A slow cook roast typically takes about 8 to 10 hours on low or 5 to 6 hours on high, with smaller roasts sometimes finishing a bit earlier and larger ones taking closer to the upper end of the range. For a boneless chuck roast around 3 pounds, common guidance is 8–10 hours on low or 5–6 hours on high, depending on your exact size and how tender you want it. Always check for fork-tork tenderness or an internal temperature around 145°F (63°C) for medium-rare to medium, or allow it to go higher if you prefer shreddable fall-apart texture. If you’re using a recipe with vegetables, you can add potatoes and carrots around the roast; many cooks add these in for the last 2–3 hours on low so they don’t overcook. Rest the meat for 10–20 minutes after cooking to redistribute juices before slicing or shredding. Tips to optimize results

• Sear the roast before slow cooking to develop flavor, then transfer to the slow cooker with onions, garlic, and your chosen liquid (broth, wine, or a combination).
• Ensure there’s enough liquid to cover at least halfway up the roast to prevent drying out.
• Use a thermometer: aim for an internal temperature of about 145°F (63°C) for slicing, or higher (150–170°F / 66–77°C) if you prefer shreddable texture.
• If your roast is thicker or shaped unevenly, plan for the longer end of the range and check for tenderness rather than a strict time.