diff --git a/frontend/editor/src/proprietary/components/shared/stripeCheckout/StripeCheckout.tsx b/frontend/editor/src/proprietary/components/shared/stripeCheckout/StripeCheckout.tsx
index 8b3826d264..6cf6818b7e 100644
--- a/frontend/editor/src/proprietary/components/shared/stripeCheckout/StripeCheckout.tsx
+++ b/frontend/editor/src/proprietary/components/shared/stripeCheckout/StripeCheckout.tsx
@@ -19,6 +19,7 @@ import { useCheckoutSession } from "@app/components/shared/stripeCheckout/hooks/
 import { EmailStage } from "@app/components/shared/stripeCheckout/stages/EmailStage";
 import { PlanSelectionStage } from "@app/components/shared/stripeCheckout/stages/PlanSelectionStage";
 import { CapacityStage } from "@app/components/shared/stripeCheckout/stages/CapacityStage";
+import { serversForUsers } from "@app/components/shared/stripeCheckout/utils/capacity";
 import { PaymentStage } from "@app/components/shared/stripeCheckout/stages/PaymentStage";
 import { SuccessStage } from "@app/components/shared/stripeCheckout/stages/SuccessStage";
 import { ErrorStage } from "@app/components/shared/stripeCheckout/stages/ErrorStage";
@@ -115,7 +116,13 @@ const StripeCheckout: React.FC<StripeCheckoutProps> = ({
   // Plan selection handler
   const handlePlanSelect = (period: "monthly" | "yearly") => {
     checkoutState.setSelectedPeriod(period);
-    navigation.goToStage(sellsCapacity ? "capacity" : "payment");
+    if (sellsCapacity) {
+      // Arrive on the capacity an installation already needs rather than on a blocked "1".
+      checkoutState.setServerQuantity(serversForUsers(minimumSeats));
+      navigation.goToStage("capacity");
+      return;
+    }
+    navigation.goToStage("payment");
   };
 
   // Close handler
diff --git a/frontend/editor/src/proprietary/components/shared/stripeCheckout/stages/CapacityStage.tsx b/frontend/editor/src/proprietary/components/shared/stripeCheckout/stages/CapacityStage.tsx
index a1415bb439..bfed8470d4 100644
--- a/frontend/editor/src/proprietary/components/shared/stripeCheckout/stages/CapacityStage.tsx
+++ b/frontend/editor/src/proprietary/components/shared/stripeCheckout/stages/CapacityStage.tsx
@@ -8,6 +8,7 @@ import {
   USERS_PER_SERVER,
   SELF_SERVE_MAX_SERVERS,
   usersForServers,
+  serversForUsers,
   shouldOfferEnterprise,
 } from "@app/components/shared/stripeCheckout/utils/capacity";
 
@@ -45,8 +46,9 @@ export const CapacityStage: React.FC<CapacityStageProps> = ({
   const total = unitPrice * serverQuantity;
 
   // Never sell less capacity than is already in use; reducing capacity happens at renewal rather
-  // than by stranding accounts that already exist.
-  const minServers = Math.max(1, Math.ceil(currentUsers / USERS_PER_SERVER));
+  // than by stranding accounts that already exist. The stage is entered pre-seeded to this minimum,
+  // so the guard below only fires if a caller passes something lower.
+  const minServers = serversForUsers(currentUsers);
   const belowCurrentUsage = serverQuantity < minServers;
   const offerEnterprise = shouldOfferEnterprise(serverQuantity);
 
diff --git a/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.test.ts b/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.test.ts
index b608f8a19b..b7b94b9fe0 100644
--- a/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.test.ts
+++ b/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.test.ts
@@ -4,6 +4,7 @@ import {
   SELF_SERVE_MAX_SERVERS,
   ENTERPRISE_ADVISORY_USERS,
   usersForServers,
+  serversForUsers,
   shouldOfferEnterprise,
 } from "@app/components/shared/stripeCheckout/utils/capacity";
 
@@ -20,6 +21,25 @@ describe("usersForServers", () => {
   });
 });
 
+describe("serversForUsers", () => {
+  it("rounds part-full servers up", () => {
+    expect(serversForUsers(1)).toBe(1);
+    expect(serversForUsers(USERS_PER_SERVER)).toBe(1);
+    expect(serversForUsers(USERS_PER_SERVER + 1)).toBe(2);
+    expect(serversForUsers(240)).toBe(3);
+  });
+
+  it("never returns zero servers", () => {
+    // Checkout seeds the stepper from this, and a zero would render a blocked stage.
+    expect(serversForUsers(0)).toBe(1);
+    expect(serversForUsers(-5)).toBe(1);
+  });
+
+  it("round-trips with usersForServers", () => {
+    expect(serversForUsers(usersForServers(4))).toBe(4);
+  });
+});
+
 describe("shouldOfferEnterprise", () => {
   it("stays quiet for a small purchase", () => {
     expect(shouldOfferEnterprise(1)).toBe(false);
diff --git a/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.ts b/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.ts
index d5eaf2ccbe..b96b4dba22 100644
--- a/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.ts
+++ b/frontend/editor/src/proprietary/components/shared/stripeCheckout/utils/capacity.ts
@@ -18,6 +18,11 @@ export const SELF_SERVE_MAX_SERVERS = 5;
 /** Resulting capacity at which an enterprise quote is also worth offering. */
 export const ENTERPRISE_ADVISORY_USERS = 1000;
 
+/** Servers needed to cover a given number of users. Always at least one. */
+export function serversForUsers(users: number): number {
+  return Math.max(1, Math.ceil(Math.max(0, users) / USERS_PER_SERVER));
+}
+
 /** Users covered by a given number of servers. */
 export function usersForServers(servers: number): number {
   return Math.max(1, servers) * USERS_PER_SERVER;