diff --git a/frontend/src/routes/admin/cohorts/[name]/+page.svelte b/frontend/src/routes/admin/cohorts/[name]/+page.svelte
index 7273d5fc..096d3b9c 100644
--- a/frontend/src/routes/admin/cohorts/[name]/+page.svelte
+++ b/frontend/src/routes/admin/cohorts/[name]/+page.svelte
@@ -115,8 +115,8 @@
 			const opts: { user_ids: number[]; initial_balance?: string } = {
 				user_ids: [selectedUserId]
 			};
-			if (userInitialBalance.trim()) {
-				opts.initial_balance = userInitialBalance.trim();
+			if (userInitialBalance !== '') {
+				opts.initial_balance = String(userInitialBalance);
 			}
 			const result = await batchAddMembers(cohortName, opts);
 			toast.success(`Added ${result.added} member`);
@@ -137,8 +137,8 @@
 		if (emails.length === 0) return;
 		try {
 			const opts: { emails: string[]; initial_balance?: string } = { emails };
-			if (emailInitialBalance.trim()) {
-				opts.initial_balance = emailInitialBalance.trim();
+			if (emailInitialBalance !== '') {
+				opts.initial_balance = String(emailInitialBalance);
 			}
 			const result = await batchAddMembers(cohortName, opts);
 			toast.success(`Added ${result.added} members`);
@@ -167,7 +167,7 @@
 
 	async function saveEditingBalance() {
 		if (editingMemberId == null) return;
-		const value = editingBalance.trim() || null;
+		const value = editingBalance !== '' ? String(editingBalance) : null;
 		try {
 			await updateMemberInitialBalance(cohortName, editingMemberId, value);
 			const member = members.find((m) => m.id === editingMemberId);
@@ -271,6 +271,8 @@
 					</Popover.Content>
 				</Popover.Root>
 				<input
+					type="number"
+					min="0"
 					class="w-40 rounded-md border bg-background px-3 py-2 text-sm"
 					placeholder="Initial balance"
 					bind:value={userInitialBalance}
@@ -296,6 +298,8 @@
 			></textarea>
 			<div class="mt-2 flex items-center gap-2">
 				<input
+					type="number"
+					min="0"
 					class="w-40 rounded-md border bg-background px-3 py-2 text-sm"
 					placeholder="Initial balance"
 					bind:value={emailInitialBalance}
@@ -345,6 +349,8 @@
 									{#if editingMemberId === member.id}
 										<div class="flex items-center gap-1">
 											<input
+												type="number"
+												min="0"
 												class="w-28 rounded-md border bg-background px-2 py-0.5 font-mono text-xs"
 												bind:value={editingBalance}
 												placeholder="initial bal"