diff --git a/src/components/ui/checkbox.stories.tsx b/src/components/ui/checkbox.stories.tsx
index 22d27f48..159a5bc9 100644
--- a/src/components/ui/checkbox.stories.tsx
+++ b/src/components/ui/checkbox.stories.tsx
@@ -80,4 +80,34 @@ export const Disabled: Story = {
       expect(canvas.getByText("Email me when the build completes")).toBeInTheDocument()
     })
   },
-}
\ No newline at end of file
+}
+export const ExtraSmall: Story = {
+  render: () => renderCheckbox({ size: "xs", defaultChecked: true }),
+  parameters: {
+    zephyr: { testCaseId: "SW-T5693" },
+  },
+  play: async ({ canvasElement, step }) => {
+    const canvas = within(canvasElement)
+
+    await step("xs checkbox box is 14px", async () => {
+      const cb = canvas.getByRole("checkbox")
+      expect(cb).toHaveAttribute("data-size", "xs")
+      expect(Math.round(cb.getBoundingClientRect().height)).toBe(14)
+    })
+  },
+}
+
+export const Large: Story = {
+  render: () => renderCheckbox({ size: "lg", defaultChecked: true }),
+  parameters: {
+    zephyr: { testCaseId: "SW-T5694" },
+  },
+  play: async ({ canvasElement, step }) => {
+    const canvas = within(canvasElement)
+
+    await step("lg checkbox box is 20px", async () => {
+      const cb = canvas.getByRole("checkbox")
+      expect(Math.round(cb.getBoundingClientRect().height)).toBe(20)
+    })
+  },
+}
diff --git a/src/components/ui/checkbox.tsx b/src/components/ui/checkbox.tsx
index cc790fa8..10e904d0 100644
--- a/src/components/ui/checkbox.tsx
+++ b/src/components/ui/checkbox.tsx
@@ -1,32 +1,49 @@
+import { cva, type VariantProps } from "class-variance-authority"
 import { CheckIcon } from "lucide-react"
 import { Checkbox as CheckboxPrimitive } from "radix-ui"
 import * as React from "react"
 
 import { cn } from "@/lib/utils"
 
+const checkboxVariants = cva(
+  "group/checkbox peer relative flex shrink-0 items-center justify-center rounded-[4px] border border-input bg-card transition-colors outline-none group-has-disabled/field:opacity-50 after:absolute after:-inset-x-3 after:-inset-y-2 focus-visible:border-ring focus-visible:shadow-focus disabled:cursor-not-allowed disabled:opacity-50 aria-invalid:border-destructive aria-invalid:shadow-focus aria-invalid:aria-checked:border-primary dark:bg-input/30 dark:aria-invalid:border-destructive/50 data-checked:border-primary data-checked:bg-primary data-checked:text-primary-foreground dark:data-checked:bg-primary",
+  {
+    variants: {
+      // Box scale (SW-2591): default stays 16 (no visual change); xs 14 / lg 20.
+      size: {
+        xs: "size-3.5",
+        sm: "size-4",
+        default: "size-4",
+        lg: "size-5",
+      },
+    },
+    defaultVariants: {
+      size: "default",
+    },
+  }
+)
 
 function Checkbox({
   className,
+  size,
   ...props
-}: React.ComponentProps<typeof CheckboxPrimitive.Root>) {
+}: React.ComponentProps<typeof CheckboxPrimitive.Root> &
+  VariantProps<typeof checkboxVariants>) {
   return (
     <CheckboxPrimitive.Root
       data-slot="checkbox"
-      className={cn(
-        "peer relative flex size-4 shrink-0 items-center justify-center rounded-[4px] border border-input bg-card transition-colors outline-none group-has-disabled/field:opacity-50 after:absolute after:-inset-x-3 after:-inset-y-2 focus-visible:border-ring focus-visible:shadow-focus disabled:cursor-not-allowed disabled:opacity-50 aria-invalid:border-destructive aria-invalid:shadow-focus aria-invalid:aria-checked:border-primary dark:bg-input/30 dark:aria-invalid:border-destructive/50 data-checked:border-primary data-checked:bg-primary data-checked:text-primary-foreground dark:data-checked:bg-primary",
-        className
-      )}
+      data-size={size ?? "default"}
+      className={cn(checkboxVariants({ size }), className)}
       {...props}
     >
       <CheckboxPrimitive.Indicator
         data-slot="checkbox-indicator"
-        className="grid place-content-center text-current transition-none [&>svg]:size-3.5"
+        className="grid place-content-center text-current transition-none [&>svg]:size-3.5 group-data-[size=xs]/checkbox:[&>svg]:size-3 group-data-[size=lg]/checkbox:[&>svg]:size-4"
       >
-        <CheckIcon
-        />
+        <CheckIcon />
       </CheckboxPrimitive.Indicator>
     </CheckboxPrimitive.Root>
   )
 }
 
-export { Checkbox }
+export { Checkbox, checkboxVariants }
diff --git a/src/components/ui/radio-group.stories.tsx b/src/components/ui/radio-group.stories.tsx
index 595974f0..b2e01007 100644
--- a/src/components/ui/radio-group.stories.tsx
+++ b/src/components/ui/radio-group.stories.tsx
@@ -96,4 +96,44 @@ export const DisabledOption: Story = {
       expect(canvas.getByRole("radio", { name: /Enterprise/i })).toBeDisabled()
     })
   },
-}
\ No newline at end of file
+}
+export const ExtraSmall: Story = {
+  render: () => (
+    <RadioGroup size="xs" defaultValue="team" aria-label="Plan">
+      <RadioGroupItem value="starter" aria-label="Starter" />
+      <RadioGroupItem value="team" aria-label="Team" />
+    </RadioGroup>
+  ),
+  parameters: {
+    zephyr: { testCaseId: "SW-T5695" },
+  },
+  play: async ({ canvasElement, step }) => {
+    const canvas = within(canvasElement)
+
+    await step("xs radio box is 14px (group size flows to items)", async () => {
+      const item = canvas.getAllByRole("radio")[0]
+      expect(item).toHaveAttribute("data-size", "xs")
+      expect(Math.round(item.getBoundingClientRect().height)).toBe(14)
+    })
+  },
+}
+
+export const Large: Story = {
+  render: () => (
+    <RadioGroup size="lg" defaultValue="team" aria-label="Plan">
+      <RadioGroupItem value="starter" aria-label="Starter" />
+      <RadioGroupItem value="team" aria-label="Team" />
+    </RadioGroup>
+  ),
+  parameters: {
+    zephyr: { testCaseId: "SW-T5696" },
+  },
+  play: async ({ canvasElement, step }) => {
+    const canvas = within(canvasElement)
+
+    await step("lg radio box is 20px", async () => {
+      const item = canvas.getAllByRole("radio")[0]
+      expect(Math.round(item.getBoundingClientRect().height)).toBe(20)
+    })
+  },
+}
diff --git a/src/components/ui/radio-group.tsx b/src/components/ui/radio-group.tsx
index 174c3c12..83d3d1be 100644
--- a/src/components/ui/radio-group.tsx
+++ b/src/components/ui/radio-group.tsx
@@ -1,44 +1,72 @@
 "use client"
 
+import { cva, type VariantProps } from "class-variance-authority"
 import { RadioGroup as RadioGroupPrimitive } from "radix-ui"
 import * as React from "react"
 
 import { cn } from "@/lib/utils"
 
+type RadioSize = "xs" | "sm" | "default" | "lg"
+
+const RadioGroupContext = React.createContext<{ size?: RadioSize }>({})
+
 function RadioGroup({
   className,
+  size,
   ...props
-}: React.ComponentProps<typeof RadioGroupPrimitive.Root>) {
+}: React.ComponentProps<typeof RadioGroupPrimitive.Root> & { size?: RadioSize }) {
   return (
-    <RadioGroupPrimitive.Root
-      data-slot="radio-group"
-      className={cn("grid w-full gap-2", className)}
-      {...props}
-    />
+    <RadioGroupContext.Provider value={{ size: size ?? "default" }}>
+      <RadioGroupPrimitive.Root
+        data-slot="radio-group"
+        className={cn("grid w-full gap-2", className)}
+        {...props}
+      />
+    </RadioGroupContext.Provider>
   )
 }
 
+const radioGroupItemVariants = cva(
+  "group/radio-group-item peer relative flex aspect-square shrink-0 rounded-full border border-input bg-card outline-none after:absolute after:-inset-x-3 after:-inset-y-2 focus-visible:border-ring focus-visible:shadow-focus disabled:cursor-not-allowed disabled:opacity-50 aria-invalid:border-destructive aria-invalid:shadow-focus aria-invalid:aria-checked:border-primary dark:bg-input/30 dark:aria-invalid:border-destructive/50 data-checked:border-primary data-checked:bg-primary data-checked:text-primary-foreground dark:data-checked:bg-primary",
+  {
+    variants: {
+      // Box scale (SW-2591): default stays 16 (no visual change); xs 14 / lg 20.
+      size: {
+        xs: "size-3.5",
+        sm: "size-4",
+        default: "size-4",
+        lg: "size-5",
+      },
+    },
+    defaultVariants: {
+      size: "default",
+    },
+  }
+)
+
 function RadioGroupItem({
   className,
+  size,
   ...props
-}: React.ComponentProps<typeof RadioGroupPrimitive.Item>) {
+}: React.ComponentProps<typeof RadioGroupPrimitive.Item> &
+  VariantProps<typeof radioGroupItemVariants>) {
+  const context = React.useContext(RadioGroupContext)
+  const resolved = size ?? context.size ?? "default"
   return (
     <RadioGroupPrimitive.Item
       data-slot="radio-group-item"
-      className={cn(
-        "group/radio-group-item peer relative flex aspect-square size-4 shrink-0 rounded-full border border-input bg-card outline-none after:absolute after:-inset-x-3 after:-inset-y-2 focus-visible:border-ring focus-visible:shadow-focus disabled:cursor-not-allowed disabled:opacity-50 aria-invalid:border-destructive aria-invalid:shadow-focus aria-invalid:aria-checked:border-primary dark:bg-input/30 dark:aria-invalid:border-destructive/50 data-checked:border-primary data-checked:bg-primary data-checked:text-primary-foreground dark:data-checked:bg-primary",
-        className
-      )}
+      data-size={resolved}
+      className={cn(radioGroupItemVariants({ size: resolved }), className)}
       {...props}
     >
       <RadioGroupPrimitive.Indicator
         data-slot="radio-group-indicator"
-        className="flex size-4 items-center justify-center"
+        className="flex size-full items-center justify-center"
       >
-        <span className="absolute top-1/2 left-1/2 size-2 -translate-x-1/2 -translate-y-1/2 rounded-full bg-primary-foreground" />
+        <span className="absolute top-1/2 left-1/2 size-2 -translate-x-1/2 -translate-y-1/2 rounded-full bg-primary-foreground group-data-[size=xs]/radio-group-item:size-1.5 group-data-[size=lg]/radio-group-item:size-2.5" />
       </RadioGroupPrimitive.Indicator>
     </RadioGroupPrimitive.Item>
   )
 }
 
-export { RadioGroup, RadioGroupItem }
+export { RadioGroup, RadioGroupItem, radioGroupItemVariants }