This calculator estimates oven roasting time for beef, lamb, pork, chicken and turkey based on weight and how well done you want it, then shows the safe internal temperature to confirm with a thermometer. It is for home cooks planning a Sunday roast or holiday joint.
How it works
Times are based on standard guidelines at 180°C / 350°F: a per-500g rate for the chosen meat and doneness, plus a fixed base time. The total is:
time = (weight ÷ 500g) × minutes-per-500g + base
Per-500g rates are roughly 15 (rare), 20 (medium) and 25 (well) minutes for beef and lamb; 30–35 minutes for pork; and about 20 minutes for whole poultry. Base time is 15 minutes for joints and 20 for whole birds. Doneness also sets the target internal temperature.
Worked examples
Beef, medium (1.5 kg):
(1500 ÷ 500) × 20 + 15 = 3 × 20 + 15 = 75 minutes
Pull at 63°C / 145°F internal temperature, then rest 15 minutes.
Whole chicken (2 kg):
(2000 ÷ 500) × 20 + 20 = 4 × 20 + 20 = 100 minutes
Must reach 74°C / 165°F in the thickest part of the thigh (not touching bone).
Pork leg (1.8 kg):
(1800 ÷ 500) × 32 + 15 ≈ 3.6 × 32 + 15 ≈ 130 minutes
Safe at 63°C / 145°F; many cooks prefer 70°C for a firmer texture.
Internal temperature guide
A probe thermometer is more reliable than time alone. Every oven runs slightly differently, and bone, fridge-cold meat, or an unusually dense joint can all shift the actual cooking time.
| Meat | Doneness | Safe internal temp |
|---|---|---|
| Beef / lamb | Rare | 52–55°C / 125–131°F* |
| Beef / lamb | Medium | 63°C / 145°F |
| Beef / lamb | Well done | 71°C / 160°F |
| Pork | Any | 63°C / 145°F |
| Chicken | Any | 74°C / 165°F |
| Turkey | Any | 74°C / 165°F |
*Rare beef and lamb are personal-choice temperatures — the meat is safe in the center at this temperature but not at the food-safety standard. Poultry must always reach 74°C.
Resting and why it matters
Resting the meat after roasting is not optional for good results. Cutting straight from the oven lets the juices run out and the interior temperature continues rising for several minutes. A joint generally rests for 10–20 minutes under foil; a whole turkey benefits from 20–30 minutes. During the rest, the internal temperature typically rises 2–5°C, which is worth factoring in if you pull the meat just below the target.
Variables that shift the time
- Bone-in vs boneless — bone conducts heat differently; bone-in joints can take longer to reach temperature in the center
- Fridge-cold vs room-temperature meat — starting cold adds time; letting large joints sit at room temperature for 30 minutes before roasting helps even cooking
- Oven calibration — fan-assisted ovens cook faster than conventional; reduce the temperature by about 20°C (35°F) for fan ovens
- Joint shape — a compact, round joint retains heat and cooks more evenly than a long, thin one of the same weight
All estimates are calculated locally in your browser.