Roast Time Calculator Formula

Understand the math behind the roast time calculator. Each variable explained with a worked example.

Use the Roast Time Calculator

Formulas Used

Cooking Time

cook_time_min = weight_lbs * min_per_lb

Cooking Time

cook_time_hours = (weight_lbs * min_per_lb) / 60

Recommended Rest Time

rest_time = 15 + weight_lbs * 2

Total Time (cook + rest)

total_time = weight_lbs * min_per_lb + 15 + weight_lbs * 2

Variables

VariableDescriptionDefault
weight_lbsMeat Weight(lb)5
min_per_lbDoneness / Meat Type20

How It Works

How to Calculate Roast Time

Formula

Cooking Time = Weight (lb) x Minutes Per Pound

Minutes Per Pound Guidelines

  • Beef rare: 15 min/lb
  • Beef medium: 20 min/lb
  • Beef well done: 25 min/lb
  • Pork: 20 min/lb
  • Lamb: 25 min/lb
  • Chicken: 20 min/lb

    • Target Internal Temperatures

  • Beef rare: 125°F (52°C)
  • Beef medium: 145°F (63°C)
  • Pork: 145°F (63°C)
  • Chicken: 165°F (74°C)

    • Worked Example

    Calculate roasting time for a 5 lb beef roast to medium.

    weight_lbs = 5min_per_lb = 20
    1. 01Cooking time: 5 x 20 = 100 minutes.
    2. 02Rest time: 15 + 5 x 2 = 25 minutes.
    3. 03Total: 100 + 25 = 125 minutes (about 2 hours).
    4. 04Use a thermometer: target 145°F for medium.

    Ready to run the numbers?

    Open Roast Time Calculator