Beef Roast Cooking Time Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/8/2026
Beef roast cooking time in a 220°C (425°F) oven is calculated with (weight ÷ 500g) × minutes per 500g: 12 min for rare, 15 min for medium, 20 min for well done. A 1.5 kg roast cooked medium takes about 45 minutes.
Explanation
This common rule of thumb for oven cooking time at 220°C (425°F) remains a starting estimate, not an absolute guarantee: actual time varies with the shape of the cut (a long, thin roast cooks faster than a compact piece of the same weight), its thickness, your oven's actual temperature (often different from the display setting), and the meat's temperature when it goes in (straight from the fridge or already at room temperature). This is why the truly reliable benchmark for checking doneness is never the timer alone, but the internal temperature measured with a probe thermometer — see our meat cooking temperature calculator, which gives the food-safety thresholds (63°C/145°F for a whole beef cut) never to go below, regardless of the doneness sought for taste. The time calculated here is therefore meant to plan the meal and know when to start checking the internal temperature, not to replace that check. After cooking, resting the meat outside the oven for several minutes, covered in foil, remains essential: it lets the juices redistribute through the cut and the internal temperature keep rising slightly, a point also covered in the food-safety thresholds page.
Example: a 1.5 kg roast cooked medium
Inputs
Weight: 1.5 kg. Doneness: medium (15 min/500g).
Calculation
Cooking time = (1.5 ÷ 0.5) × 15 = 3 × 15 = 45 minutes.
Result
This 1.5 kg roast needs about 45 minutes in a 220°C (425°F) oven for medium doneness — confirm with a probe thermometer before taking the meat out of the oven.
Frequently asked questions
Why does the shape of the roast affect cooking time at the same weight?
Because heat must travel from the surface to the center of the cut: a long, thin roast offers a shorter distance to the core than a compact, bunched-up piece of the same weight, so it cooks faster. This is why two roasts of identical weight but different shapes can need noticeably different cooking times despite this rule.
Should the roast be taken out of the fridge before cooking?
Letting the meat come to room temperature for about 30 minutes to 1 hour before cooking (depending on the size of the cut) allows more even cooking, with the surface and center starting closer in temperature. A roast put in straight from the fridge will generally need slightly longer than this rule estimates, which is calibrated for meat already at room temperature.
Does this rule also apply to pork, veal, or lamb?
Time-to-weight ratios differ by meat type and typical thickness: this calculator deliberately limits itself to beef roast, the most documented and commonly searched reference. For other meats, refer to type-specific benchmarks — but in every case, checking with a probe thermometer remains the universal reliable benchmark, regardless of the meat cooked. If the roast is coming out of the freezer, first check our thawing time calculator to plan the whole preparation.