diff --git a/src/templates/github/milestone.ts b/src/templates/github/milestone.ts
index 0d9ec08..6321134 100644
--- a/src/templates/github/milestone.ts
+++ b/src/templates/github/milestone.ts
@@ -31,6 +31,8 @@ const template: TemplateDefinition = {
       label: 'Closed Issues',
       type: 'number' as const,
       defaultValue: 34,
+      min: 0,
+      max: 1000,
       group: 'Content' as const,
     },
     {
@@ -38,6 +40,8 @@ const template: TemplateDefinition = {
       label: 'Total Issues',
       type: 'number' as const,
       defaultValue: 42,
+      min: 0,
+      max: 1000,
       group: 'Content' as const,
     },
     {
diff --git a/src/templates/github/sponsors-goal.ts b/src/templates/github/sponsors-goal.ts
index 2251869..6820e88 100644
--- a/src/templates/github/sponsors-goal.ts
+++ b/src/templates/github/sponsors-goal.ts
@@ -33,6 +33,8 @@ const template: TemplateDefinition = {
       label: 'Raised',
       type: 'number' as const,
       defaultValue: 420,
+      min: 0,
+      max: 10000,
       group: 'Content' as const,
     },
     {
@@ -40,6 +42,8 @@ const template: TemplateDefinition = {
       label: 'Goal',
       type: 'number' as const,
       defaultValue: 1000,
+      min: 0,
+      max: 10000,
       group: 'Content' as const,
     },
     {
diff --git a/tests/templates/registry.test.ts b/tests/templates/registry.test.ts
index 9760d52..8837925 100644
--- a/tests/templates/registry.test.ts
+++ b/tests/templates/registry.test.ts
@@ -65,6 +65,17 @@ describe('Template Registry', () => {
     }
   });
 
+  it('every number field default fits inside its slider range', () => {
+    for (const t of getAllTemplates()) {
+      for (const field of t.fields.filter((f) => f.type === 'number')) {
+        const value = Number(t.defaults[field.key] ?? field.defaultValue);
+        const where = `${t.id}.${field.key}`;
+        expect(value, where).toBeGreaterThanOrEqual(field.min ?? 0);
+        expect(value, where).toBeLessThanOrEqual(field.max ?? 100);
+      }
+    }
+  });
+
   it('template IDs should be unique', () => {
     const templates = getAllTemplates();
     const ids = templates.map((t) => t.id);