Two halves of the same bird, two opposite jobs
The most useful thing to know about a duck leg is that it wants nothing to do with how you cook a duck breast. The breast is a lean, tender muscle that barely works, so it is cooked fast and served pink, right around 130 to 135°F, like a fine steak. The leg is the engine of the bird, a hard-working muscle packed with fat and connective tissue, and cooking it to a rosy medium-rare would give you something tough and chewy. The two cuts share a label and nothing else about technique.
What the leg wants is what dark meat always wants: low heat and time. The collagen that threads through a working muscle is rubbery until it is slowly coaxed into gelatin, and that transformation happens up around 175 to 195°F, held there for a while, far past the point that would ruin a breast. A duck leg taken to that range turns silky and tender and slips off the bone, basted from within by its own rendering fat. This is why confit, braising, and slow roasting are the duck-leg methods, and why searing it hot and fast like a breast is the fastest way to disappointment.
How long duck legs take, and why time is the real variable
The single most common question about duck legs is how long they take, and the honest answer is: longer than you expect, and the clock is a guide rather than a rule. Roasting at 375°F (191°C) runs about 85 to 100 minutes. Braising at 325°F (163°C), the legs partly submerged in stock or wine, takes roughly 2 hours. Confit, the legs fully submerged in fat at a very low 200°F (about 95°C), goes 4 hours or more. In every case you are not cooking to a moment, you are cooking to a condition: the meat should be tender enough that it pulls from the bone with no resistance, which lands somewhere around 185°F internal.
Because the window is so wide, duck legs are forgiving in a way that quick-cooked proteins are not. An extra fifteen minutes in a braise does no harm and often helps. What does harm the dish is impatience, pulling the legs while they are still short of that tender plateau, which leaves them safe to eat but tough. When in doubt, give them more time, not less.
Render the fat, save the fat, crisp the skin last
A duck leg comes with a thick cap of fat and skin, and handling it well is most of the craft. That fat is a feature: rendered slowly, it turns luscious and bastes the meat, and it drips off as one of the great cooking fats, worth straining and saving for the potatoes you will inevitably want to roast in it. Left unrendered, though, it stays flabby and unpleasant. So the move is to dry and salt the skin ahead, score the fat so it has an escape route, and give it sustained, gentle heat with the fat side exposed, pouring off the liquid fat as it collects rather than letting the leg stew in it.
Crisp skin and tender meat are on different clocks, and the trick is to serve the tenderizing first and the crisping last. Cook the legs low and long until the meat surrenders, then, at the very end, hit the skin with high heat, a blast in a hot oven or a quick press skin-side down in a screaming pan, to turn it crackling and golden. Confit is the purest expression of this idea: slow, submerged, impossibly tender, then crisped to order. The per-method guides below cover confit, braising, and roasting in detail.