Life Jackets (PFDs)

—— Stay safe on the water with our durable and comfortable life jackets for all ages.

What size PFD do I need?

Do lifejackets have a weight limit?

These are just two questions (of many) that regularly surface when kicking off conversations about getting marine enthusiasts into the best PFD or life jacket for their adventures.

Whether you're looking for a PFD for a specific activity or trying to figure out what life jacket best suits your weight, we’ve lined up expert insights from the engineers here at Mustang Survival to help guide your PFD or life jacket selection. From kids' flotation options to adult PFDs—and even a PFD for dogs—we’re here to help you confidently navigate fit, function, and PFD sizing.

The answers to the ‘best PFD or life jacket’ questions might surprise you - and it’s all based on science. Come along for the ride as we explain buoyancy and how choosing a PFD comes down to two simple questions.

What is Buoyancy?

Buoyancy is the upward force of a body of water or fluid that gets applied to any object entering it, that opposes the weight of that object, whether fully or partially submerged. The amount of buoyancy applied to an object is dependent on how much water the object moves (or displaces) when it enters the water.

If the object moves less water than its weight, it’ll sink. If it moves more or an equal amount to its weight, it will float.

What’s interesting is what happens to, and with, the human body while in water. And, how the principles of buoyancy involve thinking beyond weight, and into a whole world of factors. Essentially—and in an oversimplified statement—bodies get lighter. A LOT lighter.

How Much Buoyancy is Required?

The United States Coast Guard has published on their Boating Safety website that ‘most adults only need 7 to 12 pounds of buoyancy (31 to 53 Newton) to keep their heads above water’.  

How Does Buoyancy Get Calculated?

There is no ‘one equation’ that computes weight into in-water weight; factors like body composition, height, shape, weight distribution, and aspects of the physical body unique to each human being are too vast to reliably and consistently quantify it. Something as simple as someone inhaling can affect their body’s buoyancy (making them more buoyant as they fill their lungs, and less when they empty them).

Nonetheless, there is a general rule-of-thumb system put into place that takes into account all these nuances.  

A common misconception is that individuals with a higher body weight assume they need a PFD  PFD or life jacket that offers the highest amount of buoyancy (the greatest number of pounds of support). When in actuality, a body’s weight on land doesn’t indicate how much poundage you need. Its composition is what brings buoyancy into perspective: the leaner (the less body fat you have), the higher buoyancy you require. This is where a life jacket fit guide can help you determine what works best for your body type.

The Engineering Behind Mustang Survival PFDs

When Mustang Survival engineers create a new PFD or life jacket or optimize an existing one, they go beyond simply designing something to bring the wearer to the water’s surface. Depending on the PFD sizing and design, they also aim to turn the wearer onto their back while floating. 

Their focus is on engineering precise angles: the angle of the wearer’s face to the water and the position of their mouth when floating. The goal is to ensure that the head and mouth are as high out of the water as possible. As a result, the best PFD or life jackets consider more than buoyancy as a means of providing lift or up thrust to raise the wearer above the surface.

Here’s where it gets tricky: body weight and weight distribution *can* impact those angles they engineer for. It’s something that can’t be avoided (again, with the uniqueness of each body), yet should be noted when choosing the PFD best suited to you, and what you’re heading out to do.

Does Everyone Require the Same Buoyancy?

Choosing the right personal flotation device (PFD) or life jacket isn't just about style or fit—it's about understanding how much buoyancy you need to stay afloat, comfortably and safely, in real-world conditions.

Buoyancy is the upward force that keeps you afloat in water. But contrary to popular belief, more isn’t always better—you want just enough lift for your body type, activity, and environment. 

Below, we break down common buoyancy questions our Customer Experience team receives to help you make a confident, informed choice.

How Much Buoyancy Do Adults Need in a Life Jacket?

Most adults need between 7–12 lbs (31–53 Newtons) of buoyancy to stay afloat with their head safely above water. The exact number depends on several factors:

• Body composition: Leaner individuals or those with low body fat often need more buoyant lift.

• Size and weight: Larger adults may require more lift, especially if wearing heavy gear.

• Clothing layers: A life jacket needs to counter the added weight of boots, jackets, and gear in the water.

• Environment: Calm inland paddling requires less buoyancy than rough offshore boating or cold-water rescue.

Higher-buoyancy options, like inflatable PFDs, provide 15 lbs or more of lift—great for anglers, offshore boaters, and professionals who want less bulk but need reliable flotation.

Quick Example…

Let’s say you weigh 180 lbs (about 82 kg). You don’t need 180 lbs of buoyancy to stay afloat—your body is already mostly water, which is neutrally buoyant. On average, only 8–12 lbs of lift are needed to keep your head and airway safely above water. That’s where your PFD comes in. 

How Much Buoyancy Do Kids Need in a Life Jacket?

Unlike adult PFDs, children’s life jackets aren’t labeled by pounds of buoyancy—they’re sized by body weight ranges. This ensures that each design provides the right lift and flotation angle for a child’s unique proportions, especially their larger head-to-body ratio.

Why You Can’t Use a Formula for Kids

Buoyancy isn’t one-size-fits-all, especially for kids. Factors like muscle mass, body fat, and posture all influence how a child floats. That’s why we build kid-specific safety features (like grab handles and head support) into each weight category.

Dive deeper: Most Asked Kids’ PFD Question

How Much Buoyancy Does a Dog Life Jacket Need?

There’s no standard “buoyancy number” for dogs, but that doesn’t mean performance should be a guessing game. A good dog life jacket—like our Underdog Life Vest—should be chosen based on:

• The dog’s weight and breed

• Body shape and buoyancy needs

• Swimming ability and activity level

Look for these key features:

• Full-body support and head flotation

• Grab handle for easy lift-in/out of the water
  Adjustable straps for a secure, balanced fit

We recommend trying the jacket in shallow water first to make sure your pup floats safely and comfortably, before heading out on longer trips.

Example Calculation

To understand how personal flotation devices (PFDs) keep you afloat, let’s break down the physics using a 200-pound person as an example. Roughly 80% of the human body is water, which effectively weighs nothing in water, leaving only 20% of body weight that must be supported. 

That’s 200 lbs × 20% = 40 lbs. 

At first glance, this may raise questions since many life jackets offer only 15–22 lbs of buoyancy. But body fat also plays a crucial role: about 15% of body weight is fat, and fat is lighter than water. 

So 200 lbs × 15% = 30 lbs of fat providing natural flotation. Subtracting that from the 40 lbs needing support leaves just 10 lbs that the PFD must keep afloat.

For added context, a PFD with 22 lbs of buoyancy provides more than double the lift needed in this scenario. Even someone weighing 250 pounds with a similar fat percentage would only require about 12.5 lbs of assisted buoyancy (250 lbs × 20% = 50 lbs; 250 lbs × 15% fat = 37.5 lbs; 50 – 37.5 = 12.5 lbs). 

From - Mustang Survival (How to choose a PFD or Life Jacket)

Why Properly Fitted Kids’ Life Jackets Matter

Fast forward to today, and more families are heading out on the water to give their kids a taste of life on the ocean. That means the need for properly sized, kid-specific PFDs—and a better understanding of why fit matters—is more important than ever.

Helping kids stay safe and be part of the fun has always been part of the Mustang Survival mission. But designing flotation gear for young bodies hasn’t been a simple copy-paste from adult models. Kids are more compact. That changes the game when it comes to flotation.

Where adults have longer limbs and varied weight distribution, kids are shaped more like a ball. Mustang Survival engineers around this unique shape, designing youth PFDs to keep kids floating on their backs with their faces out of the water. And that’s exactly why weight-based sizing matters—because getting the right fit is more than comfort; it’s a matter of safety.

What size PFD do I need?

Do lifejackets have a weight limit?

These are just two questions (of many) that regularly surface when kicking off conversations about getting marine enthusiasts into the best PFD or life jacket for their adventures.

Whether you're looking for a PFD for a specific activity or trying to figure out what life jacket best suits your weight, we’ve lined up expert insights from the engineers here at Mustang Survival to help guide your PFD or life jacket selection. From kids' flotation options to adult PFDs—and even a PFD for dogs—we’re here to help you confidently navigate fit, function, and PFD sizing.

The answers to the ‘best PFD or life jacket’ questions might surprise you - and it’s all based on science. Come along for the ride as we explain buoyancy and how choosing a PFD comes down to two simple questions.

What is Buoyancy?

Buoyancy is the upward force of a body of water or fluid that gets applied to any object entering it, that opposes the weight of that object, whether fully or partially submerged. The amount of buoyancy applied to an object is dependent on how much water the object moves (or displaces) when it enters the water.

If the object moves less water than its weight, it’ll sink. If it moves more or an equal amount to its weight, it will float.

What’s interesting is what happens to, and with, the human body while in water. And, how the principles of buoyancy involve thinking beyond weight, and into a whole world of factors. Essentially—and in an oversimplified statement—bodies get lighter. A LOT lighter.

How Much Buoyancy is Required?

The United States Coast Guard has published on their Boating Safety website that ‘most adults only need 7 to 12 pounds of buoyancy (31 to 53 Newton) to keep their heads above water’.  

How Does Buoyancy Get Calculated?

There is no ‘one equation’ that computes weight into in-water weight; factors like body composition, height, shape, weight distribution, and aspects of the physical body unique to each human being are too vast to reliably and consistently quantify it. Something as simple as someone inhaling can affect their body’s buoyancy (making them more buoyant as they fill their lungs, and less when they empty them).

Nonetheless, there is a general rule-of-thumb system put into place that takes into account all these nuances.  

A common misconception is that individuals with a higher body weight assume they need a PFD  PFD or life jacket that offers the highest amount of buoyancy (the greatest number of pounds of support). When in actuality, a body’s weight on land doesn’t indicate how much poundage you need. Its composition is what brings buoyancy into perspective: the leaner (the less body fat you have), the higher buoyancy you require. This is where a life jacket fit guide can help you determine what works best for your body type.

The Engineering Behind Mustang Survival PFDs

When Mustang Survival engineers create a new PFD or life jacket or optimize an existing one, they go beyond simply designing something to bring the wearer to the water’s surface. Depending on the PFD sizing and design, they also aim to turn the wearer onto their back while floating. 

Their focus is on engineering precise angles: the angle of the wearer’s face to the water and the position of their mouth when floating. The goal is to ensure that the head and mouth are as high out of the water as possible. As a result, the best PFD or life jackets consider more than buoyancy as a means of providing lift or up thrust to raise the wearer above the surface.

Here’s where it gets tricky: body weight and weight distribution *can* impact those angles they engineer for. It’s something that can’t be avoided (again, with the uniqueness of each body), yet should be noted when choosing the PFD best suited to you, and what you’re heading out to do.

Does Everyone Require the Same Buoyancy?

Choosing the right personal flotation device (PFD) or life jacket isn't just about style or fit—it's about understanding how much buoyancy you need to stay afloat, comfortably and safely, in real-world conditions.

Buoyancy is the upward force that keeps you afloat in water. But contrary to popular belief, more isn’t always better—you want just enough lift for your body type, activity, and environment. 

Below, we break down common buoyancy questions our Customer Experience team receives to help you make a confident, informed choice.

How Much Buoyancy Do Adults Need in a Life Jacket?

Most adults need between 7–12 lbs (31–53 Newtons) of buoyancy to stay afloat with their head safely above water. The exact number depends on several factors:

• Body composition: Leaner individuals or those with low body fat often need more buoyant lift.

• Size and weight: Larger adults may require more lift, especially if wearing heavy gear.

• Clothing layers: A life jacket needs to counter the added weight of boots, jackets, and gear in the water.

• Environment: Calm inland paddling requires less buoyancy than rough offshore boating or cold-water rescue.

Higher-buoyancy options, like inflatable PFDs, provide 15 lbs or more of lift—great for anglers, offshore boaters, and professionals who want less bulk but need reliable flotation.

Quick Example…

Let’s say you weigh 180 lbs (about 82 kg). You don’t need 180 lbs of buoyancy to stay afloat—your body is already mostly water, which is neutrally buoyant. On average, only 8–12 lbs of lift are needed to keep your head and airway safely above water. That’s where your PFD comes in. 

How Much Buoyancy Do Kids Need in a Life Jacket?

Unlike adult PFDs, children’s life jackets aren’t labeled by pounds of buoyancy—they’re sized by body weight ranges. This ensures that each design provides the right lift and flotation angle for a child’s unique proportions, especially their larger head-to-body ratio.

Why You Can’t Use a Formula for Kids

Buoyancy isn’t one-size-fits-all, especially for kids. Factors like muscle mass, body fat, and posture all influence how a child floats. That’s why we build kid-specific safety features (like grab handles and head support) into each weight category.

Dive deeper: Most Asked Kids’ PFD Question

Why Properly Fitted Kids’ Life Jackets Matter

Fast forward to today, and more families are heading out on the water to give their kids a taste of life on the ocean. That means the need for properly sized, kid-specific PFDs—and a better understanding of why fit matters—is more important than ever.

Helping kids stay safe and be part of the fun has always been part of the Mustang Survival mission. But designing flotation gear for young bodies hasn’t been a simple copy-paste from adult models. Kids are more compact. That changes the game when it comes to flotation.

Where adults have longer limbs and varied weight distribution, kids are shaped more like a ball. Mustang Survival engineers around this unique shape, designing youth PFDs to keep kids floating on their backs with their faces out of the water. And that’s exactly why weight-based sizing matters—because getting the right fit is more than comfort; it’s a matter of safety.

How Much Buoyancy Does a Dog Life Jacket Need?

There’s no standard “buoyancy number” for dogs, but that doesn’t mean performance should be a guessing game. A good dog life jacket—like our Underdog Life Vest—should be chosen based on:

• The dog’s weight and breed

• Body shape and buoyancy needs

• Swimming ability and activity level

Look for these key features:

• Full-body support and head flotation

• Grab handle for easy lift-in/out of the water
  Adjustable straps for a secure, balanced fit

We recommend trying the jacket in shallow water first to make sure your pup floats safely and comfortably, before heading out on longer trips.

Example Calculation

To understand how personal flotation devices (PFDs) keep you afloat, let’s break down the physics using a 200-pound person as an example. Roughly 80% of the human body is water, which effectively weighs nothing in water, leaving only 20% of body weight that must be supported. 

That’s 200 lbs × 20% = 40 lbs. 

At first glance, this may raise questions since many life jackets offer only 15–22 lbs of buoyancy. But body fat also plays a crucial role: about 15% of body weight is fat, and fat is lighter than water. 

So 200 lbs × 15% = 30 lbs of fat providing natural flotation. Subtracting that from the 40 lbs needing support leaves just 10 lbs that the PFD must keep afloat.

For added context, a PFD with 22 lbs of buoyancy provides more than double the lift needed in this scenario. Even someone weighing 250 pounds with a similar fat percentage would only require about 12.5 lbs of assisted buoyancy (250 lbs × 20% = 50 lbs; 250 lbs × 15% fat = 37.5 lbs; 50 – 37.5 = 12.5 lbs). 

From - Mustang Survival (How to choose a PFD or Life Jacket)