By Linda Garrould · Updated 7 August 2026
Roast beef is timed from doneness, not a flat clock: medium-rare wants 20 minutes per 500g, medium 25, medium-well 27.5, and well-done 30, in an oven at 180°C (160°C fan, gas mark 4) — so a 2kg topside cooked medium-rare takes around 1 hour 20 minutes. But there is a safety line running through all of this that most calculators skip over: a pink centre is only ever safe on a whole, intact joint that has not been rolled or tied. Topside is very often sold ready-rolled, and a rolled joint must be cooked all the way through, exactly like mince. Set the weight below, tell the timer whether your joint is rolled, and it will do the arithmetic — including working backwards from the time you want to sit down.
Rolled or tied joints are cooked through regardless of the doneness picked above — a rolled cut can carry bacteria on surfaces now sealed inside it, so it’s treated like mince: well-done, all the way through.
Cooked, safely: Beef is the one joint here where you choose the finish. A pink centre is only safe on an intact, non-rolled, non-mechanically-tenderised whole joint — contamination is assumed to sit on the surface only, and searing kills it there. At your chosen doneness, the centre should read about 55°C. Rolled or tied topside must be cooked through, like mince — use the “rolled or tied?” toggle below if that’s your joint.
Take the joint out of the fridge 30–60 minutes before roasting, pat it dry, and let a properly preheated oven do the rest. The timer below is your guide — the thermometer is the final word.
Roast beef cooking times by weight
The timer above and the chart below use exactly the same figures, so pin whichever you prefer to the fridge door. All times are per 500g and scale directly with weight — there is no flat addition, unlike lamb or pork. Times are for the main roast at 180°C conventional / 160°C fan / gas mark 4; joints over 1.5kg get a 20-minute sear first (see below), which replaces rather than adds to the first 20 minutes.
| Weight | Medium-rare | Medium | Medium-well | Well-done |
|---|---|---|---|---|
| 1 kg | 40 min | 50 min | 55 min | 1 hr |
| 1.5 kg | 1 hr | 1 hr 15 min | 1 hr 23 min | 1 hr 30 min |
| 2 kg | 1 hr 20 min | 1 hr 40 min | 1 hr 50 min | 2 hr |
| 2.5 kg | 1 hr 40 min | 2 hr 5 min | 2 hr 18 min | 2 hr 30 min |
| 3 kg | 2 hr | 2 hr 30 min | 2 hr 45 min | 3 hr |
Remember that medium-rare, medium and medium-well are only ever options on a whole, unrolled joint. If yours is rolled or tied — and a great many topside joints from the butcher’s counter are — use the well-done column regardless of how you’d otherwise like it served, and see the safety section below for why.
What the FSA and Waitrose actually recommend
Beef is the one joint on this site where you get to choose the finish, and that choice rests on a genuine food-safety distinction rather than personal taste alone. The Food Standards Agency’s guidance draws a clear line between whole cuts and joints that have been mechanically altered — minced, rolled, tied, tenderised or pierced — because bacteria on raw meat live on the surface, not inside the muscle. On an intact whole joint, searing the outside — browning every surface at high heat — kills anything sitting there, which is why the interior can safely stay pink. Once a joint is rolled, though, what was outside is now folded into the middle, and that surface bacteria goes with it. From that point on, the joint has to be treated like mince: cooked through, no exceptions.
Waitrose’s roasting guide gives the timings this page uses: 20 minutes per 500g for medium-rare, 25 for medium, 30 for well-done, all at 180°C (160°C fan, gas mark 4), with no flat addition on top — unlike a chicken or a lamb leg, the whole cooking time comes from that one multiplication. Waitrose names rare, medium and well-done as its three reference points; because rare has no separately sourced core-temperature figure from either source, this page and the timer above offer medium-rare, medium, medium-well and well-done as timed selections, with rare noted for reference only. Medium-well (27.5 minutes per 500g) is our own interpolation, sitting exactly halfway between the sourced medium and well-done figures.
For joints heavier than 1.5kg, both sources recommend starting with a short, fierce sear — 20 minutes at 240°C conventional (220°C fan, gas mark 9) — before dropping to the main roasting temperature. This is worth being precise about: the sear replaces the first 20 minutes of the roast, it does not extend the total time. A 2kg joint cooked medium-rare is still 1 hour 20 minutes overall, whether or not it gets the initial blast; the sear simply spends the first 20 of those minutes at a much higher heat, colouring the outside properly before the joint settles into its slower cook.
Rolled or whole: the distinction that changes everything
This is the section every other roast-beef calculator we looked at either buries in a footnote or leaves out entirely, and it deserves better than that treatment. It is not a minor caveat.
A pink or rare centre is safe to eat only on an intact, non-rolled, non-mechanically-tenderised whole cut. The reasoning is straightforward once it’s stated plainly: raw beef is presumed contaminated on its outer surface only, never in the muscle itself, because bacteria cannot travel through intact tissue on their own. Searing — visibly browning every outer face of the joint — deals with that surface contamination directly. Once the outside has been seared, the interior can be cooked to whatever doneness you like, because there was never anything to worry about in there.
Roll or tie that same joint, though, and the geometry changes. Topside in particular is very commonly sold ready-rolled and tied by the butcher, precisely because it is a lean, slightly awkward shape that holds together better that way. But rolling takes surface that was previously on the outside — and therefore exposed to whatever bacteria might be present — and tucks it into the centre of the joint. Tie a joint up and its middle is no longer guaranteed to be the sterile interior of an intact muscle; it may well be a fold of what used to be the outside. Searing the new exterior does nothing for meat that is now buried inside.
The practical upshot: a rolled or tied joint has to be cooked all the way through, like mince — well-done, checked at the centre, no pink allowed. This isn’t a style preference or a squeamish default; it’s the same logic that means a burger, made from meat that has been minced and had its entire outer surface folded through the middle, always has to be cooked through even though a steak from the same animal can be served rare. If you know your topside is rolled or tied — ask the butcher if the label doesn’t say — set the timer’s “rolled or tied?” toggle to yes and it will move you to the well-done figures automatically, regardless of which doneness you’d otherwise have picked.
Doneness and temperature: what “medium-rare” actually means
The clock gets you close; the thermometer settles it. Push a probe into the thickest part of the joint, away from any bone, and use these figures as your target:
| Doneness | Core temperature | Notes |
|---|---|---|
| Rare | 50°C | Reference only — no timed formula, so not offered as a choice |
| Medium-rare | ≈55°C | Interpolated/typical figure — Waitrose names rare, medium and well-done directly but does not publish a medium-rare temperature |
| Medium | 60°C | Waitrose-published |
| Medium-well | ≈65°C | Interpolated/typical figure — sits exactly halfway between the sourced medium (60°C) and well-done (70°C) temperatures |
| Well-done | 70°C | Waitrose-published; the only safe target for a rolled or tied joint |
Worth flagging plainly: the 55°C medium-rare and 65°C medium-well figures are our own interpolations — medium-rare sits between the sourced rare and medium temperatures, and medium-well sits between the sourced medium and well-done ones — because Waitrose’s guide names only rare, medium and well-done, without midpoints. Treat both as sensible typical figures rather than directly published ones. The 50°C, 60°C and 70°C figures either side of them are the ones we can point to a source for.
Resting: the science, not just the instruction
Every roast recipe tells you to rest the meat; fewer explain why, which is a shame because the reason is genuinely useful to understand rather than just obey. While a joint roasts, the heat drives moisture towards the centre and tightens the muscle fibres near the surface, squeezing them like a wrung-out cloth. Carve immediately and that trapped moisture runs straight out onto the board rather than staying in the meat — which is exactly what a dry, disappointing slice looks like.
Resting also finishes the cooking. This is called carryover cooking: the outer layers of the joint are hotter than the centre when it comes out of the oven, and that heat continues to migrate inward for some time afterwards even with no oven involved, nudging the core temperature up by several more degrees. A joint pulled at 55°C can easily read several degrees higher a quarter of an hour later, purely from residual heat working its way to the middle. This is why timings and temperatures should be read as “pull it here”, not “cook it to here” — overshoot the target in the oven and carryover will push you past it.
For beef, rest for 20 to 30 minutes, loosely tented with foil. Topside — the cut this page focuses on — is leaner and benefits from the longer end of that range, so 30 minutes is the default we’d point you towards. A more marbled cut like sirloin can get away with the shorter end if the oven is needed for something else, but topside rewards the patience.
Carving: against the grain, every time
One genuinely useful, slightly non-obvious tip: look closely at the joint before you carve and you’ll see the muscle fibres running in one direction, like the grain in a piece of wood. Slice with that grain — parallel to the fibres — and you get long, intact strands of muscle in every slice, which chew like elastic bands no matter how well the joint was cooked. Slice across the grain instead, at roughly a right angle to those fibres, and you’re cutting each strand into short lengths rather than leaving them whole, which is the difference between a tender slice and a stringy one. It costs nothing and takes no extra time — it simply means turning the joint, or your knife, ninety degrees from habit. Carve thinly, and carve it once the joint has finished resting, not before.
Tips for the best roast beef
- Bring it to room temperature first. Take the joint out of the fridge 30–60 minutes before it goes in. A joint that starts cold cooks less evenly, with more of a grey band beneath the surface before the centre catches up.
- Dry the surface before searing. Pat the joint thoroughly dry with kitchen paper. A dry surface sears and browns; a damp one steams, and a joint that steams instead of searing doesn’t get the surface treatment that makes a pink centre safe.
- Season generously, and don’t be shy with the pepper. Salt and a good crust of black pepper before it goes in do more for the finished flavour than anything added afterwards.
- Sit it on a trivet of vegetables. A bed of roughly chopped onion, carrot and celery lifts the joint off the base of the tin so hot air reaches the underside, and bastes itself in fat as it goes — the beginnings of a proper gravy, too.
- Use a thermometer, not just the clock. Ovens vary, joints vary in shape even at the same weight, and the timings above are a starting point. A probe thermometer removes the guesswork entirely, particularly if you’re aiming for a precise medium-rare.
- Rest it properly before carving. See above — 20 to 30 minutes, longer for topside, always tented loosely with foil rather than wrapped tightly.
Planning the whole Sunday lunch
Getting a joint of beef, the potatoes, the Yorkshire puddings and the gravy to arrive at the table together is the same logistical puzzle whichever roast you’re cooking, and it rewards working backwards from the moment you want to sit down rather than forwards from when things happen to go in. Use the “work backwards from lunch” box in the timer above and it will subtract the joint’s cooking time, its rest, and a margin for resting to give you a start time for the oven. Our stress-free Sunday lunch timing plan takes the whole meal apart course by course, in the same way our roast chicken timer does for a bird.
What to serve with roast beef
Roast beef earns the full treatment. Crisp roast potatoes — par-boiled, roughed up and finished in a hot oven — are non-negotiable, and a proper Yorkshire pudding, tall and crisp, is as much a beef tradition as a chicken one despite what the name might suggest. Add a sharp note of horseradish, a jug of gravy made from the resting juices and the trivet vegetables, and a green vegetable to cut through the richness. Allow roughly 200g of raw meat per person as a plain rule of thumb — a little more if the joint is on the bone, a little less if you know your table are light eaters.
More kitchen timers
If you found this useful, the rest of our one-tap kitchen timers take the guesswork out of the other joints and the trickiest small jobs: the roast chicken timer for a whole bird, the leg of lamb timer, the pork loin timer for crackling done properly, and the dippy egg timer and poached egg timer for breakfast.
Frequently asked questions
How long do I cook roast beef per kg?
By the numbers on this page, work in 500g units rather than whole kilograms: 20 minutes per 500g for medium-rare, 25 for medium, and 30 for well-done, at 180°C (160°C fan, gas mark 4). So a 2kg joint takes 1 hour 20 minutes medium-rare, 1 hour 40 medium, or 2 hours well-done. There’s no flat addition on top of that figure — it scales directly with weight.
What is the roast beef cooking time calculator formula?
Multiply the joint’s weight in 500g units by 20, 25 or 30 minutes depending on your chosen doneness (medium-rare, medium or well-done), with joints over 1.5kg getting an initial 20-minute sear at 240°C (220°C fan, gas 9) that replaces rather than adds to the first 20 minutes of that total. The timer above runs this same calculation for any weight and works backwards from your serving time too.
Can you eat roast beef pink in the middle?
Yes, but only if the joint is a whole, intact cut that hasn’t been rolled, tied or mechanically tenderised. Contamination on raw beef is assumed to sit on the outer surface only, and searing that surface kills it, which is why the centre of a whole joint can safely stay pink. A rolled or tied joint — very common with topside — must be cooked all the way through instead, exactly like mince, because rolling folds what was outside into the centre.
What temperature is medium-rare roast beef?
Around 55°C at the centre. This figure is our own interpolation between Waitrose’s published rare (50°C) and medium (60°C) temperatures, since medium-rare isn’t named directly in the source guidance — treat it as a sensible typical target rather than a precisely sourced one. Remember the joint will climb a few more degrees while it rests, so pull it a little short of your target.
Is there a doneness between medium and well-done?
Yes — medium-well, which this page adds as an interpolation: about 27.5 minutes per 500g and roughly 65°C at the centre, sitting exactly halfway between Waitrose’s published medium (25 minutes per 500g, 60°C) and well-done (30 minutes per 500g, 70°C) figures. It’s a sensible typical target rather than a directly published one, and it’s available as a selectable option on the timer above.
How long should I rest roast beef?
20 to 30 minutes, loosely tented with foil. Topside, being leaner, does better at the longer end of that range; a more marbled cut like sirloin can manage with less if you need the oven back sooner. Resting lets the juices redistribute through the meat and allows carryover cooking to finish the job, so the joint carves cleanly rather than bleeding out onto the board.
Do you sear beef before or after roasting?
Before, for joints over 1.5kg. Twenty minutes at a high 240°C (220°C fan, gas mark 9) browns the outside thoroughly, then the oven drops to the main roasting temperature of 180°C (160°C fan, gas 4) for the remainder. Importantly, that sear replaces the first 20 minutes of the total roasting time rather than adding to it — the overall time for a given weight and doneness stays the same either way.
How much roast beef per person?
A plain rule of thumb is around 200g of raw meat per person for a boneless joint, with a little more allowed if the joint is on the bone or your table has a healthy appetite. It’s a general guide rather than a beef-specific formula, so treat it as a starting point and adjust for who’s coming.
Is beef cooking time different in a fan oven?
The time is the same; you just lower the temperature. 180°C conventional and 160°C fan (gas mark 4) use the same per-500g figures for the main roast, and 240°C conventional and 220°C fan (gas mark 9) are equivalent for the initial sear on larger joints. The timer above has a Fan/Conventional/Gas toggle that handles the conversion for you.
Sources: Food Standards Agency — Cooking your food (the whole-cuts rule at §4.3 and the rolled-joint exception at §4.2); Waitrose — Roast Beef Cooking Times & Tips. This page is general cookery guidance, not a substitute for the instructions on your joint’s packaging or your butcher’s advice.