How to adjust cooking times for different temperatures.

adjust cooking times for different temperatures

When I’m short on time, one of my favourite techniques is to crank up my oven so everything cooks quicker. Works every time! Here’s how to adjust cooking times for different temperatures.

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How to adjust cooking times for different temperatures.

STEP 1. Work out the percentage difference in temperature.

Start Temperature / End Temp = % Difference.

For example going from 400F (200C) to 450F (230C)
= 400 / 450 = 0.89 or 89%

STEP 2. Adjust Expected Time

Multiply initial time by the % Difference

Back to our example, if something takes 60 minutes at 400F (200C),
60 minutes x 0.89 = 53 minutes.

STEP 3. Add a safety margin

This isn’t an exact science, and you don’t want to burn dinner, so I check earlier just to be sure.

For our example if the new calculated time is 53 minutes, I’d check after 50 minutes.

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Video Tutorial
Convert Cooking Times for Different Temperatures.

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Common Examples of Different Temperatures – Fahrenheit

If starting time = 30 minutes

250F instead of 350F = 1.40 = 42 minutes
350F instead of 400F = 1.14 = 34 minutes
300F instead of 350F = 1.16 = 35 minutes
400F instead of 450F = 1.12 = 33 minutes

350F instead of 250F = 0.71 = 21 minutes
400F instead of 350F = 0.88 = 26 minutes
350F instead of 300F = 0.86 = 25 minutes
450F instead of 400F = 0.89 = 27 minutes

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Common Examples of Different Temperatures – Celsius

If starting time = 30 minutes

120C instead of 180C = 1.40 = 42 minutes
180C instead of 200C = 1.14 = 34 minutes
150C instead of 180C = 1.16 = 35 minutes
200C instead of 230C = 1.12 = 33 minutes

180C instead of 120C = 0.71 = 21 minutes
200C instead of 180C = 0.88 = 26 minutes
180C instead of 150C = 0.86 = 25 minutes
230C instead of 200C = 0.89 = 27 minutes

NOTE: There will be slight differences in your calculations for Celsius but the results won’t be significantly different.

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Other factors to consider when adjusting cooking times for different temperatures.

1. Opening the oven.

Every time you check and open the oven door, the temperature in the oven drops. Which will increase the cooking time.

This can result in you checking, opening, checking, opening and things ending up taking significantly longer than planned.

2. Space around the food

If you have equal amounts of say veggies for roasting and cram one sample into a small roasting dish but spread the other sample out on your largest rimmed baking sheet, there will be a significant difference in the time each takes to cook.

The more space, the easier it is for the heat to penetrate and the quicker the cooking time.

3. Shelf Height / Position in the Oven

Even in my fan assisted oven, things cook quicker on the top shelf than they will on the bottom.

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Oven Temperature Conversion Guide

(Oven Temperature Conversion Chart)

F = degrees Fahrenheit (degrees f)
C = degrees Celsius (degrees c)
GM = gas mark

200F = 100C – super slow cooking for meats etc. similar to a slow cooker.

300F = 150C = GM2 – regular slow roasting.

350F = 180C = GM4 – for most sweet baking, cookies, cakes etc. Roasting nuts.

400F = 200C = GM6 – Perfect roasting temperature for roasting veggies, roasting chicken, roast beef, roast lamb, cooking baked dishes, reheating food. Basically good for cooking everything else.

480F = 250C = GM9 – aka ‘cranking it’. For pizza, fast roast fish and times when I’m short on time.

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Can I cook something at a higher temp for a shorter time?

Absolutely! I do this all the time. The thing to watch out for is that you’re going to get quicker browning at a higher temperature. For small individual pieces of food like chicken thigh fillets or fish fillets or meatballs this isn’t a problem because the food will cook through.

BUT for a whole chicken, whole fish or large cut of meat you will need to be careful that you don’t get burnt on the outside and still raw in the middle. Generally for these larger cuts it’s better to stick to the lower temperature for the longer time. But sometimes I do start at the higher temperature for 10 or 15 minutes to speed up the cooking then reduce the temp back down.

For sweet treats and baked goods I generally stick to the recipe cooking temperature and time because it can be easy to burn the edges before the middle is cooked. But if I’m really rushed I will tweak the temperature slightly higher by no more than 50F / 20C / 1 Gas Mark.

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Can I bake something at a lower temperature for longer?

ABSOLUTELY! If you have more time cooking at lower temperatures can be great because you will get more even cooking.

Avoiding the burnt edges on your cake and the under baked middle (which sinks as it cools) is an excellent idea.

Lower temperatures are great because they give you a larger window of time between when your dish is cooked perfectly and when it gets over cooked.

For meat cooking lower slower cooking usually results in more tender succulent meat or poultry.

There is a time when lower temperatures do NOT help. For bread baking, pizza or anything where you’re looking to get significant rise in the oven (like a souffle) it’s better to stick to the recipe temperature because you need the heat to cause the air to expand or the steam to be created which gives a light springy texture.

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What happens if you bake at 350 instead of 400?

It’s just going to take a little longer. From our conversion chart above, 350F instead of 400F will take 1.14 more time. So something that takes 30 minutes at 400F will take 34 minutes at 350F.

Or for my fellow metric system users. Cooking at 180C instead of 200C will take 34 minutes instead of 30 minutes.

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How to cook 2 things in the oven at the same time at different temperatures

It’s simple. Use the oven set point for the most delicate item or for the one with the lowest temp. And expect the other item to take longer than normal.

Also put the more delicate / lower temp dish on the lower shelf as well.

For example. If I wanted to cook a cheesecake at 350F (180C) and a lasagna at 400F (200C). The cheeseckae would be the more ‘delicate’ dish because it will curdle if over baked. So I would set the oven to 350F (180C) put the cheesecake on the lower shelf and the lasagna on the top. Then when the cheesecake was cooked. IF the lasagna needed longer I’d increase the temperature to finish it more quickly.

For more on this see my Ultimate Oven Temperature Guide.

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More Cooking Skills

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Have fun in the kitchen!

With love,