diff --git a/web-admin/src/features/projects/settings/ProjectDevSlotsSettings.svelte b/web-admin/src/features/projects/settings/ProjectDevSlotsSettings.svelte
new file mode 100644
index 00000000000..c99325b35a3
--- /dev/null
+++ b/web-admin/src/features/projects/settings/ProjectDevSlotsSettings.svelte
@@ -0,0 +1,201 @@
+<script lang="ts">
+  import {
+    createAdminServiceGetProject,
+    createAdminServiceUpdateProject,
+    getAdminServiceGetProjectQueryKey,
+    type RpcStatus,
+  } from "@rilldata/web-admin/client";
+  import { parseUpdateProjectError } from "@rilldata/web-admin/features/projects/settings/errors";
+  import SettingsContainer from "@rilldata/web-admin/features/organizations/settings/SettingsContainer.svelte";
+  import {
+    ALL_SLOTS,
+    SLOT_TIERS,
+  } from "@rilldata/web-admin/features/projects/status/overview/slots-utils";
+  import * as DropdownMenu from "@rilldata/web-common/components/dropdown-menu";
+  import CaretDownIcon from "@rilldata/web-common/components/icons/CaretDownIcon.svelte";
+  import CaretUpIcon from "@rilldata/web-common/components/icons/CaretUpIcon.svelte";
+  import InfoCircle from "@rilldata/web-common/components/icons/InfoCircle.svelte";
+  import Tooltip from "@rilldata/web-common/components/tooltip/Tooltip.svelte";
+  import TooltipContent from "@rilldata/web-common/components/tooltip/TooltipContent.svelte";
+  import { eventBus } from "@rilldata/web-common/lib/event-bus/event-bus";
+  import { queryClient } from "@rilldata/web-common/lib/svelte-query/globalQueryClient";
+  import type { AxiosError } from "axios";
+
+  let { organization, project }: { organization: string; project: string } =
+    $props();
+
+  const updateProjectMutation = createAdminServiceUpdateProject();
+  let projectResp = $derived(
+    createAdminServiceGetProject(organization, project),
+  );
+
+  let currentDevSlots = $derived(
+    Number($projectResp.data?.project?.devSlots) || 0,
+  );
+
+  let dropdownOpen = $state(false);
+
+  function formatSize(slots: number): { units: string; instance: string } {
+    const tier = SLOT_TIERS.find((t) => t.slots === slots);
+    const instance = tier?.instance ?? `${slots * 4}GiB / ${slots}vCPU`;
+    const unitLabel = slots === 1 ? "Compute unit" : "Compute units";
+    return { units: `${slots} ${unitLabel}`, instance };
+  }
+
+  // Dev deployments may use a single slot, which isn't in ALL_SLOTS (that list
+  // starts at 2 for production sizing).
+  let slotOptions = $derived(
+    (() => {
+      const slots = new Set<number>([1, ...ALL_SLOTS]);
+      if (currentDevSlots > 0) slots.add(currentDevSlots);
+      return [...slots].sort((a, b) => a - b);
+    })(),
+  );
+
+  let current = $derived(
+    currentDevSlots > 0 ? formatSize(currentDevSlots) : null,
+  );
+
+  async function handleSelect(slots: number) {
+    if (slots === currentDevSlots) return;
+    try {
+      await $updateProjectMutation.mutateAsync({
+        org: organization,
+        project,
+        data: { devSlots: String(slots) },
+      });
+      await queryClient.refetchQueries({
+        queryKey: getAdminServiceGetProjectQueryKey(organization, project),
+      });
+      const { units, instance } = formatSize(slots);
+      eventBus.emit("notification", {
+        message: `Default dev cluster size updated to ${units} — ${instance}`,
+      });
+    } catch (err) {
+      const parsed = parseUpdateProjectError(err as AxiosError<RpcStatus>);
+      eventBus.emit("notification", {
+        message: parsed.message || "Failed to update dev cluster size",
+        type: "error",
+      });
+    }
+  }
+</script>
+
+<SettingsContainer title="Development deployments">
+  <p>
+    Sets the default cluster size allocated to new development deployments.
+    Development deployments are ephemeral — they spin up when a user opens a
+    branch editor and expire after 6 hours of inactivity.
+  </p>
+
+  <div class="field">
+    <div class="label-row">
+      <span class="label">Default cluster size</span>
+      <Tooltip location="right" alignment="middle" distance={8}>
+        <div class="text-fg-tertiary flex items-center">
+          <InfoCircle size="12px" />
+        </div>
+        <TooltipContent slot="tooltip-content">
+          1 Compute unit = 4 GiB RAM, 1 vCPU
+        </TooltipContent>
+      </Tooltip>
+    </div>
+    <div class="row">
+      <span class="value">
+        {#if $updateProjectMutation.isPending}
+          <span class="text-fg-tertiary">Updating…</span>
+        {:else if current}
+          <span class="units">{current.units}</span>
+          <span class="separator">—</span>
+          <span class="instance">{current.instance}</span>
+        {:else}
+          <span class="text-fg-tertiary">Not set</span>
+        {/if}
+      </span>
+
+      <DropdownMenu.Root bind:open={dropdownOpen}>
+        <DropdownMenu.Trigger
+          class="change-trigger {dropdownOpen ? 'open' : ''}"
+          disabled={$updateProjectMutation.isPending}
+        >
+          <span>Select cluster size</span>
+          {#if dropdownOpen}
+            <CaretUpIcon size="12px" />
+          {:else}
+            <CaretDownIcon size="12px" />
+          {/if}
+        </DropdownMenu.Trigger>
+        <DropdownMenu.Content align="end" class="w-[260px]">
+          {#each slotOptions as slots (slots)}
+            {@const opt = formatSize(slots)}
+            <DropdownMenu.Item
+              class="flex flex-col items-start gap-0.5 {slots ===
+              currentDevSlots
+                ? 'bg-surface-subtle'
+                : ''}"
+              onclick={() => handleSelect(slots)}
+            >
+              <span class="text-xs font-medium text-fg-primary">
+                {opt.units}
+              </span>
+              <span class="text-[11px] text-fg-tertiary">
+                {opt.instance}
+              </span>
+            </DropdownMenu.Item>
+          {/each}
+        </DropdownMenu.Content>
+      </DropdownMenu.Root>
+    </div>
+  </div>
+</SettingsContainer>
+
+<style lang="postcss">
+  p {
+    @apply text-sm text-fg-tertiary;
+  }
+
+  .field {
+    @apply mt-4 flex flex-col gap-y-1;
+  }
+
+  .label-row {
+    @apply flex items-center gap-x-1;
+  }
+
+  .label {
+    @apply text-sm font-medium text-fg-primary;
+  }
+
+  .row {
+    @apply flex items-center justify-between gap-4 py-1;
+  }
+
+  .value {
+    @apply text-sm text-fg-primary flex items-baseline gap-x-2;
+  }
+
+  .units {
+    @apply font-medium;
+  }
+
+  .separator {
+    @apply text-fg-tertiary;
+  }
+
+  .instance {
+    @apply text-fg-secondary;
+  }
+
+  :global(.change-trigger) {
+    @apply flex items-center gap-1 rounded-sm border px-2.5 py-1 text-sm text-fg-primary transition-colors;
+    @apply hover:bg-surface-hover;
+  }
+
+  :global(.change-trigger.open) {
+    @apply bg-surface-hover;
+  }
+
+  :global(.change-trigger[disabled]) {
+    @apply opacity-50 cursor-not-allowed;
+  }
+</style>
diff --git a/web-admin/src/routes/[organization]/[project]/-/settings/+page.svelte b/web-admin/src/routes/[organization]/[project]/-/settings/+page.svelte
index d736d6b4a14..23839d6bda9 100644
--- a/web-admin/src/routes/[organization]/[project]/-/settings/+page.svelte
+++ b/web-admin/src/routes/[organization]/[project]/-/settings/+page.svelte
@@ -7,6 +7,7 @@
   import DangerZone from "@rilldata/web-admin/components/settings/DangerZone.svelte";
   import DeleteProject from "@rilldata/web-admin/features/projects/settings/DeleteProject.svelte";
   import HibernateProject from "@rilldata/web-admin/features/projects/settings/HibernateProject.svelte";
+  import ProjectDevSlotsSettings from "@rilldata/web-admin/features/projects/settings/ProjectDevSlotsSettings.svelte";
   import ProjectNameSettings from "@rilldata/web-admin/features/projects/settings/ProjectNameSettings.svelte";
   import ProjectVisibilitySettings from "@rilldata/web-admin/features/projects/settings/ProjectVisibilitySettings.svelte";
 
@@ -34,6 +35,8 @@
   </div>
 </SettingsContainer>
 
+<ProjectDevSlotsSettings {organization} {project} />
+
 <div class="danger-zone-section">
   <h3 class="danger-zone-title">Danger Zone</h3>
   <DangerZone>