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What temperature should a refrigerator and freezer be?

By Roof & Router Team. Updated October 11, 2026.

What are the safe refrigerator and freezer temperatures?

Federal food safety guidance uses two numbers. The refrigerator should stay at 40°F or below. The freezer should be at 0°F.

Celsius values use °C = (°F − 32) × 5/9. For example, (40 − 32) × 5/9 = 4.4°C.

The FDA notes that bacteria that cause foodborne illness can double every 20 minutes at room temperature. Cold storage slows that growth. FoodSafety.gov says food stored continuously at 0°F or below stays safe indefinitely. Quality and taste can still decline over time.

Why ENERGY STAR suggests 35 to 38°F

Below 40°F is the safety line. ENERGY STAR recommends 35 to 38°F for the fresh-food section. That range keeps you under the limit even when the door opens often.

Going colder than needed costs money. The Department of Energy’s Building America Solution Center states that a fridge or freezer that is too cold uses excessive energy. For more on running costs, see how many watts a refrigerator uses.

Are the numbers on the fridge dial degrees?

Usually not. The FDA says few refrigerator controls show actual temperatures. A dial marked 1 to 5 or “colder/warmer” is a relative setting, not a reading.

The FDA recommends a freestanding appliance thermometer for each compartment. Check them often and adjust the setting if needed.

Where should I put the thermometer in the fridge?

The DOE Building America Solution Center gives a simple method:

1. Place the thermometer in a spacious area of the refrigerator.
2. Leave it for 5 to 8 hours without opening the doors often.
3. Read it, then adjust the control if the reading is off.
4. Put a second thermometer in the freezer, or repeat the test there later.

The same page notes some sources suggest setting the thermometer in a glass of water. That gives a steadier reading than air, which changes quickly when the door opens.

After you change the setting, give the fridge several hours to settle before you check again. This is a practical rule of thumb, not a federal figure.

Signs your fridge is too warm or too cold

The only reliable test is a thermometer. These signs suggest you should check one:

Possibly too warm

• The thermometer reads above 40°F.
• Milk and leftovers seem to spoil before their usual time.
• The freezer reads above 0°F, or ice cream turns soft.

Possibly too cold

• Lettuce, eggs, or drinks have ice in them. Water freezes at 32°F, so a fresh-food section that low is colder than it needs to be.
• The thermometer reads well below 35°F.

If the fridge seems to struggle, the DOE page notes that dirty condenser coils can make the compressor work harder. Unplug the unit before cleaning coils.

What to do in a power outage

FoodSafety.gov gives these hold times when the doors stay closed:

Keep the doors shut as much as possible. When power returns, check the thermometers before eating anything. The FDA says food in a fridge still at or below 40°F should be safe.

FoodSafety.gov’s chart says to discard raw or leftover cooked meat, poultry, and seafood exposed to 40°F or above for more than 2 hours. Frozen food can be refrozen if it still has ice crystals or is at 40°F or below. FoodSafety.gov’s rule: “When in doubt, throw it out.”

For backup power and planning, see winter power outage preparation. Never run a generator indoors or in a garage, because of carbon monoxide risk.

Quick answers

Is 40°F too warm for a refrigerator? 40°F is the upper safety limit. Aim a few degrees lower, at 35 to 38°F, so normal door openings don’t push it over.

What number should my fridge dial be on? There is no universal number, since most dials don’t show degrees. A middle setting is a common starting point; then adjust using an appliance thermometer.

Is 0°F cold enough for a freezer? Yes. Federal guidance says food kept continuously at 0°F or below stays safe indefinitely, though quality may decline.

Why is food freezing in my refrigerator? The fresh-food section is likely at or below 32°F. Check with a thermometer and turn the setting slightly warmer.

How long does a fridge stay cold without power? About 4 hours with the door closed, according to FoodSafety.gov. A full freezer holds about 48 hours.