An audio baby monitor comprises two parts, one that stays in the nursery (baby or nursery unit) and one you keep on you, either somewhere propped up in the room you're in or clipped to your belt as you get on with other stuff while your baby sleeps.
A video baby monitor also has two parts, but the baby unit includes a camera that sends pictures back to the parent unit, so you can see your baby as well as hear them. Some are quite basic, but on more expensive models you can get cameras that pan around the room, or even zoom in.
The parent unit on a video baby monitor varies: some have a massive screen so you can get a large picture, while others are much smaller, which limits what you can see.
Which one you choose will depend on how much you want to spend and your personal preference. Some parents like to be able to see their little one breathing, while others are fine with just being able to hear if they're needed.
Smart wi-fi video baby monitors
Although some wi-fi baby monitors have parent units, you usually monitor your baby using your smartphone or tablet via a compatible app.
While a parent unit on traditional baby monitors will only work in the house and maybe as far as the garden, a smart wi-fi monitor isn't constrained by signal range and can work wherever you are as long as you have decent wi-fi signal.
This means if you're missing your little one you can check in when you’re at work or away from home.
Our tests have shown huge differences in terms of signal range and battery life.
The worst baby monitor on test will only allow you get as far as 15 metres away before losing signal, and the battery won't even last for an evening, which essentially means it's more of a hindrance than a help when it comes to helping you look after your child.
Test out the sound clarity on a baby monitor throughout your home as soon as you buy it. Most have a variety of channels to use – useful if you live in a built-up area which will be more susceptible to interference or static.
Analogue-signal baby monitors are the most open to accidental broadcast, as this can easily be picked up on normal radios and other people's monitors. This is less likely with digital monitors, although it does still happen.
A digitally enhanced cordless telecommunications (DECT) baby monitor has a microprocessor designed to ensure that the only nursery sounds you can hear are those from your own nursery, not anyone else's.
Our tests check for interference from other devices, as well as assessing the clarity and volume of the sound.
The range of a baby monitor indicates how far you can travel with the parent unit and still receive an accurate signal.
Many manufacturers make bold claims when stating range – some say you'll still get a signal up to 600 metres away.
Looking more closely at these claims shows, generally, that this is the distance the signal can travel if both units are outside in an open space. This isn't much use if you mainly use your monitor indoors, or when your baby is asleep inside and you're in the garden.
We've found that on a good baby monitor you'll be able to move the parent unit more than 80 metres away from the baby (or nursery) unit without losing the signal. On a poor monitor, you won't get much further than 20 metres.
With wi-fi baby monitors, the signal is as strong as your internet connection - both to your smartphone/tablet, and the baby unit in the nursery. Do bear that in mind when considering a smart wi-fi monitor.
The type of property can make a difference, too. Older houses have thicker walls that can sometimes cause problems with the signal, whereas modern houses have thinner walls so the signal can travel more easily.
We test baby monitors in both types of property to find out which perform best.
How much do I need to spend on a baby monitor?
You can spend less than £20 for a basic audio monitor, or more than £300 for a top-of-the-range model with multiple cameras. An expensive, feature-packed baby monitor doesn't mean it will be the perfect piece of baby safety equipment for you, so we test its key features, such as battery life and signal strength.
With Best Buy baby monitors from as little as £35, there's a baby monitor you can rely on no matter what your budget is.
My house is really small, do I need a baby monitor?
Some households find they can function perfectly well without a baby monitor, as any cries can be heard through an open door or thin walls. But even so, there are still reasons why you might need one:
If you have a cat or dog, you may want to shut the nursery door.
Gardening or laundry will take you outside, where you won’t be able to hear a crying baby.
If you're hard of hearing, the visual element of the monitors, such as sound-sensitive lights or vibration mode, can be a big help. Our lab tests assess how accurate the sound-sensitive lights are and make sure that they increase in line with the volume output, so you don't miss when your baby needs you.
Homeowners with thick walls will find baby monitors essential, as their house is effectively sound-proofed.
To be safe, the baby monitor should be placed at least a metre (or 3ft) away from a cot, crib or play area.
How to set up your baby monitor safely
Whatever type of monitor you choose, you'll need to consider how and where you place the baby unit near your child so you can hear and see them while they sleep, but so there are no safety concerns.
Current guidance states that you should avoid attaching a monitor to a baby's cot, as there could be a risk of it falling into the crib or the baby getting caught in any cables.
Additionally, if any parts, such as screws, become loose they could pose a choking hazard to the baby.
For older children that can stand or kneel, there is a risk that the monitor could be used as a foothold for them to climb out of the cot, alongside a strangulation risk with any cables.
Always keep any wires, cords or cables well out of the way of babies and toddlers. As your baby gets bigger and older, keep checking regularly that he or she still can't reach them.
Ideally, the baby monitor should be placed at least one metre (or 3ft) away from a cot, crib or play area.
Consider placing it on nearby furniture or shelves so that if the monitor has video capability, it gives a good enough view of your baby's sleeping position.
You could also consider wall mounting the monitor if it has the required fittings, but be careful of any dangling cables.
Positioning an audio monitor is much easier as it just needs to be close enough to capture the sound of your baby crying.
Baby monitors with a motion sensor mat or pads
Some baby monitors come with motion sensors. These are marketed as a tool to protect against sudden infant death syndrome (SIDS), also known as cot death.
The motion-sensor pads or mat detects your baby's movements, even the slightest ones. If your baby stops moving for more than 20 seconds, an alarm sounds and red lights flash.
Some parents find them really reassuring, however they can cause more worry when false alarms happen, and you may find they create more anxiety.
Infant safety charity The Lullaby Trust says there's no evidence that this kind of monitoring can prevent SIDS.
Choose a baby monitor and the optional extras that will suit you and your baby best.
Find the perfect baby monitor for you and your baby with ourbestbaby monitors.
Where to buy a baby monitor
When buying a baby monitor, make sure you're handing your money over to a reputable seller. Check the retailer's returns policy and pay attention to customer feedback and reviews. For more details on shopping online safely and arranging refunds for faulty products, see our advice on shopping online.
Argos, Amazon, John Lewis and Boots are some of the most searched-for baby monitor retailers at the time of writing. We’ve included links to these retailers handpicked because of their stock availability, best value price or warranty options.
Argos – sells a mixture of video and digital audio baby monitors. Prices start at around £20 for basic models and go up to nearly £400. Argos offers same day in-store collection at selected Sainsbury's stores and you can even bump up your nectar points when you shop there.
Amazon – has hundreds of baby monitors in stock, but check the listing carefully, some tech may not be UK models. You should also try to stick to products that are fulfilled by or sold by Amazon if you can, it’s much easier to resolve issues if something goes wrong.
John Lewis – sells a range of baby monitors from brands including Angelcare, Babymoov and Nanit. Prices start at around £30 and go as high as £300. Most of the baby monitors come with a one or two year warranty at no extra cost and John Lewis generally scores highly in our annual retailer survey of more than 2,000 members of the public.
Boots – stocks a small range of baby monitors, with the majority from Motorola, Angelcare and BT. Prices vary from £30 to £300, which means you will get free home delivery or in-store click and collect. If you opt for buying at Boots you can also get points on your advantage card.