diff --git a/src/ui/windows/chat_tab.cpp b/src/ui/windows/chat_tab.cpp
index 92d77af..80c2c4d 100644
--- a/src/ui/windows/chat_tab.cpp
+++ b/src/ui/windows/chat_tab.cpp
@@ -2019,6 +2019,14 @@ void RenderChatTab(App* app)
             // Fraction of the on-chain cap used, for the radial gauge (drawn inside the input, below).
             const float frac = kBodyMaxBytes > 0 ? static_cast<float>(used) / kBodyMaxBytes : 0.0f;
 
+            // How this message chunks on-chain (mirrors buildOutgoingMessage): the hex ciphertext is
+            // (plaintext + the 17-byte secretstream tag) * 2; ≤512 hex fits one memo output, otherwise it
+            // splits into 510-hex chunks (512 minus a 2-char part index) — all carried in ONE transaction.
+            const int chatMsgParts = [&]() -> int {
+                const std::size_t hexLen = (static_cast<std::size_t>(used) + 17) * 2;
+                return hexLen <= 512 ? 1 : static_cast<int>((hexLen + 509) / 510);   // ceil(hexLen/510)
+            }();
+
             // Input row: [emoji] [input] [Send]. The input's TOP is pinned 10px below the message box and
             // it grows DOWNWARD as it gets taller (the thread above shrinks), so the row bottom stays put.
             const float rowY   = boxMax.y + composerAreaH - composerBoxH;
@@ -2129,14 +2137,33 @@ void RenderChatTab(App* app)
                     gdl->AddCircleFilled(ImVec2(ringC.x + std::cos(a1) * ringR, ringC.y + std::sin(a1) * ringR),
                                          thick * 0.6f, fillCol, 10);
                 }
+                // Always-visible part count beside the gauge once the message spans >1 memo output, so it's
+                // clear how it chunks on-chain (it's still ONE transaction). Full explanation on hover.
+                if (chatMsgParts > 1 && !overCap) {
+                    ImFont* cf = ImGui::GetFont();
+                    const float cfsz = std::max(10.0f, lineH * 0.42f);
+                    char buf[24];
+                    std::snprintf(buf, sizeof buf, "%d %s", chatMsgParts, TR("chat_parts_label"));
+                    const ImVec2 tsz = cf->CalcTextSizeA(cfsz, FLT_MAX, 0.0f, buf);
+                    gdl->AddText(cf, cfsz, ImVec2(ringC.x - ringR - 6.0f * tdp - tsz.x, ringC.y - tsz.y * 0.5f),
+                                 material::WithAlpha(material::OnSurface(), 150), buf);
+                }
                 // Exact count on hover (progressive disclosure; over-cap prefixes a label).
                 const float hitR = ringR + thick;
                 if (ImGui::IsMouseHoveringRect(ImVec2(ringC.x - hitR, ringC.y - hitR),
                                                ImVec2(ringC.x + hitR, ringC.y + hitR))) {
                     std::string tip = std::to_string(used) + " / " + std::to_string(kBodyMaxBytes);
                     if (overCap) tip = std::string(TR("chat_len_over")) + "   " + tip;
+                    else if (chatMsgParts > 1) tip += "  \xC2\xB7  " + std::to_string(chatMsgParts) + " " + TR("chat_parts_label");
                     ImGui::BeginTooltip();
                     ImGui::TextUnformatted(tip.c_str());
+                    if (chatMsgParts > 1 && !overCap) {
+                        ImGui::PushStyleColor(ImGuiCol_Text, material::OnSurfaceMedium());
+                        ImGui::PushTextWrapPos(ImGui::GetFontSize() * 24.0f);
+                        ImGui::TextUnformatted(TR("chat_parts_explain"));
+                        ImGui::PopTextWrapPos();
+                        ImGui::PopStyleColor();
+                    }
                     ImGui::EndTooltip();
                 }
             }
diff --git a/src/util/i18n.cpp b/src/util/i18n.cpp
index 12dee80..6bbc893 100644
--- a/src/util/i18n.cpp
+++ b/src/util/i18n.cpp
@@ -293,6 +293,8 @@ void I18n::loadBuiltinEnglish()
         strings_["chat_export_confirm_path"] = "Will be saved to:";
         strings_["chat_export_confirm_btn"] = "Export";
         strings_["chat_len_over"] = "Message too long";
+        strings_["chat_parts_label"] = "parts";
+        strings_["chat_parts_explain"] = "This long message is sent as one transaction split into these memo parts — it arrives as quickly as a normal message.";
         strings_["chat_mute"] = "Mute";
         strings_["chat_unmute"] = "Unmute";
         strings_["chat_hide"] = "Hide";