How Many Amps Does a 12V Fridge Draw? (Real Numbers by Fridge Size)
Sizing guide · 7 minute read · Written for car camping, van life and RV owners in the US
Ask ten campers how many amps a 12V fridge draws and you will get ten confident answers. Most of them are measuring different things. Amps, watts and amp-hours get used as if they were interchangeable. They are not, and that mix-up is why so many people size a battery or a power station wrong.
The good news: once you separate the three, the arithmetic is simple. You do not need a spec sheet for every model. You need to know which number is a rate and which number is a total.
The three units people mix up
One sentence each, because this is the whole confusion:
- Amps (A) is a rate — the flow of current right now, while the compressor is running.
- Watts (W) is also a rate, but it includes voltage, so it is the better unit to plan with.
- Amp-hours (Ah) is a total — amps multiplied by hours. This is what your battery stores.
The link is Ohm's law in its easy form: on a 12V circuit, watts equal amps times 12. So a fridge pulling 4 A is drawing about 48 W. A fridge pulling 5 A is drawing about 60 W. Same circuit, same voltage.
Watts = amps × volts. Amp-hours = amps × hours.
Why a running-draw amp figure is not an hourly average
Here is the trap. When a spec sheet says "5 A," that is the draw while the compressor runs. It is not five amps for every one of the 24 hours in a day.
A compressor fridge works like your kitchen fridge. It runs, cools the box down to the set temperature, stops, then waits. When the inside warms back up, it starts again. The share of the time it is actually running is the duty cycle.
If you multiply 5 A by 24 hours, you assume the compressor never stops. It does. In mild weather a compressor fridge might run for only a third to a half of the day. So treating a running amp figure as an hourly average can overstate your daily need by double or more.
How duty cycle turns amps into amp-hours
One more formula and you have the whole method:
Amp-hours per day = running amps × hours the compressor runs per day
That is it. You take the running draw in amps, then multiply by the hours it actually runs — not 24. The result is the total your battery has to hand back over a day.
Notice you never need the amps to be exact. A small error in the running draw matters far less than a big error in the run-hours. That is where the guesses usually go wrong.
Example values by fridge size
The table below is a method, not a spec sheet. The amp and hour figures are clearly-labelled example assumptions. Replace them with your own model's draw and your own conditions.
| Fridge size (example) | Running draw (assumed) | Run-hours per day (assumed) | Amp-hours per day |
|---|---|---|---|
| Small | 4 A (≈48 W) | 8 h | 32 Ah |
| Mid | 5 A (≈60 W) | 10 h | 50 Ah |
| Large | 6.5 A (≈78 W) | 12 h | 78 Ah |
Read the last column, not the second. The amp figure on its own tells you almost nothing. The amp-hours per day is the number you design around. A larger fridge draws more amps and tends to run longer hours, so the two effects stack.
Why hot weather and frequent opening push it up
Those run-hours are the moving part. Two things move them a lot.
Heat. A fridge in a 95°F vehicle works harder than the same fridge in 68°F. Over a hot afternoon the compressor runs longer for every degree of difference between the box and the air around it. Camp in the desert in July and your run-hours climb well past any mild-weather guess.
Opening the lid. Every time you open it, cold air spills out and the compressor has to catch up. A fridge used as a drinks cabinet at a campsite runs far more than one opened twice a day. Small habit, big effect on the daily total.
A related factor is how full the box is. Contents act as thermal mass, so a full fridge holds its temperature and cycles less than a nearly empty one.
Want the numbers done for you?
The free 3-page Portable Fridge & Power Buying Checklist walks through this same formula, then the 7 fridge checks, the 8 station checks and the 24-hour test — in order.
What this means when you shop batteries and stations
Now the payoff. Your amp-hours per day is the demand. Whatever you buy to meet it is the supply. Compare demand to usable supply and the decision stops being a guess.
Two cautions when you translate to shopping:
- A battery's rated amp-hours is not the amount you can actually use. Draining it fully is hard on it, so its usable capacity is lower. Check your battery maker's published depth-of-discharge or usable-capacity figure.
- A power station's box capacity works the same way — the usable number is always below the rated one. Plan against the usable figure, not the sticker.
If your example came out at 50 Ah per day, a battery you can safely use 50 Ah from covers exactly one day, with nothing left for a cloudy one. That is usually too tight. Two days of usable capacity is the more comfortable target, so the numbers are your starting point, not your finish line.
Quick answers
How many amps does a 12V fridge draw?
Compressor fridges draw a modest running current — often single-digit amps on a 12V circuit — but the exact figure varies by model, size and compressor. Check your model's spec sheet for its running draw. The figure you actually plan with is amp-hours per day, not the instantaneous draw.
Is amps the same as amp-hours?
No. Amps is a rate — the flow right now. Amp-hours is a total — amps multiplied by hours. A fridge drawing 5 A while running for 10 hours uses 50 Ah that day. Confusing the two is the most common sizing mistake.
Does a 12V fridge draw amps continuously?
No. The compressor cycles on and off, so draw is near zero when it is idle and at its running figure when it is on. The duty cycle — the share of the day it runs — is what turns a running amp figure into a daily amp-hour total.
Keep reading
- How much power does a 12V fridge really use?
- How long will a 12V fridge run on a 100Ah battery?
- What size battery do you need for a 12V fridge?
- What size power station runs a 12V fridge?
This guide may contain affiliate links. If you buy through them, we may earn a commission at no extra cost to you. We only link to products that fit the numbers above. Frostamp is not an electrician or an electrical engineer — this is general information, not professional advice. Always follow the manufacturer's instructions for your exact model.