diff --git a/src/App.jsx b/src/App.jsx
index 5ccf4fe..d3c118a 100644
--- a/src/App.jsx
+++ b/src/App.jsx
@@ -3,6 +3,7 @@ import AudioCapture from './components/AudioCapture'
 import ProgressionBanner from './components/ProgressionBanner'
 import ProgressionSuggestions from './components/ProgressionSuggestions'
 import Fretboard from './components/Fretboard'
+import BassFretboard from './components/BassFretboard'
 import Tuner from './components/Tuner'
 import Piano from './components/Piano'
 import Settings from './components/Settings'
@@ -42,7 +43,7 @@ export default function App() {
   const [isListening, setIsListening] = useState(false)
 
   // ── Instrument view + tuner ───────────────────────────────────────────────────
-  const [instrument, setInstrument] = useState('guitar')  // 'guitar' | 'piano'
+  const [instrument, setInstrument] = useState('guitar')  // 'guitar' | 'bass' | 'piano'
   const [showTuner, setShowTuner]   = useState(false)
   const [showDebug, setShowDebug]   = useState(false)
   const [monoColor, setMonoColor]   = useState(false)
@@ -394,6 +395,7 @@ export default function App() {
             className="appearance-none bg-surface border border-border hover:border-gray-500 focus:border-accent focus:outline-none rounded-lg pl-3 pr-7 py-1 text-sm text-gray-200 cursor-pointer transition-colors"
           >
             <option value="guitar">Guitar</option>
+            <option value="bass">Bass</option>
             <option value="piano">Piano</option>
           </select>
           <span className="pointer-events-none absolute right-2 top-1/2 -translate-y-1/2 text-gray-500 text-xs">▾</span>
@@ -517,10 +519,9 @@ export default function App() {
       {/* ── Instrument + progressions row ── */}
       <div className="flex gap-3 mb-3 items-stretch">
         <div className="w-full lg:w-[70%] min-w-0">
-          {instrument === 'guitar'
-            ? <Fretboard keyInfo={effectiveKey} currentChord={currentChord} pentatonicOnly={false} monoColor={monoColor} />
-            : <Piano keyInfo={effectiveKey} currentChord={currentChord} monoColor={monoColor} />
-          }
+          {instrument === 'guitar' && <Fretboard keyInfo={effectiveKey} currentChord={currentChord} pentatonicOnly={false} monoColor={monoColor} />}
+          {instrument === 'bass'   && <BassFretboard keyInfo={effectiveKey} currentChord={currentChord} monoColor={monoColor} />}
+          {instrument === 'piano'  && <Piano keyInfo={effectiveKey} currentChord={currentChord} monoColor={monoColor} />}
         </div>
 
         <div className="hidden lg:block w-[30%] min-w-0 relative">
diff --git a/src/components/BassFretboard.jsx b/src/components/BassFretboard.jsx
new file mode 100644
index 0000000..fa99e58
--- /dev/null
+++ b/src/components/BassFretboard.jsx
@@ -0,0 +1,149 @@
+import { getPentatonicScale, getFullScale, getChordTones, NOTES } from '../lib/theory'
+
+// Standard bass tuning (top of diagram = highest string)
+const STRINGS = [
+  { label: 'G', root: 7,  thickness: 1.5 },
+  { label: 'D', root: 2,  thickness: 2   },
+  { label: 'A', root: 9,  thickness: 2.5 },
+  { label: 'E', root: 4,  thickness: 3   },
+]
+
+const NUM_FRETS     = 13
+const FRET_MARKERS  = [3, 5, 7, 9]
+const DOUBLE_MARKER = 12
+
+// Layout
+const NUT_X    = 40
+const OPEN_X   = 18
+const FRET_W   = 52
+const STRING_H = 36   // wider spacing than guitar — 4 strings feel more spread
+const PAD_T    = 28
+const PAD_B    = 18
+const BOARD_W  = NUT_X + (NUM_FRETS - 1) * FRET_W + 10
+const BOARD_H  = PAD_T + 3 * STRING_H + PAD_B
+const DOT_R    = 10
+
+const fretX   = f  => NUT_X + (f - 0.5) * FRET_W
+const stringY = si => PAD_T + si * STRING_H
+
+function noteColor(isChordTone, isPenta, isScale, mono = false) {
+  if (isChordTone) return { fill: '#a855f7', text: '#fff' }
+  if (isPenta)     return mono ? { fill: '#c084fc', text: '#1e1b4b' } : { fill: '#f59e0b', text: '#000' }
+  if (isScale)     return mono ? { fill: '#e9d5ff', text: '#581c87' } : { fill: '#374151', text: '#d1d5db' }
+  return null
+}
+
+export default function BassFretboard({ keyInfo, currentChord, monoColor = false }) {
+  const { root, mode } = keyInfo ?? {}
+
+  if (!root) return null
+
+  const pentaSet = new Set(getPentatonicScale(root, mode).map(n => NOTES.indexOf(n)))
+  const scaleSet = new Set(getFullScale(root, mode).map(n => NOTES.indexOf(n)))
+  const chordSet = currentChord
+    ? new Set(getChordTones(currentChord).map(n => NOTES.indexOf(n)))
+    : new Set()
+
+  return (
+    <div className="bg-panel border border-border rounded-2xl p-6">
+      <p className="text-sm text-gray-500 uppercase tracking-widest mb-4">
+        Bass — {root} {mode}
+        {currentChord && <span className="text-amber-400 ml-2">/ {currentChord}</span>}
+      </p>
+
+      <div>
+        <svg
+          viewBox={`0 0 ${BOARD_W} ${BOARD_H}`}
+          width="100%"
+          height="auto"
+          style={{ display: 'block' }}
+        >
+          {/* Fretboard background */}
+          <rect x={NUT_X} y={PAD_T - 6} width={BOARD_W - NUT_X - 4} height={3 * STRING_H + 12}
+            fill="#1a120b" rx={2} />
+
+          {/* Position marker dots (centred between strings 1–2) */}
+          {FRET_MARKERS.map(f => (
+            <circle key={f}
+              cx={fretX(f)} cy={PAD_T + 1.5 * STRING_H}
+              r={5} fill="#3a2a1a" />
+          ))}
+          {/* Double dot at 12 */}
+          <circle cx={fretX(DOUBLE_MARKER)} cy={PAD_T + 0.5 * STRING_H} r={5} fill="#3a2a1a" />
+          <circle cx={fretX(DOUBLE_MARKER)} cy={PAD_T + 2.5 * STRING_H} r={5} fill="#3a2a1a" />
+
+          {/* Fret lines */}
+          {Array.from({ length: NUM_FRETS - 1 }, (_, i) => i + 1).map(f => (
+            <line key={f}
+              x1={NUT_X + f * FRET_W} y1={PAD_T - 6}
+              x2={NUT_X + f * FRET_W} y2={PAD_T + 3 * STRING_H + 6}
+              stroke={f === DOUBLE_MARKER ? '#888' : '#4a3a2a'}
+              strokeWidth={f === DOUBLE_MARKER ? 2 : 1} />
+          ))}
+
+          {/* Nut */}
+          <line x1={NUT_X} y1={PAD_T - 6} x2={NUT_X} y2={PAD_T + 3 * STRING_H + 6}
+            stroke="#c0b090" strokeWidth={4} />
+
+          {/* Strings — thicker as pitch drops */}
+          {STRINGS.map((s, si) => (
+            <line key={si}
+              x1={OPEN_X - DOT_R - 2} y1={stringY(si)}
+              x2={BOARD_W - 8}        y2={stringY(si)}
+              stroke="#9ca3af"
+              strokeWidth={s.thickness} />
+          ))}
+
+          {/* Fret numbers */}
+          {[3, 5, 7, 9, 12].map(f => (
+            <text key={f}
+              x={fretX(f)} y={PAD_T - 10}
+              textAnchor="middle" fontSize={10} fill="#6b7280"
+            >{f}</text>
+          ))}
+
+          {/* String labels */}
+          {STRINGS.map((s, si) => (
+            <text key={si}
+              x={6} y={stringY(si) + 4}
+              textAnchor="middle" fontSize={10} fill="#6b7280"
+            >{s.label}</text>
+          ))}
+
+          {/* Note dots */}
+          {STRINGS.flatMap((str, si) =>
+            Array.from({ length: NUM_FRETS }, (_, fi) => {
+              const pc    = (str.root + fi) % 12
+              const color = noteColor(chordSet.has(pc), pentaSet.has(pc), scaleSet.has(pc), monoColor)
+              if (!color) return null
+
+              const cx = fi === 0 ? OPEN_X : fretX(fi)
+              const cy = stringY(si)
+
+              return (
+                <g key={`${si}-${fi}`}>
+                  <circle cx={cx} cy={cy} r={DOT_R} fill={color.fill} />
+                  <text
+                    x={cx} y={cy + 4}
+                    textAnchor="middle"
+                    fontSize={9}
+                    fontWeight="600"
+                    fill={color.text}
+                  >
+                    {NOTES[pc]}
+                  </text>
+                </g>
+              )
+            })
+          )}
+        </svg>
+      </div>
+
+      <div className="mt-3 flex gap-5 text-xs text-gray-500">
+        <span><span className="text-accent">●</span> Chord tone</span>
+        <span style={{ color: monoColor ? '#c084fc' : '#f59e0b' }}>●</span><span> Pentatonic</span>
+        <span style={{ color: monoColor ? '#e9d5ff' : '#6b7280' }}>●</span><span> Scale</span>
+      </div>
+    </div>
+  )
+}