diff --git a/frontend/src/utils/streamCost.ts b/frontend/src/utils/streamCost.ts
new file mode 100644
index 0000000..41c18ac
--- /dev/null
+++ b/frontend/src/utils/streamCost.ts
@@ -0,0 +1,5 @@
+export function estimateStreamCost(amount: number, durationDays: number): { xlm: number; usdc: number } {
+  const feeXlm = 0.00002 * durationDays; // Base Stellar fee per day
+  const totalXlm = feeXlm + (amount / 10_000_000);
+  return { xlm: Math.round(totalXlm * 1e7) / 1e7, usdc: Math.round(amount / 1e7 * 100) / 100 };
+}