diff --git a/app/static/editor.js b/app/static/editor.js
index 48c94f4..05b6e0d 100644
--- a/app/static/editor.js
+++ b/app/static/editor.js
@@ -120,6 +120,27 @@ function wrapCanvasText(text, maxWidthPx) {
   return lines.length ? lines : [""];
 }
 
+function textNaturalWidthMm(obj) {
+  const { value } = objectFont(obj);
+  ctx.save();
+  ctx.font = value;
+  const lines = String(obj.text || " ").split("\n");
+  const maxTextWidthPx = Math.max(...lines.map((line) => ctx.measureText(line || " ").width), 0);
+  ctx.restore();
+  return Math.max(2, pxToMm(maxTextWidthPx) + 1);
+}
+
+function autoFitTextObject(obj) {
+  if (!state.design.autoLength || obj.manualSize || (obj.type !== "text" && obj.type !== "symbol")) return;
+  const maxLength = state.design.orientation === "portrait" ? state.design.tapeWidthMm : 500;
+  const available = Math.max(2, maxLength - obj.x - state.design.marginMm);
+  obj.w = Math.min(available, textNaturalWidthMm(obj));
+}
+
+function autoFitTextObjects() {
+  for (const obj of state.design.objects) autoFitTextObject(obj);
+}
+
 function objectContentEndMm(obj) {
   if (obj.hidden) return 0;
   if (state.design.orientation === "portrait") return obj.y + obj.h;
@@ -180,6 +201,7 @@ function syncDesignControls() {
   state.design.orientation = document.querySelector("input[name='orientation']:checked").value;
   controls.lengthMm.disabled = state.design.autoLength;
   if (state.design.autoLength) {
+    autoFitTextObjects();
     state.design.lengthMm = contentLengthMm();
     controls.lengthMm.value = state.design.lengthMm;
   }
@@ -361,6 +383,7 @@ function addObject(type, data = {}) {
     cols: 2,
     ...data,
   };
+  autoFitTextObject(base);
   state.design.objects.push(base);
   state.selectedId = base.id;
   draw();
@@ -401,11 +424,13 @@ function updateProps() {
 function applyProps() {
   const obj = selected();
   if (!obj) return;
+  const manuallySizing = document.activeElement === controls.propW || document.activeElement === controls.propH;
   obj.text = controls.propText.value;
   obj.x = Number(controls.propX.value);
   obj.y = Number(controls.propY.value);
   obj.w = Number(controls.propW.value);
   obj.h = Number(controls.propH.value);
+  if (manuallySizing) obj.manualSize = true;
   obj.fontSizeMm = Number(controls.propFont.value);
   obj.lineMm = Number(controls.propLine.value);
   obj.align = controls.propAlign.value;
@@ -413,6 +438,7 @@ function applyProps() {
   obj.fill = controls.propFill.checked;
   obj.rows = Number(controls.propRows.value);
   obj.cols = Number(controls.propCols.value);
+  autoFitTextObject(obj);
   draw();
 }
 
@@ -493,6 +519,7 @@ window.addEventListener("mousemove", (event) => {
   if (state.dragging.resize) {
     obj.w = Math.max(2, point.x - obj.x);
     obj.h = Math.max(2, point.y - obj.y);
+    obj.manualSize = true;
   } else {
     obj.x = Math.max(0, point.x - state.dragging.dx);
     obj.y = Math.max(0, point.y - state.dragging.dy);