Roast leg of lamb Cooking Time Calculator — Time, Temperature & Method

Roast leg of lamb Cooking Time Chart

Weight	Pink / rare	Medium	Well done
1 kg	1 hr	1 hr 15 min	1 hr 30 min
1.5 kg	1 hr 20 min	1 hr 40 min	2 hr
2 kg	1 hr 40 min	2 hr 5 min	2 hr 30 min
2.5 kg	2 hr	2 hr 30 min	3 hr
3 kg	2 hr 20 min	2 hr 55 min	3 hr 30 min

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How This Calculator Works — Formula & Method

Source: standard UK roasting guidance · applied deterministically · verify with a thermometer

Constant	Value	Source
Pink / rare — min per 500 g	20 min (range 15–20)	UK roasting guides
Pink / rare — internal temp	55°C / 131°F	FSA / thermometer
Medium — min per 500 g	25 min (range 20–25)	UK roasting guides
Medium — internal temp	60°C / 140°F	FSA / thermometer
Well done — min per 500 g	30 min (range 25–30)	UK roasting guides
Well done — internal temp	70°C / 158°F	FSA / thermometer
Base offset	25 min	Standard
Oven	220°C sear for 20 min, then 180°C	Method
Resting	15 min	Best practice

— Roast leg of lamb cooking time —
total_min = min_per_500g × (weight_g / 500) + base_offset
range = [lo_per_500g … hi_per_500g] × (weight_g / 500) + base_offset
conventional_oven = fan_temp + 10–20°C (same time)
fahrenheit = derived table from °C
— algorithm —
lookup(meat, cut, doneness) → point_estimate → guidance_range
→ internal_target_temp → verify_with_thermometer()

Public roasting guidance applied deterministically — this is not a food-safety authority. Always cook to the stated internal temperature, measured with a meat thermometer.