid).to.equal(true);
+        form.amount.$setViewValue(901);
+        expect(form.amount.$invalid).to.equal(true);
+        form.amount.$setViewValue(1000);
+        expect(form.amount.$invalid).to.equal(true);
+        form.amount.$setViewValue(901);
+        expect($scope.notEnoughAmount).to.equal(true);
+      });
     });
 
-    it('should not validate', function() {
-      form.amount.$setViewValue(0);
-      expect(form.amount.$invalid).to.equal(true);
-      form.amount.$setViewValue(9999999999);
-      expect(form.amount.$invalid).to.equal(true);
-      form.amount.$setViewValue(901);
-      expect(form.amount.$invalid).to.equal(true);
-      form.amount.$setViewValue(1000);
-      expect(form.amount.$invalid).to.equal(true);
+    describe('Unit: BTC', function() {
+      beforeEach(inject(function($compile, $rootScope) {
+        config.unitToSatoshi = 100000000;
+        config.unitName = 'BTC';
+        $scope = $rootScope;
+        $rootScope.availableBalance = 0.04;
+        var element = angular.element(
+          '<form name="form">' +
+          '<input type="number" id="amount" name="amount" placeholder="Amount" ng-model="amount" min="0.0001" max="10000000" enough-amount required>' +
+          '</form>'
+        );
+        $scope.model = {
+          amount: null
+        };
+        $compile(element)($scope);
+        $scope.$digest();
+        form = $scope.form;
+      }));
+
+      it('should validate', function() {
+        form.amount.$setViewValue(0.01);
+        expect($scope.notEnoughAmount).to.equal(null);
+        expect(form.amount.$invalid).to.equal(false);
+        form.amount.$setViewValue(0.039);
+        expect($scope.notEnoughAmount).to.equal(null);
+        expect(form.amount.$invalid).to.equal(false);
+      });
+
+      it('should not validate', function() {
+        form.amount.$setViewValue(0.03999);
+        expect($scope.notEnoughAmount).to.equal(true);
+        expect(form.amount.$invalid).to.equal(true);
+        form.amount.$setViewValue(0);
+        expect(form.amount.$invalid).to.equal(true);
+        form.amount.$setViewValue(0.0);
+        expect(form.amount.$invalid).to.equal(true);
+        form.amount.$setViewValue(0.05);
+        expect($scope.notEnoughAmount).to.equal(true);
+        expect(form.amount.$invalid).to.equal(true);
+
+      });
+
     });
+
   });
 
   describe('Contact directive', function() {
diff --git a/test/unit/services/servicesSpec.js b/test/unit/services/servicesSpec.js
index 388007e06..2c29c78ea 100644
--- a/test/unit/services/servicesSpec.js
+++ b/test/unit/services/servicesSpec.js
@@ -5,7 +5,13 @@
 //
 var sinon = require('sinon');
 
+beforeEach(function() {
+  config.unitToSatoshi = 100;
+  config.unitName = 'bits';
+});
+
 describe('Check config', function() {
+
   it('unit should be set to BITS in config.js', function() {
     expect(config.unitToSatoshi).to.equal(100);
     expect(config.unitName).to.equal('bits');