How do I adjust cooking time for a larger roast?

As a general rule, cooking time scales with weight, but not perfectly linearly for very large cuts due to heat penetration physics. This calculator uses a proportional ratio: (New Weight / Original Weight) × Original Time. Always verify doneness with a meat thermometer.

Does cooking time double if I double the weight?

Roughly, yes, for cylindrical shapes like roasts. However, if you're cooking two separate 5lb chickens instead of one 10lb turkey, the time doesn't double—it stays similar to the single chicken time (maybe +10-15% for heat loss).

Should I rely solely on cooking time?

Never. Time is an estimate; temperature is a fact. Ovens vary, meat shapes vary, and starting temperatures vary. Use this calculator to plan your schedule, but use an instant-read thermometer to decide when dinner is ready.

What is carryover cooking?

Meat continues to cook after you remove it from the heat source. Large roasts can rise another 10-15°F (5-8°C) while resting. Remove your meat when it's slightly under your target temperature to prevent overcooking.

Home / Other / Cooking Timer

Cooking Time Calculator

Original Weight (kg)

New Weight (kg)

Original Cooking Time (minutes)

New Cooking Time

120 min

≈ 2h 0m

Reviewed by Sarah Jenkins, RD | Last Updated: November 2025

The Science of Cooking Times

Scaling recipes isn't just multiplication—it's physics. When you cook a larger piece of meat, heat has to travel further to reach the center. This calculator helps you estimate that time adjustment based on weight ratios.

💡 Expert Tip: The "Carryover" Factor

Meat doesn't stop cooking when you take it out of the oven. Residual heat can raise the internal temperature by 10-15°F (5-8°C) while it rests. Pull your roast early to avoid a dry dinner.

Common Mistakes

Trusting Time Over Temp: Time is a guess. Temperature is a fact. Always use a meat thermometer.
Opening the Oven: Every peek drops the temperature by 25-50°F, adding significant time to your cook.
Cooking Cold Meat: Let your roast sit at room temperature for 1 hour before cooking for more even results.

Frequently Asked Questions

How do I adjust for a convection oven?

Convection ovens cook faster. The general rule is to reduce the temperature by 25°F (15°C) or reduce the cooking time by about 25%.

Does this work for baking cakes?

Not exactly. Baking chemistry is more sensitive. If you double a cake recipe, you usually need to use two pans (same time) or a larger pan (lower temp, longer time). Use caution.

Why is my roast taking longer than calculated?

Factors include: starting meat temperature (was it frozen?), oven accuracy (most are off by 10-20°F), and pan material (glass vs metal).