diff --git a/src/utils/unit-conversion.utils.ts b/src/utils/unit-conversion.utils.ts
index 6cd186f..766b150 100644
--- a/src/utils/unit-conversion.utils.ts
+++ b/src/utils/unit-conversion.utils.ts
@@ -18,7 +18,11 @@ const STROOP_DIVISOR = new Decimal(STROOPS_PER_XLM);
  * stroopsToXlm("10000000")    // "1.0000000"
  */
 export function stroopsToXlm(stroops: bigint | string): string {
-    return new Decimal(stroops.toString()).dividedBy(STROOP_DIVISOR).toFixed(STROOP_DECIMALS);
+  const dec = new Decimal(stroops.toString());
+  if (dec.isNaN()) {
+    throw new TypeError(`Invalid stroops amount: ${stroops}`);
+  }
+  return dec.dividedBy(STROOP_DIVISOR).toFixed(STROOP_DECIMALS);
 }
 
 /**
@@ -35,5 +39,9 @@ export function stroopsToXlm(stroops: bigint | string): string {
  * xlmToStroops(1)             // 10_000_000n
  */
 export function xlmToStroops(xlm: string | number): bigint {
-    return BigInt(new Decimal(xlm).times(STROOP_DIVISOR).toFixed(0, Decimal.ROUND_DOWN));
+  const dec = new Decimal(xlm);
+  if (dec.isNaN()) {
+    throw new TypeError(`Invalid XLM amount: ${xlm}`);
+  }
+  return BigInt(dec.times(STROOP_DIVISOR).toFixed(0, Decimal.ROUND_DOWN));
 }
diff --git a/tests/unit/utils/unit-conversion.test.ts b/tests/unit/utils/unit-conversion.test.ts
new file mode 100644
index 0000000..c231876
--- /dev/null
+++ b/tests/unit/utils/unit-conversion.test.ts
@@ -0,0 +1,73 @@
+import { stroopsToXlm, xlmToStroops } from "../../../src/utils/unit-conversion.utils";
+
+describe("Unit Conversion Utilities", () => {
+  describe("stroopsToXlm", () => {
+    it('should convert 0 stroops (bigint) to "0.0000000"', () => {
+      expect(stroopsToXlm(0n)).toBe("0.0000000");
+    });
+
+    it('should convert 0 stroops (string) to "0.0000000"', () => {
+      expect(stroopsToXlm("0")).toBe("0.0000000");
+    });
+
+    it('should convert 1 stroop (bigint) to "0.0000001"', () => {
+      expect(stroopsToXlm(1n)).toBe("0.0000001");
+    });
+
+    it('should convert 1 stroop (string) to "0.0000001"', () => {
+      expect(stroopsToXlm("1")).toBe("0.0000001");
+    });
+
+    it('should convert 10,000,000 stroops to "1.0000000"', () => {
+      expect(stroopsToXlm(10000000n)).toBe("1.0000000");
+      expect(stroopsToXlm("10000000")).toBe("1.0000000");
+    });
+
+    it("should convert 100,000 XLM (1,000,000,000,000 stroops) correctly", () => {
+      expect(stroopsToXlm(1000000000000n)).toBe("100000.0000000");
+      expect(stroopsToXlm("1000000000000")).toBe("100000.0000000");
+    });
+
+    it("should handle fractional representation without precision loss", () => {
+      expect(stroopsToXlm(123456789n)).toBe("12.3456789");
+    });
+
+    it("should throw an Error for non-numeric input strings", () => {
+      expect(() => stroopsToXlm("invalid")).toThrow();
+    });
+  });
+
+  describe("xlmToStroops", () => {
+    it("should convert 0 XLM (number) to 0n", () => {
+      expect(xlmToStroops(0)).toBe(0n);
+    });
+
+    it("should convert 0 XLM (string) to 0n", () => {
+      expect(xlmToStroops("0")).toBe(0n);
+    });
+
+    it("should convert 0.0000001 XLM to 1n stroop", () => {
+      expect(xlmToStroops(0.0000001)).toBe(1n);
+      expect(xlmToStroops("0.0000001")).toBe(1n);
+    });
+
+    it("should convert 1 XLM to 10,000,000n stroops", () => {
+      expect(xlmToStroops(1)).toBe(10000000n);
+      expect(xlmToStroops("1")).toBe(10000000n);
+    });
+
+    it("should convert 100,000 XLM to 1,000,000,000,000n stroops", () => {
+      expect(xlmToStroops(100000)).toBe(1000000000000n);
+      expect(xlmToStroops("100000")).toBe(1000000000000n);
+    });
+
+    it("should prevent floating-point precision loss for tricky decimals", () => {
+      expect(xlmToStroops("12.3456789")).toBe(123456789n);
+      expect(xlmToStroops(0.1 + 0.2)).toBe(3000000n);
+    });
+
+    it("should throw an Error for non-numeric input strings", () => {
+      expect(() => xlmToStroops("invalid")).toThrow();
+    });
+  });
+});