diff --git a/Easing/Easing.cs b/Easing/Easing.cs
index 27f598c..ee5233b 100644
--- a/Easing/Easing.cs
+++ b/Easing/Easing.cs
@@ -601,5 +601,83 @@ namespace MoonTools.Core.Easing
         public static double OutInCirc(double t) => NormalizedTime(OutInCirc, t);
         public static double OutInCirc(double time, double start, double end) => TimeRange(OutInCirc, time, start, end);
         public static double OutInCirc(double t, double b, double c, double d) => OutIn(OutCirc, InCirc, t, b, c, d);
+
+        // IN ELASTIC
+
+        // a: amplitude
+        // p: period
+
+        public static double InElasticNormalized(double t) => InElastic(t, 0, 1, 1);
+        public static double InElasticNormalized(double t, double a) => InElastic(t, 0, 1, 1, a);
+        public static double InElasticNormalized(double t, double a, double p) => InElastic(t, 0, 1, 1, a, p);
+
+        public static double InElasticTimeRange(double time, double start, double end) => start + (end - start) * InElasticNormalized((time - start) / (end - start));
+        public static double InElasticTimeRange(double time, double start, double end, double a) => start + (end - start) * InElasticNormalized((time - start) / (end - start), a);
+        public static double InElasticTimeRange(double time, double start, double end, double a, double p) => start + (end - start) * InElasticNormalized((time - start) / (end - start), a, p);
+
+        public static double InElastic(double t, double b, double c, double d, double? a = null, double? p = null)
+        {
+            CheckTime(t, d);
+
+            if (t == 0) { return b; }
+
+            t = t / d;
+
+            if (t == 1) { return b + c; }
+
+            if (!p.HasValue) { p = d * 0.3; }
+
+            double s;
+            if (!a.HasValue || a.Value < Math.Abs(c))
+            {
+                a = c;
+                s = p.Value / 4;
+            }
+            else
+            {
+                s = p.Value / (2 * Math.PI) * Math.Asin(c / a.Value);
+            }
+
+            t = t - 1;
+
+            return -(a.Value * Math.Pow(2, 10 * t) * Math.Sin((t * d - s) * (2 * Math.PI) / p.Value)) + b;
+        }
+
+        // OUT ELASTIC
+
+        public static double OutElasticNormalized(double t) => OutElastic(t, 0, 1, 1);
+        public static double OutElasticNormalized(double t, double a) => OutElastic(t, 0, 1, 1, a);
+        public static double OutElasticNormalized(double t, double a, double p) => OutElastic(t, 0, 1, 1, a, p);
+
+        public static double OutElasticTimeRange(double time, double start, double end) => start + (end - start) * OutElasticNormalized((time - start) / (end - start));
+        public static double OutElasticTimeRange(double time, double start, double end, double a) => start + (end - start) * OutElasticNormalized((time - start) / (end - start), a);
+        public static double OutElasticTimeRange(double time, double start, double end, double a, double p) => start + (end - start) * OutElasticNormalized((time - start) / (end - start), a, p);
+
+        public static double OutElastic(double t, double b, double c, double d, double? a = null, double? p = null)
+        {
+            CheckTime(t, d);
+
+            if (t == 0) { return b; }
+
+            t = t / d;
+
+            if (t == 1) { return b + c; }
+
+            if (!p.HasValue) { p = d * 0.3; }
+
+            double s;
+
+            if (!a.HasValue || a.Value < Math.Abs(c))
+            {
+                a = c;
+                s = p.Value / 4;
+            }
+            else
+            {
+                s = p.Value / (2 * Math.PI) * Math.Asin(c / a.Value);
+            }
+
+            return a.Value * Math.Pow(2, -10 * t) * Math.Sin((t * d - s) * (2 * Math.PI) / p.Value) + c + b;
+        }
     }
 }
diff --git a/Test/Easing.cs b/Test/Easing.cs
index 480cad9..17cb4ec 100644
--- a/Test/Easing.cs
+++ b/Test/Easing.cs
@@ -890,6 +890,82 @@ namespace Test
 
                 CheckDoubleArguments(Easing.OutInCirc, Easing.OutInCirc);
             }
+
+            [Test]
+            public void InElasticDefault()
+            {
+                Easing.InElasticNormalized(0.25).Should().BeApproximately(-0.0055242717280199, 0.001);
+                Easing.InElasticNormalized(0.5).Should().BeApproximately(-0.015625, 0.001);
+                Easing.InElasticNormalized(0.75).Should().BeApproximately(0.088388347648318, 0.001);
+
+                Easing.InElasticTimeRange(3, 2, 6).Should().BeApproximately(1.97790291309, 0.001);
+                Easing.InElasticTimeRange(4, 2, 6).Should().BeApproximately(1.9375, 0.001);
+                Easing.InElasticTimeRange(5, 2, 6).Should().BeApproximately(2.35355339059, 0.001);
+
+                CheckDoubleArguments(Easing.InElasticNormalized, Easing.InElasticNormalized);
+            }
+
+            [Test]
+            public void InElasticWithA()
+            {
+                Easing.InElasticNormalized(0.25, 10).Should().BeApproximately(-0.0055242717280198, 0.001);
+                Easing.InElasticNormalized(0.5, 10).Should().BeApproximately(-0.28490137405647, 0.001);
+                Easing.InElasticNormalized(0.75, 10).Should().BeApproximately(-1.4348688532209, 0.001);
+
+                Easing.InElasticTimeRange(3, 2, 6, 10).Should().BeApproximately(1.97790291309, 0.001);
+                Easing.InElasticTimeRange(4, 2, 6, 10).Should().BeApproximately(0.860394503774, 0.001);
+                Easing.InElasticTimeRange(5, 2, 6, 10).Should().BeApproximately(-3.73947541288, 0.001);
+            }
+
+            [Test]
+            public void InElasticWithAAndP()
+            {
+                Easing.InElasticNormalized(0.25, 10, 0.5).Should().BeApproximately(-0.0055242717280199, 0.001);
+                Easing.InElasticNormalized(0.5, 10, 0.5).Should().BeApproximately(0.03125, 0.001);
+                Easing.InElasticNormalized(0.75, 10, 0.5).Should().BeApproximately(-0.17677669529664, 0.001);
+
+                Easing.InElasticTimeRange(3, 2, 6, 10, 0.5).Should().BeApproximately(1.97790291309, 0.001);
+                Easing.InElasticTimeRange(4, 2, 6, 10, 0.5).Should().BeApproximately(2.125, 0.001);
+                Easing.InElasticTimeRange(5, 2, 6, 10, 0.5).Should().BeApproximately(1.29289321881, 0.001);
+            }
+
+            [Test]
+            public void OutElasticDefault()
+            {
+                Easing.OutElasticNormalized(0.25).Should().BeApproximately(0.91161165235168, 0.001);
+                Easing.OutElasticNormalized(0.5).Should().BeApproximately(1.015625, 0.001);
+                Easing.OutElasticNormalized(0.75).Should().BeApproximately(1.005524271728, 0.001);
+
+                Easing.OutElasticTimeRange(3, 2, 6).Should().BeApproximately(5.64644660941, 0.001);
+                Easing.OutElasticTimeRange(4, 2, 6).Should().BeApproximately(6.0625, 0.001);
+                Easing.OutElasticTimeRange(5, 2, 6).Should().BeApproximately(6.02209708691, 0.001);
+
+                CheckDoubleArguments(Easing.OutElasticNormalized, Easing.OutElasticNormalized);
+            }
+
+            [Test]
+            public void OutElasticWithA()
+            {
+                Easing.OutElasticNormalized(0.25, 10).Should().BeApproximately(-0.61164554851756, 0.001);
+                Easing.OutElasticNormalized(0.5, 10).Should().BeApproximately(0.74634862594353, 0.001);
+                Easing.OutElasticNormalized(0.75, 10).Should().BeApproximately(1.005524271728, 0.001);
+
+                Easing.OutElasticTimeRange(3, 2, 6, 10).Should().BeApproximately(-0.44658219407, 0.001);
+                Easing.OutElasticTimeRange(4, 2, 6, 10).Should().BeApproximately(4.98539450378, 0.001);
+                Easing.OutElasticTimeRange(5, 2, 6, 10).Should().BeApproximately(6.02209708691, 0.001);
+            }
+
+            [Test]
+            public void OutElasticWithAAndP()
+            {
+                Easing.OutElasticNormalized(0.25, 10, 0.5).Should().BeApproximately(1.1767766952966, 0.001);
+                Easing.OutElasticNormalized(0.5, 10, 0.5).Should().BeApproximately(0.96875, 0.001);
+                Easing.OutElasticNormalized(0.75, 10, 0.5).Should().BeApproximately(1.005524271728, 0.001);
+
+                Easing.OutElasticTimeRange(3, 2, 6, 10, 0.5).Should().BeApproximately(6.70710678118, 0.001);
+                Easing.OutElasticTimeRange(4, 2, 6, 10, 0.5).Should().BeApproximately(5.875, 0.001);
+                Easing.OutElasticTimeRange(5, 2, 6, 10, 0.5).Should().BeApproximately(6.02209708691, 0.001);
+            }
         }
     }
 }
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