Butterflied leg of lamb Cooking Time Calculator

Butterflied leg of lamb Cooking Time Chart

Weight	Cooking time	Internal temp
1 kg	40 min	58°C
1.5 kg	55 min	58°C
2 kg	1 hr 10 min	58°C

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How This Calculator Works — Formula & Method

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

Constant	Value	Source
Time per kg	15 min per 500 g (range 12–20/500 g)	UK roasting guides
Internal target	58°C / 136°F	USDA / thermometer
Base offset	10 min	Standard
Oven	220°C sear for 20 min, then 200°C	Method
Resting	10 min	Best practice

— Butterflied leg of lamb cooking time —
total_min = min_per_500g × (weight_g / 500) + base_offset
range = [lo_per_500g … hi_per_500g] × (weight / 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.

Frequently Asked Questions

About 30 minutes per kg plus 10 minutes at 200°C fan, to 58°C internal. Boned and opened flat, it cooks much faster — great for the BBQ or a hot oven.

Cook at 200°C / 400°F. Internal target 58°C. Rest 10 minutes.