A dial marked 1 to 7 with no units on it is one of the more unhelpful pieces of appliance design still in common use. Half of people assume 1 is coldest because it sounds like a first setting, and the other half assume the numbers are temperatures.
Neither is right, and the consequence of guessing wrong is either food that isn't properly frozen or a compressor running far harder than it needs to.
The Short Answer
Higher numbers mean colder. On virtually every freezer sold in the UK, 1 is the warmest setting and the highest number — 5, 7 or 9 depending on the model — is the coldest.
They are not temperatures. They're a relative scale controlling how long the compressor runs before the thermostat is satisfied. Setting 4 does not mean 4°C, and there's no fixed conversion.
The middle is usually right. On a 1-7 dial, 3 or 4 gets most freezers to around -18°C, which is the correct target. On a 1-5 dial, 3.
The only way to know is a thermometer. A freezer thermometer costs a few pounds. Put it in the middle of the load, leave it 24 hours, and read it. That single measurement tells you more than any amount of dial-turning.
What you're aiming for: -18°C in a freezer, and 3-5°C in a fridge.
What Actually Matters
The dial controls run time, not temperature directly. The thermostat is a switch that turns the compressor on when the cabinet warms past a threshold and off when it cools below one. The dial moves those thresholds. A higher number means the compressor keeps running until it's colder inside.
The same setting gives different temperatures in different conditions. A freezer on setting 4 in a cool utility room will run colder than the same freezer on setting 4 in a warm kitchen or a hot garage, because the compressor is fighting a different heat load. This is why there's no universal answer and why measuring beats guessing.
-18°C is a real number, not a convention. It's the internationally agreed storage temperature at which the deterioration of frozen food effectively stops for practical purposes. Above it, food remains safe but quality declines noticeably faster — ice crystals grow, texture suffers, and stated storage times no longer apply.
Detailed Analysis
Why manufacturers use numbers at all
Two reasons, one defensible and one less so.
The defensible one is that a mechanical thermostat genuinely can't be calibrated to a temperature. It's a bellows or a bimetallic device responding to a sensor, and the actual cabinet temperature it produces depends on the room temperature, how full the appliance is, and how often the door opens. Printing "-18°C" on a dial position would be a promise the appliance can't keep.
The less defensible one is cost. Digital displays with actual temperature readouts exist on more expensive models, and the numbered dial persists at the budget end because it's a cheap component.
The practical upshot is that the numbers are ordinal — they tell you the direction, not the destination. Which is fine, provided you know which direction is which.
Working out what your setting is doing
The method takes 24 hours and one cheap thermometer.
Buy a freezer thermometer — the small dial or digital type designed to sit inside. Put it in the middle of the load rather than on the door or against a wall, because that's where the food is and the edges aren't representative.
Leave it a full 24 hours. Freezers cycle, and a reading taken twenty minutes after you've had the door open tells you nothing. A full day covers several compressor cycles and a normal pattern of door openings.
Then read it. If it's around -18°C, leave the dial alone. If it's warmer than -15°C, go up one setting and repeat. If it's below about -22°C, you can come down a setting and save some electricity.
Change one setting at a time and wait a full day between adjustments. The cabinet takes hours to stabilise and adjusting repeatedly just produces confusion.
Adjusting for the seasons and the room
This is where the relative nature of the scale becomes useful rather than annoying.
In a garage or an unheated utility room, the room temperature swings substantially through the year. In a hot summer the compressor has more work to do and the same dial setting produces a warmer cabinet. In deep winter the opposite applies.
So a freezer in an unstable environment genuinely benefits from a seasonal adjustment — up a setting in July, back down in November. A freezer in a heated kitchen at a steady 20°C doesn't need this at all.
How full the appliance is also matters. A full freezer holds its temperature better because frozen food is thermal mass, so the compressor cycles less. A nearly empty freezer swings more with every door opening. If you've just emptied a chest freezer for defrosting and refilled it lightly, expect it to run more for a while.
Fridge dials, which work the same way
Fridge-freezers with separate controls have the same convention on both: higher is colder.
The fridge target is 3-5°C, and the same measurement approach applies — a thermometer in the middle of the middle shelf, left for a day.
One complication on many fridge-freezers: a single thermostat controls both compartments, with a damper directing cold air. On those, turning the dial affects both, and getting the freezer right can leave the fridge too cold or vice versa. It's a known limitation of the design rather than a fault, and it's why models with independent controls cost more.
The related problem is a fridge-freezer in a cold room, where the fridge stops calling for cooling because the room is already cool — and because the compressor serves both, the freezer stops getting cold too. That's a placement issue rather than a dial issue and no setting fixes it.
Real-World Considerations
Turning the dial to maximum "to be safe" is the common instinct and it's counterproductive. It runs the compressor far more than necessary, adds meaningfully to the electricity bill, and doesn't make the food any safer once you're past -18°C. In a fridge it also risks freezing the items at the back.
New appliances need time. A freezer switched on for the first time takes several hours to reach temperature empty, and considerably longer once loaded. Don't judge the setting on the first day, and don't fill it with a large quantity of unfrozen food immediately.
The fast freeze or super freeze button is a separate control and worth understanding. It overrides the thermostat and runs the compressor continuously for a period, then reverts. It's for use before adding a large quantity of fresh food, not as a permanent setting. On some older models it doesn't cancel itself, and leaving it on runs the compressor indefinitely.
Power cuts and holidays don't require dial changes. A freezer full of frozen food will hold safe temperatures for many hours unopened, and turning the dial up beforehand achieves very little.
And if the dial has worn markings — common on older appliances — the direction is still recoverable. The stop at one end is warmest and the stop at the other is coldest, and turning it clockwise almost always makes it colder.
Where the thermometer reads correctly but food still seems to be suffering, the setting probably isn't the problem. Frost building up on packaging, ice crystals forming inside bags and freezer burn on the surface of meat all point at air reaching the food rather than at temperature. That's a packaging and door-seal question rather than a dial question, and turning the setting colder won't fix it.
Position within the cabinet matters more than people expect on upright freezers. The top drawer is warmer than the bottom, sometimes by two or three degrees, because cold air sinks and because the top gets the most disturbance every time the door opens. If you're measuring, taking a reading in the top drawer as well as the middle tells you whether the spread is reasonable. Ice cream stored in the top drawer of a marginal freezer is the combination most likely to disappoint.
Chest freezers behave differently again. They stratify strongly, with the bottom several degrees colder than the top, and that's normal rather than a fault. Long-term storage goes at the bottom; things you'll use within a month can sit in the baskets near the top.
Common Mistakes Buyers Make
- Assuming 1 is coldest. It's the warmest on essentially every UK appliance.
- Reading the numbers as degrees. They're a relative scale with no fixed conversion.
- Setting it to maximum for safety. Wastes electricity and doesn't improve food safety below -18°C.
- Adjusting without measuring. A £4 thermometer replaces all the guesswork.
- Judging a change within an hour. The cabinet takes a day to stabilise across several compressor cycles.
- Never adjusting for a garage freezer. An unheated space swings enough through the year to warrant a seasonal change.
- Leaving fast freeze permanently on. It overrides the thermostat, and on older models it doesn't always cancel.
- Turning the dial to fix a fridge-freezer in a cold room. That's a placement problem and no setting solves it.
Alternatives Worth Considering
A freezer thermometer at a few pounds is the single most useful purchase here. It converts an ordinal dial into an actual measurement and takes the guesswork out permanently.
A fridge-freezer with a digital display removes the problem at the point of purchase. You set a temperature and the appliance reports what it's achieving. Worth the premium if you find the numbered dial genuinely irritating.
For anyone with a freezer somewhere they don't check often, a thermometer with a max-min memory or an alarm is worth the extra. It tells you if the appliance drifted while you weren't looking, which is exactly the failure mode a garage freezer has.
And a plug-in energy monitor is a useful companion. If you drop the setting by one and the weekly consumption falls noticeably while the thermometer still reads -18°C, you've found free money.
Frequently Asked Questions
Is 1 or 7 colder on a freezer?
7 is colder. On virtually all UK appliances, 1 is the warmest setting and the highest number is the coldest.
What number should a freezer be set to?
Usually the middle — 3 or 4 on a 1-7 dial. The only way to be sure is to measure with a thermometer.
Do the numbers mean degrees?
No. They're a relative scale controlling how long the compressor runs, with no fixed conversion to temperature.
What temperature should a freezer be?
-18°C. Above about -15°C, frozen food quality declines noticeably faster and stated storage times no longer hold.
Should I change the setting in summer?
In a garage or unheated room, yes — the same setting produces a warmer cabinet when the room is hot. In a heated kitchen it's rarely necessary.
Does a higher setting use more electricity?
Yes. A colder target means the compressor runs longer, so setting it to maximum unnecessarily costs money for no benefit.
Final Thoughts
The dial is a direction control, not a temperature control, and once that's clear the rest follows. Higher is colder, the middle is usually about right, and a thermometer settles it properly for the price of a coffee.
The single change worth making today is to buy one and leave it in the middle of the freezer for a day. Most people find they're within a degree or two of correct and can stop thinking about it. A minority find they're at -12°C and have been losing quality on everything for years.
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