@@ -310,18 +310,22 @@ Eleven scenarios for manual verification of the Equipment Status Board's core us
 3. Verify the "Generate QR Code" button is enabled (not greyed out).
 4. Click the button to open `/equipment/<id>/qr`.
 5. Select each size preset in turn (1"–4" stickers, Avery 5160, Avery 5163, US Letter) and verify the live preview updates to match.
-6. Toggle the "Include equipment name" and "Include target URL" checkboxes and verify the preview updates accordingly.
-7. Download the label at the 2" sticker preset; open the PNG and verify it is 300 DPI.
-8. Print (or view at actual size) the downloaded label and scan it with a phone camera.
-9. Download the US Letter preset and verify the PNG is 2550×3300 px.
-10. Stop the server, unset `ESB_BASE_URL`, restart, and reload the equipment detail page.
-11. On an archived equipment item, confirm the QR button does not render and that `GET /equipment/<id>/qr` returns 404.
+6. Select each **Printer / device** preset in turn (Laser/Inkjet 300/600/1200 dpi, Thermal Label 203 dpi, Brother P-Touch 180 dpi) and verify the live preview updates.
+7. Toggle the "Include equipment name" and "Include target URL" checkboxes and verify the preview updates accordingly.
+8. For each device preset, download a label and confirm the PNG's pixel dimensions equal `int(size_inches × device_dpi + 0.5)` — e.g. a 4" sticker at Thermal Label (203 dpi) → 812×812 px; at Laser/Inkjet (1200 dpi) → 4800×4800 px.
+9. Confirm the PNG embeds matching DPI metadata. With ImageMagick: `identify -verbose file.png | grep Resolution`. Dependency-free: `python -c "from PIL import Image; print(Image.open('file.png').info['dpi'])"`. Note that a 203 dpi label reports approximately `(202.9968, 202.9968)` — this is expected rational rounding, not a bug.
+10. Confirm a 4" label at **Thermal Label (203 dpi)** prints full-size (no clipping) on a 203-dpi thermal printer, and that selecting **US Letter** at **Laser/Inkjet (1200 dpi)** shows a friendly "too large to render" error instead of downloading.
+11. Print (or view at actual size) a downloaded label and scan it with a phone camera.
+12. At the default Laser/Inkjet (300 dpi) device, download the US Letter preset and verify the PNG is 2550×3300 px.
+13. Stop the server, unset `ESB_BASE_URL`, restart, and reload the equipment detail page.
+14. On an archived equipment item, confirm the QR button does not render and that `GET /equipment/<id>/qr` returns 404.
 
 **Expected Results:**
 
-- The live preview on `/equipment/<id>/qr` reflects size and label-content options in real time.
+- The live preview on `/equipment/<id>/qr` reflects size, device, and label-content options in real time.
 - Scanning the downloaded/printed QR code resolves to `${ESB_BASE_URL}/public/equipment/<id>`.
-- Rendered PNG dimensions match the selected preset (e.g., letter → 2550×3300 px at 300 DPI).
+- Rendered PNG dimensions match the selected size × device DPI (e.g., at the default Laser/Inkjet 300 dpi device, US Letter → 2550×3300 px), and the PNG carries embedded DPI metadata matching the selected device.
+- US Letter at Laser/Inkjet (1200 dpi) is rejected with a friendly "too large" danger message rather than rendering.
 - When `ESB_BASE_URL` is unset, the "Generate QR Code" button renders as disabled with tooltip "ESB_BASE_URL not configured"; hitting the route directly redirects to the equipment detail page with a danger flash describing the validation failure.
 - Invalid `ESB_BASE_URL` values (non-http(s) schemes, embedded credentials, whitespace, paths/queries/fragments) are rejected with a specific flashed error instead of being rendered into the QR payload.
 - Archived equipment hides the QR button and the QR route returns 404.
@@ -142,14 +142,16 @@ Any logged-in user (Staff or Technician) can generate QR codes from the equipmen
 1. Open the equipment detail page for the item you want to label.
 2. Click **Generate QR Code**.
 3. Pick a size from the dropdown. Choices include square stickers (1", 1.5", 2", 3", 4"), Avery label sizes (5160 and 5163), and a US Letter full-page option.
-4. Optionally enable **Include equipment name above QR** to print the equipment's name at the top of the label.
-5. Optionally enable **Include URL below QR** to print the scan target URL at the bottom of the label.
-6. Watch the live preview update as you change options.
-7. Click **Download QR Code** to download a PNG file ready to print.
+4. Pick a **Printer / device** matching the printer you will print on: **Thermal Label (203 dpi)** for direct-thermal label printers, **Brother P-Touch (180 dpi)** for P-Touch label makers, or **Laser/Inkjet** at **300**, **600**, or **1200 dpi** for office printers. This setting makes the printed label come out at the correct physical size for the chosen printer. **Laser/Inkjet (300 dpi)** is the safe default for most office printers. (Very large sizes at very high resolution — e.g. US Letter at 1200 dpi — are rejected with a "too large" message; pick a lower resolution or smaller size.)
+5. Optionally choose a **WiFi Info** option to print a network reminder above the QR code: **None**, **Header** (a "Must be on WiFi" banner), **SSID** (banner + network name), or **Password** (banner + network name + password). Options only appear when an administrator has configured the corresponding WiFi settings.
+6. Optionally enable **Include equipment name above QR** to print the equipment's name at the top of the label.
+7. Optionally enable **Include URL below QR** to print the scan target URL at the bottom of the label.
+8. Watch the live preview update as you change options.
+9. Click **Download QR Code** to download a PNG file ready to print.
 
-All output is rendered at 300 DPI so labels print sharply at any of the listed sizes.
+Output is rendered at the selected device's resolution, with that DPI embedded in the PNG, so printing "actual size" reproduces the intended physical dimensions on that printer.
 
-> **Tip:** URL text below the QR is most useful at label/page sizes (Avery 5163, US Letter). On small stickers (≤ 2") the URL is usually truncated and adds little value — the live preview shows the result; uncheck **Include URL below QR** if it isn't legible.
+> **Tip:** URL text below the QR is most useful at label/page sizes (Avery 5163, US Letter). On small stickers (≤ 2") the URL is usually truncated and adds little value — the live preview shows the result; uncheck **Include URL below QR** if it isn't legible. On **low-resolution devices (180/203 dpi)**, the QR modules on tiny stickers (≤ 1") may be too small to scan reliably — prefer a larger sticker or a higher-resolution printer for tiny labels.
 
 ![QR Code Generation](images/qr-generation.png)
 
 
@@ -15,7 +15,7 @@
 from wtforms.validators import URL, DataRequired, Length, NumberRange, Optional
 
 from esb.models.document import DOCUMENT_CATEGORIES
-from esb.services.qr_service import QR_SIZE_PRESETS
+from esb.services.qr_service import DEFAULT_DEVICE_KEY, QR_DEVICE_PRESETS, QR_SIZE_PRESETS
 
 FORM_DOCUMENT_CATEGORIES = [('', '-- Select Category --')] + DOCUMENT_CATEGORIES
 
@@ -136,6 +136,12 @@ class QRGenerateForm(FlaskForm):
         validators=[DataRequired()],
         default='sticker_2',
     )
+    device = SelectField(
+        'Printer / device',
+        choices=[(p.key, p.label) for p in QR_DEVICE_PRESETS],
+        validators=[DataRequired()],
+        default=DEFAULT_DEVICE_KEY,
+    )
     wifi_info = SelectField('WiFi Info', default='none')
     include_name = BooleanField('Include equipment name above QR', default=False)
     include_url = BooleanField('Include URL below QR', default=False)
 
@@ -13,7 +13,6 @@
 from flask import current_app
 from PIL import Image, ImageDraw, ImageFont
 
-_DPI = 300
 _MIN_FONT_PT = 8
 
 
@@ -45,18 +44,41 @@ class QRSizePreset:
 QR_PRESETS_BY_KEY: dict[str, QRSizePreset] = {p.key: p for p in QR_SIZE_PRESETS}
 
 
-def _px(inches: float) -> int:
-    return int(inches * _DPI + 0.5)
+@dataclass(frozen=True)
+class QRDevicePreset:
+    key: str
+    label: str
+    dpi: int
+
+
+QR_DEVICE_PRESETS: tuple[QRDevicePreset, ...] = (
+    QRDevicePreset('laser_300', 'Laser/Inkjet (300 dpi)', 300),
+    QRDevicePreset('laser_600', 'Laser/Inkjet (600 dpi)', 600),
+    QRDevicePreset('laser_1200', 'Laser/Inkjet (1200 dpi)', 1200),
+    QRDevicePreset('thermal_203', 'Thermal Label (203 dpi)', 203),
+    QRDevicePreset('ptouch_180', 'Brother P-Touch (180 dpi)', 180),
+)
+QR_DEVICES_BY_KEY: dict[str, QRDevicePreset] = {p.key: p for p in QR_DEVICE_PRESETS}
+DEFAULT_DEVICE_KEY = 'laser_300'
 
+# High DPI × large physical size can produce enormous canvases (US Letter @ 1200 dpi
+# ≈ 134 MP). Cap total pixels to avoid OOM; this is a deliberate, adjustable default.
+MAX_CANVAS_PX = 50_000_000
 
-def _pt_to_px(pt: int) -> int:
-    return int(pt * _DPI / 72 + 0.5)
+
+def _px(inches: float, dpi: int) -> int:
+    return int(inches * dpi + 0.5)
+
+
+def _pt_to_px(pt: int, dpi: int) -> int:
+    return int(pt * dpi / 72 + 0.5)
 
 
 def render_qr_png(
     equipment,
     preset: QRSizePreset,
     *,
+    dpi: int = 300,
     include_name: bool = False,
     include_url: bool = False,
     base_url: str,
@@ -69,8 +91,16 @@ def render_qr_png(
     The service trusts `base_url` — it must be validated upstream via
     `esb.utils.text.get_normalized_base_url`.
     """
-    canvas_w_px = _px(preset.width_in)
-    canvas_h_px = _px(preset.height_in)
+    if dpi <= 0:
+        raise ValueError(f'dpi must be positive, got {dpi}.')
+    canvas_w_px = _px(preset.width_in, dpi)
+    canvas_h_px = _px(preset.height_in, dpi)
+
+    if canvas_w_px * canvas_h_px > MAX_CANVAS_PX:
+        raise ValueError(
+            f'{preset.label} at {dpi} dpi is too large to render — '
+            'choose a lower-resolution printer or a smaller size.'
+        )
 
     wifi_rows = _wifi_row_texts(wifi_info, wifi_ssid, wifi_password)
     num_wifi_rows = len(wifi_rows)
@@ -79,7 +109,7 @@ def render_qr_png(
     reserved_bottom = int(canvas_h_px * 0.15) if include_url else 0
 
     if num_wifi_rows > 0:
-        min_row_px = _pt_to_px(_MIN_FONT_PT) + 4
+        min_row_px = _pt_to_px(_MIN_FONT_PT, dpi) + 4
         wifi_budget = int(canvas_h_px * 0.30)
         max_text_px = int(canvas_h_px * 0.55)
         effective_wifi_rows = num_wifi_rows
@@ -155,30 +185,30 @@ def render_qr_png(
         if row_info['type'] == 'header':
             _draw_wifi_header_row(
                 canvas, row_top=row_top, row_height=wifi_row_height,
-                max_width_px=wifi_max_text_width,
+                max_width_px=wifi_max_text_width, dpi=dpi,
             )
         else:
             _draw_text_row(
                 canvas, row_info['text'],
                 row_top=row_top, row_height=wifi_row_height,
-                max_width_px=wifi_max_text_width,
+                max_width_px=wifi_max_text_width, dpi=dpi,
             )
 
     if include_name:
         _draw_text_row(
             canvas, equipment.name,
-            row_top=reserved_wifi, row_height=reserved_top, max_width_px=max_text_width,
+            row_top=reserved_wifi, row_height=reserved_top, max_width_px=max_text_width, dpi=dpi,
         )
     if include_url:
         _draw_text_row(
             canvas, qr_url,
             row_top=canvas_h_px - reserved_bottom,
             row_height=reserved_bottom,
-            max_width_px=max_text_width,
+            max_width_px=max_text_width, dpi=dpi,
         )
 
     buf = io.BytesIO()
-    canvas.save(buf, format='PNG')
+    canvas.save(buf, format='PNG', dpi=(dpi, dpi))
     return buf.getvalue()
 
 
@@ -200,7 +230,7 @@ def _wifi_row_texts(wifi_info, wifi_ssid, wifi_password):
     return rows
 
 
-def _draw_wifi_header_row(canvas, *, row_top, row_height, max_width_px):
+def _draw_wifi_header_row(canvas, *, row_top, row_height, max_width_px, dpi: int = 300):
     """Draw the WiFi emoji + 'Must be on WiFi' text centered in a row."""
     text_font_path = os.path.join(current_app.static_folder, 'fonts', 'DejaVuSans-Bold.ttf')  # noqa: PTH118
     emoji_font_path = os.path.join(current_app.static_folder, 'fonts', 'NotoEmoji-Bold.ttf')  # noqa: PTH118
@@ -210,13 +240,13 @@ def _draw_wifi_header_row(canvas, *, row_top, row_height, max_width_px):
             'QR WiFi emoji font missing at %s — falling back to text-only header.',
             emoji_font_path,
         )
-        _draw_text_row(canvas, label, row_top=row_top, row_height=row_height, max_width_px=max_width_px)
+        _draw_text_row(canvas, label, row_top=row_top, row_height=row_height, max_width_px=max_width_px, dpi=dpi)
         return
     gap = max(4, row_height // 10)
 
     text_font, rendered = _fit_text(
         label, max_width_px=int(max_width_px * 0.75),
-        max_height_px=row_height, font_path=text_font_path,
+        max_height_px=row_height, font_path=text_font_path, dpi=dpi,
     )
     if rendered == '':
         return
@@ -235,17 +265,17 @@ def _draw_wifi_header_row(canvas, *, row_top, row_height, max_width_px):
     text_h = t_bottom - t_top
 
     if emoji_w + gap >= max_width_px:
-        _draw_text_row(canvas, label, row_top=row_top, row_height=row_height, max_width_px=max_width_px)
+        _draw_text_row(canvas, label, row_top=row_top, row_height=row_height, max_width_px=max_width_px, dpi=dpi)
         return
 
     total_w = emoji_w + gap + text_w
     if total_w > max_width_px:
         text_font, rendered = _fit_text(
             label, max_width_px=max_width_px - emoji_w - gap,
-            max_height_px=row_height, font_path=text_font_path,
+            max_height_px=row_height, font_path=text_font_path, dpi=dpi,
         )
         if rendered == '':
-            _draw_text_row(canvas, label, row_top=row_top, row_height=row_height, max_width_px=max_width_px)
+            _draw_text_row(canvas, label, row_top=row_top, row_height=row_height, max_width_px=max_width_px, dpi=dpi)
             return
         t_left, t_top, t_right, t_bottom = draw.textbbox((0, 0), rendered, font=text_font)
         text_w = t_right - t_left
@@ -260,7 +290,7 @@ def _draw_wifi_header_row(canvas, *, row_top, row_height, max_width_px):
     draw.text((group_x + emoji_w + gap - t_left, text_y), rendered, fill='black', font=text_font)
 
 
-def _draw_text_row(canvas, text, *, row_top, row_height, max_width_px):
+def _draw_text_row(canvas, text, *, row_top, row_height, max_width_px, dpi: int = 300):
     """Draw centered text in a horizontal row region of the canvas."""
     font_path = os.path.join(current_app.static_folder, 'fonts', 'DejaVuSans-Bold.ttf')  # noqa: PTH118
     if not os.path.isfile(font_path):
@@ -273,6 +303,7 @@ def _draw_text_row(canvas, text, *, row_top, row_height, max_width_px):
         max_width_px=max_width_px,
         max_height_px=row_height,
         font_path=font_path,
+        dpi=dpi,
     )
     if rendered == '':
         return
@@ -285,14 +316,14 @@ def _draw_text_row(canvas, text, *, row_top, row_height, max_width_px):
     draw.text((x, y), rendered, fill='black', font=font)
 
 
-def _fit_text(text, *, max_width_px, max_height_px, font_path):
+def _fit_text(text, *, max_width_px, max_height_px, font_path, dpi: int = 300):
     """Return (font, rendered_text) fitting within max_width_px at ≤ max_height_px.
 
     Shrinks font toward the 8 pt floor; if still too wide at the floor,
     truncates with an ellipsis (binary-search); if even ellipsis alone
     doesn't fit, returns the min-size font and an empty string.
     """
-    min_px = _pt_to_px(_MIN_FONT_PT)
+    min_px = _pt_to_px(_MIN_FONT_PT, dpi)
     size_px = max_height_px
     step = max(1, int(max_height_px * 0.05))
     scratch = ImageDraw.Draw(Image.new('RGB', (1, 1)))
 
@@ -241,14 +241,27 @@ document.addEventListener('DOMContentLoaded', function () {
   var form = document.getElementById('qr-form');
   if (!form) return;
   var img = document.getElementById('qr-preview');
+  var errEl = document.getElementById('qr-preview-error');
   var base = form.getAttribute('data-preview-base');
   var timer = null;
+  // Attach once so they persist across every debounced img.src reassignment.
+  // A 400 (e.g. oversized canvas) degrades to a readable message, not a broken icon.
+  img.onerror = function () {
+    img.classList.add('d-none');
+    if (errEl) errEl.classList.remove('d-none');
+  };
+  img.onload = function () {
+    img.classList.remove('d-none');
+    if (errEl) errEl.classList.add('d-none');
+  };
   function update() {
     var size = form.querySelector('[name="size"]').value;
     var incName = form.querySelector('[name="include_name"]').checked ? '1' : '';
     var incUrl = form.querySelector('[name="include_url"]').checked ? '1' : '';
     var wifiInfo = form.querySelector('[name="wifi_info"]');
+    var device = form.querySelector('[name="device"]');
     var params = new URLSearchParams({ size: size });
+    if (device) params.set('device', device.value);
     if (wifiInfo) params.set('wifi_info', wifiInfo.value);
     if (incName) params.set('include_name', '1');
     if (incUrl) params.set('include_url', '1');
 
@@ -23,6 +23,10 @@ <h1>Generate QR Code &mdash; {{ equipment.name }}</h1>
                 <label for="{{ form.size.id }}" class="form-label">{{ form.size.label.text }}</label>
                 {{ form.size(class="form-select") }}
             </div>
+            <div class="mb-3">
+                <label for="{{ form.device.id }}" class="form-label">{{ form.device.label.text }}</label>
+                {{ form.device(class="form-select") }}
+            </div>
             <div class="mb-3">
                 <label for="{{ form.wifi_info.id }}" class="form-label">{{ form.wifi_info.label.text }}</label>
                 {{ form.wifi_info(class="form-select") }}
@@ -43,10 +47,11 @@ <h1>Generate QR Code &mdash; {{ equipment.name }}</h1>
         <h5>Preview</h5>
         <img id="qr-preview"
              alt="QR preview"
-             src="{{ url_for('equipment.qr_preview', id=equipment.id, size=form.size.data or 'sticker_2', include_name=form.include_name.data, include_url=form.include_url.data, wifi_info=form.wifi_info.data or 'none') }}"
+             src="{{ url_for('equipment.qr_preview', id=equipment.id, size=form.size.data or 'sticker_2', device=form.device.data or default_device_key, include_name=form.include_name.data, include_url=form.include_url.data, wifi_info=form.wifi_info.data or 'none') }}"
              class="img-fluid border"
              style="max-width: 400px;">
-        <p class="text-muted small mt-2">Preview is scaled to fit; downloaded PNG is at 300 DPI.</p>
+        <span id="qr-preview-error" role="alert" aria-live="assertive" class="text-danger small d-none">Preview unavailable for this combination — the label may be too large to render at this resolution, or the URL too long for this size. Try a lower resolution or a larger size.</span>
+        <p class="text-muted small mt-2">Preview is scaled to fit. The downloaded PNG is sized to your selected printer resolution and physical size.</p>
     </div>
 </div>
 {% endblock %}