This Running Weight Calculator Will Find Your Ideal Running Weight

by Zach Nehr

Blog ▸ This Running Weight Calculator Will Find Your Ideal Running Weight

When it comes to running weight performance, skinner is not always better – and in most cases, it is worse. Being fit and lean is one thing, but looking rail-thin is another. The fastest runners in the world are not rail-thin, especially in triathlon. 

If you looked at a room filled with the world’s top triathletes, few would guess that these men and women are endurance athletes. Today’s pro triathletes are built and muscular, fit, and strong. Not rail-thin, they no longer look like they could snap in half. 

Running Weight Performance

For running weight performance, the same holds true. Below, we have the Ideal Running Weight Calculator – but this is for entertainment purposes. The Calculator will produce a super-humanely light number, but this should not be your goal. Instead, your ideal running weight is likely 10-30 lbs heavier than the Calculator’s suggestion, and we’ll explain more below. 

Ideal Body Weight

Before we get into the numbers, it is important to remember that lighter is better, healthier is best. The best running performance does not come from continuously losing weight, and your ideal body weight is not the lightest you could possibly be.

It is easy to get fixated on the numbers and chase a lower and lower weight for running. Even losing a few pounds can hurt your performance if you are already very lean. In reality, the Ideal Running Weight Calculator should be something fun to look at, but in no way should it be a guide or a goal

Healthy training and nutrition habits will lead to the best race performances, not crash-dieting and under-fueling

With that said, let’s get into it. 

Plug Your Numbers into the Running Weight Calculator

The Ideal Running Weight Calculator says that lighter is better. However, this doesn’t translate to human running performance or psychology. So instead of using this “ideal body weight” as a goal, use it for entertainment only. 

This Calculator is based on math, and it shows that better power-to-weight will improve your running performance. However, these numbers do not represent a healthy weight range, so they should be discounted. 

I can hear you asking: What is the point of all this?! 

Well, there is an optimal running weight for everyone. Though finding it is harder than plugging your numbers into a calculator, we’re here to help guide you through the process. In the following paragraphs, we’ll show you how to find your ideal race weight. 

What is Ideal Running Weight?

Some of the best distance runners of all time were surprised when they found their ideal running weight. Ryan Hall, for one, said that his performances plummeted when he got too skinny. Other top runners had their best performances come when they thought they were 10 lbs overweight. 

Your ideal running weight will also be unique, and it is up to you to find it. Remember that lighter is faster, but healthier is fastest. Though the Ideal Running Weight Calculator may tell you to lose weight, that isn’t always the best option. 

How to Use the Ideal Running Weight Calculator

Using the Ideal Running Weight Calculator is more than just plugging in your numbers – especially when it comes to weight, nutrition, and body image. There are a few things that you need to know before making any significant lifestyle changes. 

Each section will give you a better understanding of running weight and ideal running weight. At the end of this post, we’ll wrap it up and explain how you can lose or gain weight (in a healthy way) and achieve your ideal running weight. 

Here’s what we’ll cover in the following  paragraphs: 

  • The Connection Between Ideal Running Weight and Body Fat Percentage
  • How to Calculate your Ideal Body Fat Percentage
  • How to Lose or Gain Weight (in a Healthy Way)

The Connection Between Ideal Running Weight and Body Fat Percentage 

Studies suggest that there is no correlation between body weight and triathlon performance. That’s an interesting thought because the maxim for years was that ‘skinnier is better.’ But nowadays, endurance athletes are bigger and stronger than ever.

That’s the key: heavier, fitter, and more muscular triathletes are stronger. Regardless of frame size, their total muscle mass helps improve sports performance, even when they’re not at a reduced weight.

Records are being broken every single year in the world of triathlon, and it doesn’t seem like a coincidence. Body weight may affect running performance alone, but it is mostly insignificant in the world of triathlon. 

On the bike, the ideal racing weight may be heavier than you think. More power equals more speed on a flat section of road – and most triathlon bike courses are flat. It is only when gradients reach 5+% that body weight negatively affects cycling performance. 

Body Composition is a Predictor of Endurance Performance

The actual correlation between the body and endurance performance is body composition. Studies have shown that body composition is correlated with triathlon times, specifically in IRONMAN. 

Body composition describes the percentages of muscle, fat, bone, and other tissues in a human body. You can test your body composition using a Dual X-ray Absorptiometry (DXA) scan. Body composition has little to do with ideal weight, and more with the weight ratio of your fat, body’s muscle mass, and essential fat.

One of the most important pieces of body composition is body fat percentage, or the percentage of your body’s tissue made up of fat. Here is a table with a range of body fat percentages from the World Health Organization: 

When it comes to running and triathlon performance, a lower body fat percentage is better. Read that carefully: the lowest weight is not the optimum racing weight. It is all about body fat percentage.

Your ideal running weight is achieved when you have a lower percentage of body fat and a higher percentage of muscle. Again, this does not necessarily mean that you have to be at a low weight to achieve peak performance.

Comparing Two Different Body Compositions

Take two different athletes; both stand six feet tall and weigh 190 lbs. These athletes are the same based on body weight and Body Mass Index (BMI – more on that in a minute). 

But let’s say Athlete #1 has a body fat percentage of 15%, whereas Athlete #2 has a body fat percentage of 35%. 

Athlete #1 has a significantly lower body fat percentage and thus a higher muscle percentage in their body. This athlete is much stronger and much faster than Athlete #2 whole higher percentage of body fat is only slowing him down. 

Muscle = strength and strength is everything in the world of athletics. Body fat can’t help you run faster – it will only be slowing you down. 

How to Calculate your Ideal Body Fat Percentage 

Using the chart above, you can find your healthy body fat percentage range based on your sex and age. It is important to note that this is a healthy range for most people. Of course, being outside this range makes it possible to be a successful runner and athlete.

Genetics, upbringing, and athletic history help determine whether our body type is lean, muscular, or built on a large frame or a small frame. Importantly, there is no “perfect body type” for running or any other sport. Certain traits may assist in the biomechanics of running, for example. But there are still top-level runners with tall frames, short frames, and built or lean. 

When it comes to ideal body fat percentage, use the chart above as a rough guide. It is also important to note that body fat percentage is entirely separate from body mass index, or BMI. 

BMI is a basic measure of body fat based on height and weight. We caution against using this measurement because it doesn’t consider lean body mass, body composition, or body type. In other words, it is practically useless – yet it is still a popular measurement used in health and fitness. 

For example, take an elite rugby player who is 6 feet tall and weighs 225 lbs. They are one of the fittest people on the planet – they are strong and muscular, quick and agile. They can run over 7km in a match while competing in tackles and scrums. But according to the BMI calculator, this rugby player is obese and unhealthy. You can see how wrong this is.

You can calculate your BMI here (but don’t read too much into the results).

How to Lose or Gain Weight (in a Healthy Way)

Weight loss is one of the million-dollar questions in society. You would be a billionaire if you invented a pill that helped people lose 15 lbs instantly with zero side effects.  

Your goal is to achieve your best running performance by altering your weight. And not everyone needs to lose weight. Some runners, like Ryan Hall, may have gotten too lean and weak. These athletes need to gain healthy weight in the form of muscle, which will make them stronger and faster runners. 

For many of us, the optimal weight for running is lower than what we currently weigh. Whether you are trying to improve your run times or reach the optimal racing weight, here are some tips for healthy weight loss

  1. Dial it back: when starting your weight loss journey, you don’t need to go all-in on Day 1. You don’t need to start weighing your food, cutting your calories in half, or fasting to lose weight. Healthy and sustainable weight loss occurs in small increments over long periods of time. 
  2. Train in the correct zone: training at too high of an intensity can cause excess inflammation, cortisol, and lactate build-up. Overtraining can lead to your body retaining excess weight and fitness stagnation. Not good. 
  3. Use Zone 2 training: spending ~80% of your training time in Zone 2 will increase your fat burning rate, improve your metabolism, improve your aerobic fitness, and so much more. It’s no secret that Zone 2 is the best training zone for endurance athletes. . Calculate your Zone 2 Heart Rate here using our HR Training Zone Calculator
  4. Use polarized training: the remaining 20% of your training time should be spent in Zones 4 and 5, or close to maximum efforts. These workouts consist of short intervals ranging from 15-second sprints to 8-minute efforts, and they will stimulate your metabolism for 24-48 hours following the workout. Plus, they make you a lot stronger.
  5. Caloric deficit: to lose weight, you need to burn more calories than you can consume. It is the definition of “easier said than done.” You can calculate the number of calories you should be eating using the NASM Calorie Calculator. This tool from the National Academy of Sports Medicine accounts for your height, weight, and age, as well as your activity level, macronutrient breakdown of your diet, and goal weight. 

Remember that weight loss or gain is about much more than running performance – it is about feeling good, looking good, and feeling confident about your body. You can also use the tips above to gain healthy weight. Just reverse some of the wording in the steps above and focus on making small weight gains rather than big ones. 

We recommend speaking with a certified sports nutritionist for guidance on weight and diet. Competitive runners may put themselves at risk when training for a big race, as their energy levels may dip under the stress of training.

Remember to fuel your workouts, especially those with hard efforts (above Zone 2). During racing season, it’s best to focus on improving your performance while you maintain your weight. Trying to lose weight during racing season is a recipe for disaster.

In running performance, your goal should be to lose or gain weight healthily and sustainably. Long-term gains are the happiest and healthiest, ultimately leading to your best running performance. 

For the complete guide on weight loss for triathletes, check out our free guide here


Healthier, fitter, and more muscular athletes are the strongest endurance athletes and the fastest runners. The Ideal Running Weight Calculator is meant for entertainment purposes only. Additionally, lighter does not always mean faster, whereas being overweight doesn’t help. 

Somewhere in the middle of being underweight or overweight, there is a sweet spot for your Ideal Running Weight. Many elite runners have found this weight to be 10-20 lbs heavier than the number spit out by the Ideal Running Weight Calculator, but that is not necessarily true for everyone. 

Whether you are trying to lose weight, run faster, or better your health, remember that the Ideal Running Weight Calculator is just for fun. Your true running weight is out there, waiting for you to find it. Lighter is better, healthier is best

Here’s the Ideal Running Weight Calculator (to use for fun):

Zach Nehr

Zach Nehr

Zach has a degree in Exercise Science and Psychology. He is a certified coach, Cat 1 cyclist, and is a freelance writer having been published in many of the worlds largest endurance sports publications.

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