How Long to Cook Half a Salmon in the Oven

A half side of salmon takes about 20–24 minutes in a 400°F (200°C) oven, with the exact time depending on its thickness. This simple lemon-and-dill version is roasted skin-side down and checked with a thermometer so the center reaches the USDA safe minimum temperature without relying on timing alone.

Ingredients

1 half side of salmon, skin on, about 2¼ lb (1 kg), ideally 1–1½ inches (2.5–4 cm) thick at its thickest point
1 tablespoon (15 ml) olive oil
1 teaspoon (6 g) fine sea salt
½ teaspoon (1 g) freshly ground black pepper
1 medium lemon, finely grated zest plus 2 tablespoons (30 ml) juice; reserve extra wedges for serving if desired
2 garlic cloves, finely grated or minced, about 2 teaspoons (6 g)
2 tablespoons (6 g) chopped fresh dill, plus a little extra for serving
1 teaspoon (5 g) Dijon mustard

Instructions

Heat the oven and prepare the pan. Arrange a rack in the center of the oven and heat it to 400°F (200°C). Line a rimmed baking sheet with parchment paper or foil. A rimmed pan catches the juices; parchment makes cleanup easy. If the salmon is longer than the pan, ask the fish counter to cut it to fit, or fold the thinner tail end underneath so it cooks more evenly.
Check and dry the salmon. Keep the fish refrigerated until you are ready to prepare it. Run clean fingers over the flesh to find any pin bones and pull them out with clean tweezers. Pat the salmon dry with paper towels, especially on the flesh side. Drying the surface helps the seasoning cling and keeps the fish from steaming in a layer of moisture.
Season the fish. Set the salmon skin-side down on the prepared pan. In a small bowl, mix the olive oil, salt, pepper, lemon zest, lemon juice, garlic, dill, and Dijon. Brush or spoon the mixture over the flesh, spreading it to the edges. The Dijon is a small amount, so it will not make the salmon taste strongly of mustard; it helps the lemon and oil coat the surface. Let the fish sit only while the oven finishes heating, rather than leaving it out for an extended time.
Roast until nearly done. Bake the salmon uncovered for about 20–24 minutes. Begin checking at 20 minutes because thinner sides and narrow tail sections cook faster. The surface should look opaque around the edges, while the center may still look slightly translucent before it is fully cooked. Avoid judging doneness by color alone: salmon can remain darker in the center even when it is safe, and a thick piece can look pale on the outside before its middle is ready.
Check the temperature at the thickest point. Insert an instant-read food thermometer sideways into the center of the thickest part, taking care not to touch the pan. USDA FSIS lists 145°F (63°C) as the safe minimum internal temperature for fish; cook until the thermometer reads at least that temperature. If it has not reached 145°F (63°C), return the pan to the oven and check again after 2 minutes. Repeat as needed, since thickness and oven performance vary. Do not use the temperature from the thin tail as a substitute for checking the thick center.
Rest and serve. Once it reaches 145°F (63°C), take the pan out and leave the salmon to rest for 5 minutes. The flesh will firm slightly and be easier to portion. Slide a wide spatula between the skin and flesh if you want to lift off portions without the skin; otherwise, serve from the pan and let guests leave the skin behind. Spoon any pan juices over the fish before serving.

Tips

Let thickness guide the clock. The 20–24 minute estimate is for a half side around 1–1½ inches (2.5–4 cm) thick at its thickest point. A thinner fillet may be ready sooner, while a particularly thick center can take longer. If your piece tapers dramatically, fold the tail underneath or cover just that thin section loosely with foil once it is cooked through.
Choose the right fish. A skin-on side is easy to roast because the skin helps protect the flesh from the hot pan. Fresh or fully thawed frozen salmon both work. Thaw frozen fish overnight in the refrigerator, then pat it dry; do not roast it while partly frozen, as the exterior can overcook before the center reaches a safe temperature.
Swap herbs and citrus to suit what you have. Chopped parsley or chives can replace the dill in the same amount. If you do not have a fresh lemon, use 1 tablespoon (15 ml) bottled lemon juice and omit the zest; the flavor will be less fragrant but still bright. Lime juice also works, though it gives the fish a sharper, different citrus note.
Season gently if serving a crowd. The salt amount is intended for the full 2¼ lb (1 kg) side. If the salmon is substantially smaller, reduce salt and oil proportionally. If your Dijon or seasoning blend is already salty, start with less salt, then let people add more at the table. Use a clean plate and utensils for the cooked fish rather than reusing anything that touched raw salmon.

Serving Suggestions

Serve the salmon warm with the roasted lemon and dill juices spooned over the top. For a straightforward dinner, pair it with boiled or roasted potatoes and a green vegetable such as asparagus, green beans, or broccoli. Rice, couscous, or crusty bread also works well for catching the lemony oil from the pan. Add a crisp salad with a mild vinaigrette if the rest of the meal is rich.

For a larger table, bring the whole side to the table on its baking sheet or transfer it carefully to a long platter. Cut portions across the width of the fish, following the natural flakes, and offer lemon wedges, extra chopped dill, and a small bowl of sauce on the side. A quick sauce of plain yogurt, chopped herbs, lemon juice, and a pinch of salt is a useful cool contrast; keep it separate so diners can choose how much they want.

Variations

Maple-mustard salmon: Replace the olive oil and Dijon mixture with 1 tablespoon (15 ml) olive oil, 1 tablespoon (15 ml) pure maple syrup, and 1 tablespoon (15 g) Dijon mustard. Add the lemon zest and a little pepper, but use only 1 tablespoon (15 ml) lemon juice. The glaze will be sweeter and brown more quickly, so begin checking early and loosely shield any darkening edges with foil. The safe temperature remains the same.

Garlic and parsley: Use 2 tablespoons (8 g) chopped parsley instead of dill and add ½ teaspoon (1 g) smoked paprika if you like a warm, savory note. This version pairs especially well with potatoes or rice. Spicy citrus: Add ¼ teaspoon (0.5 g) red pepper flakes and use orange zest alongside the lemon zest. Orange makes the flavor rounder and sweeter; keep the lemon juice for enough acidity to balance it.

Foil packet option: For easier cleanup and a softer, more gently steamed texture, set the seasoned fish on a large sheet of foil and fold the edges into a loose packet, leaving room above the fish. Roast at the same temperature and start checking around 20 minutes. A sealed packet holds in moisture, so the surface will not brown as much as uncovered salmon. Open the packet carefully, since hot steam escapes, and use the thermometer at the thickest point.

Storage and Reheating

Refrigerate leftover salmon within 2 hours of cooking, sooner if the room is very warm. Remove the flesh from the skin if that makes it easier to store, then place it in a shallow airtight container. Cooked salmon keeps for 3–4 days in the refrigerator. For longer storage, freeze it in a well-sealed freezer container; it is best used within about 2–3 months for quality. Thaw frozen leftovers in the refrigerator rather than on the counter.

To reheat, place a portion in a small oven-safe dish with a teaspoon of water or broth and cover it loosely. Warm it in a 275°F (135°C) oven until a food thermometer reads 165°F (74°C), the safe temperature for reheated leftovers. The time varies with portion size, so use temperature rather than a fixed minute count. A microwave also works: cover the fish and heat it in short intervals, checking the center with a thermometer. Reheating can dry salmon, so stop as soon as it reaches 165°F (74°C). Flaked cold leftovers can also be served in a salad or sandwich without reheating, provided they have been stored safely.

Frequently Asked Questions

How long does a half salmon take at 400°F?
A half side about 1–1½ inches (2.5–4 cm) thick usually takes 20–24 minutes at 400°F (200°C). Start checking at 20 minutes and use a thermometer at the thickest point. A wide, thick side may take longer, while a thinner or smaller one can finish sooner.

Should I bake half a salmon covered or uncovered?
For lightly roasted edges and a surface that is not too moist, bake it uncovered on a lined rimmed pan. Covering it loosely with foil can help if the top is browning faster than the center cooks, but a tightly sealed foil packet traps steam and produces a softer, less browned finish.

Do I bake salmon skin-side up or down?
Place it skin-side down for this method. The skin acts as a buffer between the flesh and the hot pan, and the cooked fish is easy to lift away from it when serving. You do not need to flip a large side during roasting.

How can I tell when a whole half side is cooked?
Check the thickest section with an instant-read thermometer; it should reach 145°F (63°C), the USDA FSIS safe minimum for fish. Look for flesh that separates into flakes with gentle pressure, but treat appearance as a secondary cue because color and flaking differ by salmon variety and thickness.

Can I roast a half side of salmon from frozen?
For the most even result, thaw it in the refrigerator first and pat the surface dry. A frozen half side has uneven thickness and releases water as it cooks, making timing harder to predict. If you must cook it from frozen, follow the package directions when available, allow substantially more time, and rely on a thermometer to confirm 145°F (63°C) throughout the thickest area.

Can I prepare it ahead?
You can mix the oil, herbs, lemon, and mustard a few hours ahead and refrigerate the mixture separately. Keep the salmon covered in the refrigerator, then season it shortly before baking. Avoid adding lemon juice far in advance, since the acidity can change the surface texture of the fish. Bake close to serving time for the best texture.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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