diff --git a/docs/API.md b/docs/API.md
index 8b3437f..52a48ec 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -91,7 +91,9 @@ json {   "source": "jbd_bms",   "connected": true,   "soc": 70,   "voltage": 13.
 
 Additional fields may include:
 
-text cell_count cell_voltages cell_min_voltage cell_max_voltage cell_delta_mv runtime_hours ntc_count cells_valid 
+text cell_count cell_voltages cell_min_voltage cell_max_voltage cell_delta_mv runtime_hours ntc_count cells_valid
+
+`runtime_hours` is discharge runtime from the ESP32 status payload. The WebUI derives charging time-to-full from `capacity_ah`, `remaining_ah`, and positive incoming `current` without changing the API shape. 
 
 ---
 
diff --git a/docs/project-state.md b/docs/project-state.md
index 1e91353..7264d7e 100644
--- a/docs/project-state.md
+++ b/docs/project-state.md
@@ -67,7 +67,7 @@ Shows:
 - Battery SOC
 - Voltage
 - Current
-- Estimated runtime
+- Estimated runtime / charging time-to-full
 - Temperature sensors
 - Relay controls
 - Network status
diff --git a/firmware/esp32/overland-controller/overland-controller.ino b/firmware/esp32/overland-controller/overland-controller.ino
index 328e638..cd70193 100644
--- a/firmware/esp32/overland-controller/overland-controller.ino
+++ b/firmware/esp32/overland-controller/overland-controller.ino
@@ -79,7 +79,7 @@ input{width:100%;border:1px solid var(--line);border-radius:12px;padding:12px;ba
         <div class="kpi">
           <div><div class="muted">Voltage</div><div class="num" id="voltage">--</div></div>
           <div><div class="muted">Current</div><div class="num" id="current">--</div></div>
-          <div><div class="muted">Runtime</div><div class="num" id="runtime">--</div></div>
+          <div><div class="muted" id="runtimeLabel">Runtime</div><div class="num" id="runtime">--</div></div>
         </div>
       </section>
 
@@ -233,13 +233,28 @@ input{width:100%;border:1px solid var(--line);border-radius:12px;padding:12px;ba
 const $=id=>document.getElementById(id);
 function fmt(n,d=1){return typeof n==="number"?n.toFixed(d):"--"}
 function temp(v){return typeof v==="number"?fmt(v,1)+"°F":"Offline"}
-function runtimeText(b){
-  if(!b.connected) return "--";
-  if(typeof b.runtime_hours==="number" && b.runtime_hours>0) return fmt(b.runtime_hours,1)+"h";
-  if(typeof b.current==="number" && b.current<-.1 && typeof b.remaining_ah==="number"){
-    return fmt(b.remaining_ah/Math.abs(b.current),1)+"h";
+function batteryTimeInfo(b){
+  if(!b.connected) return {label:"Runtime", value:"--"};
+
+  const current = b.current;
+  const remaining = b.remaining_ah;
+  const capacity = b.capacity_ah;
+
+  if(typeof current==="number" && current>.1 &&
+     typeof remaining==="number" && typeof capacity==="number" &&
+     capacity>remaining){
+    return {label:"Time to full", value:fmt((capacity-remaining)/current,1)+"h"};
   }
-  return "Idle";
+
+  if(typeof b.runtime_hours==="number" && b.runtime_hours>0){
+    return {label:"Runtime", value:fmt(b.runtime_hours,1)+"h"};
+  }
+
+  if(typeof current==="number" && current<-.1 && typeof remaining==="number"){
+    return {label:"Runtime", value:fmt(remaining/Math.abs(current),1)+"h"};
+  }
+
+  return {label:"Battery time", value:"Idle"};
 }
 function showTab(name){
   ["overview","battery","config"].forEach(t=>{
@@ -269,7 +284,9 @@ function render(data){
   $("socbar").style.width=Math.max(0,Math.min(100,b.soc||0))+"%";
   $("voltage").textContent=fmt(b.voltage,2)+" V";
   $("current").textContent=fmt(b.current,2)+" A";
-  $("runtime").textContent=runtimeText(b);
+  const timeInfo=batteryTimeInfo(b);
+  $("runtimeLabel").textContent=timeInfo.label;
+  $("runtime").textContent=timeInfo.value;
   $("bmsState").textContent=b.connected?"BMS Online":"BMS Offline";
   $("bmsState").className=b.connected?"medium good":"medium bad";
   $("battSource").textContent=b.source||"--";