Roast Chicken Cooking Time: Per Kg, 2kg & 180°C Guide

Few Sunday dinners spark as much debate in British kitchens as the humble roast chicken. The math seems simple — until you’re staring at a 2kg bird, wondering whether your oven runs hot and whether 90 minutes is enough. Most recipe writers hand you a timing table and walk away. This guide stays: UK grocers, recipe developers, and producers have tested their guidelines against real ovens, and the spread in their answers tells a story worth knowing.

Standard time per kg: 45 minutes + 20 minutes at 180°C (Waitrose) ·
RecipeTin Eats method: 10 min at 220°C + 20 min per 500g at 180°C ·
Manor Farm at 180°C fan: 45-65 minutes for 1.2-1.5kg chicken ·
BBC tool: Calculator for exact times ·
Internal temp target: 75°C/165°F

Three major calculation methods dominate UK roast chicken guidance, with their outputs varying by up to 28 minutes for the same 2kg bird.

How long do you roast a chicken per kg?

UK sources converge on a handful of formulas, but they don’t agree on which one is “right.” The most widely cited comes from Waitrose (UK supermarket guidance): 45 minutes per kilogram, plus 20 minutes extra. That puts a 1.5kg bird at roughly 87 minutes — about an hour and a half — at fan 180°C (gas mark 6). A 2kg chicken climbs to 110 minutes under the same rule.

A competing formula comes from RecipeTin Eats (recipe development blog), which skips the per-kg calculation in favour of a high-heat blast: 10 minutes at 220°C, then 20 minutes per 500g at 180°C until the internal temperature hits 75°C. This approach front-loads crisping and backs off when the bird is cooked through. For a 2kg chicken, that works out to approximately 85 minutes total — noticeably shorter than the Waitrose figure.

Manor Farm (chicken producer with UK distribution) offers a third calculation rooted in the traditional “per pound” rule: 20 minutes per 454g, plus an extra 20 minutes at 180°C fan. For a 2kg bird, this lands between 104 and 113 minutes — the longest estimate among major sources.

Times from Waitrose and BBC

BBC Good Food (UK public broadcaster food content) publishes variable guidance depending on bird size. A chicken of 1kg or under needs roughly 1 hour at 200°C (conventional) or 180°C fan, which aligns with the lower end of the per-kg formula. Larger birds — anything over 1.5kg — can push toward 1 hour 40 minutes at the same temperature. The BBC Good Food roast chicken recipe lists 1 hour 10 minutes for an approximately 1.8kg bird, positioning it in the middle of the range.

Adjustments for oven types

Fan ovens dominate UK kitchens, and the rule of thumb is simple: 200°C conventional = 180°C fan. If you’re using a conventional (static) oven, raise the dial by roughly 20°C to match the recipes designed for fan ovens. Tesco Real Food (UK retailer recipe platform) demonstrates this with a 1.5kg chicken cooked covered at fan 180°C for 45 minutes, then uncovered — a method that splits the difference between the two main approaches.

How long to cook a 2kg chicken?

A 2kg chicken sits at the most-searched weight in UK queries — and paradoxically, it’s where the timing formulas diverge most sharply. Under the Waitrose (UK supermarket guidance) rule of 45 min/kg + 20 min, a 2kg bird calls for exactly 110 minutes (1 hour 50 minutes). The RecipeTin Eats (recipe development blog) calculation — 10 minutes at 220°C, then 20 minutes per 500g at 180°C — yields roughly 85 minutes for the same weight. Manor Farm (chicken producer with UK distribution), applying its 20-min-per-454g rule, lands at 104–113 minutes.

The spread — from 85 to 113 minutes — isn’t evidence of error. It reflects real differences in oven calibration, bird density (a well-framed chicken cooks faster than a loosely stuffed one), and whether you start with a hot or cold oven. Manor Farm (chicken producer with UK distribution) explicitly advises weighing your bird after prep and any stuffing, since the weight used for calculation should reflect what goes into the oven, not the packaged figure on the label.

At 180°C

Fan 180°C is the consensus starting point across UK retailers and recipe developers. Waitrose (UK supermarket guidance) identifies this as gas mark 6 in fan terms. At this temperature, a 2kg bird falls in the 85–113 minute window depending on which formula you follow. Most sources converge toward 90–110 minutes as a practical working range.

At 200°C

Bumping the oven to 200°C conventional (equivalent to 180°C fan) shaves time but increases the risk of uneven browning and a drier breast. Jamie Oliver (UK chef and cookbook author) starts his roast chicken at 240°C for crisping, then drops to 200°C for the remaining cook — a method designed to rush the skin before the interior catches up. At 200°C fan, expect to subtract 10–15 minutes from the 180°C figures, but monitor more closely for doneness.

Free range specifics

Free range birds tend to be denser and leaner than intensively farmed equivalents, which can extend cooking time by 10–15 minutes per kilogram according to Manor Farm (chicken producer with UK distribution). The internal temperature target remains the same (75°C), but relying on time estimates alone with a free range bird introduces more risk. Weigh the prepared bird and adjust accordingly.

Do you cook chicken at 180 or 200?

Both temperatures appear across UK recipe guidance, and the choice depends on what you’re optimising for. Waitrose (UK supermarket guidance) and Tesco Real Food (UK retailer recipe platform) both anchor their primary guidance at fan 180°C (gas mark 6). Jamie Oliver (UK chef and cookbook author) reaches for 200°C+ when skin crispness is the priority. The honest answer: 180°C is the safer default; 200°C is a tool for specific outcomes.

Pros of 180°C

Lower-and-slower at 180°C fan produces more even cooking throughout the bird, from the thin breast tip to the dense thigh bone. The juices redistribute during a slower cook, and the skin — while not maximally crisp — still browns adequately without the risk of a burnt exterior and raw interior that comes from rushing with high heat. BBC Good Food (UK public broadcaster food content) recommends finishing at 220°C/200°C fan for 15–20 minutes if you want extra crispness without the all-over heat.

When to use 200°C

200°C (conventional, or 180°C fan equivalent) is appropriate when time is short and you’ve accepted the trade-off of more active monitoring. Jamie Oliver (UK chef and cookbook author) uses this approach intentionally, knowing that the higher initial heat drives the Maillard reaction faster on the skin surface while he drops the temperature partway through to avoid overcooking the breast. If you skip the temperature drop at 200°C, budget 15–20 minutes less time but check with a thermometer.

Oven type differences

Fan ovens move air, reducing the temperature needed for equivalent results. Conventional ovens retain hot air in static layers, meaning the bird’s top surface can brown faster while the lower portions lag. Tesco Real Food (UK retailer recipe platform) uses the 20°C offset as a standing conversion rule, and most UK retailers follow the same convention. If you’ve never calibrated your oven, a probe thermometer placed near the bird’s centre will tell you whether 180°C on your dial actually delivers 180°C at the roasting position.

Should I cover a chicken with foil when roasting?

The foil question divides recipe writers and home cooks alike. Tesco Real Food (UK retailer recipe platform) begins its 1.5kg roast chicken recipe with the bird covered for the initial 45 minutes, then uncovered for the remainder — a method designed to trap steam and keep the meat moist during the critical early phase. Jamie Oliver (UK chef and cookbook author) takes the opposite approach: no cover at any point, trusting the bird’s own fat and the oven’s dry heat to deliver both moisture and crispness simultaneously.

Foil for moisture

Covering a chicken loosely with foil for the first 30–45 minutes of roasting mimics the effect of a covered roasting tin or a slow braise: steam collects under the foil, warming the meat from all sides and preventing the surface from forming a crust prematurely. This is most useful when roasting at lower temperatures (170–180°C) or when working with a lean bird that won’t produce much self-basting fat. The risk is a steamed texture if left covered too long, which is why Tesco removes the foil partway through.

Uncovered for crispiness

Leaving the bird uncovered from the start allows the skin to dry slightly before cooking sets in, promoting the Maillard reaction that creates golden-brown colour and flavour compounds. RecipeTin Eats (recipe development blog) recommends patting the bird completely dry before roasting and leaving it uncovered throughout — the combination of surface moisture removal and full airflow produces the crispiest skin in test conditions. BBC Good Food (UK public broadcaster food content) endorses the uncovered method as the default, suggesting a brief high-temperature blast at the end for those who want extra crunch without the trade-off of full-on high-heat cooking.

How to roast chicken step by step

Timing formulas tell you when to stop. The step-by-step process tells you how to get there reliably. These stages draw from RecipeTin Eats (recipe development blog), Waitrose (UK supermarket guidance), and BBC Good Food (UK public broadcaster food content) to cover prep, oven setup, and doneness verification in sequence.

Prep and seasoning

Bring the chicken to room temperature at least 30 minutes before it goes in the oven — both RecipeTin Eats (recipe development blog) and Jamie Oliver (UK chef and cookbook author) agree on this point. A cold bird entering a hot oven cooks unevenly: the breast overcooks before the thigh reaches temperature. Pat the skin completely dry with kitchen paper — moisture is the enemy of crispness. Season generously under the skin as well as over it: salt applied to the flesh directly conducts flavour more effectively than salt scattered on top of fat.

Oven setup

Preheat to fan 180°C (or 200°C conventional) and position the rack in the centre. Waitrose (UK supermarket guidance) recommends basting with the bird’s own juices 2–3 times during cooking — do this quickly to minimise heat loss. If using the high-heat blast method, start at 220°C for 10–15 minutes before dropping to 180°C for the remainder of the cook time. Place the bird on a rack in a roasting tin to allow air circulation underneath. Om du vill steka rimmat fläsk i airfryer kan du följa den här guiden steka rimmat fläsk i airfryer.

Checking doneness

Time estimates are a starting point, not a guarantee. BBC Good Food (UK public broadcaster food content) specifies two reliable doneness checks: first, the juices running clear from the thickest part of the thigh — no pink tinge. Second, and more definitively, an internal temperature of 75°C or 70°C held for two minutes when measured at the thigh’s deepest point. RecipeTin Eats (recipe development blog) uses 75°C as its threshold. Rest the chicken covered for 15–20 minutes after removing from the oven — BBC Good Food (UK public broadcaster food content) recommends this as essential for juice redistribution, not optional.

The range across UK sources — from 85 minutes (RecipeTin) to 113 minutes (Manor Farm) for the same 2kg bird — tells you everything about why roast chicken inspires anxiety. No single formula is wrong; each reflects a different assumption about oven efficiency, bird density, and how much margin the cook prefers to carry. What the sources agree on without exception is the internal temperature threshold: 75°C, measured at the thigh’s deepest point, is the point beyond which food safety concerns disappear regardless of how you got there.