Do you flex when taking body measurements? The Key to Accurate Tracking

October 2, 2025 •

5 min read

According to research, consistency is the single most important factor for obtaining reliable body measurements over time, surpassing whether you are flexed or relaxed. Therefore, in answering the question, do you flex when taking body measurements, the key is to choose one method and stick to it consistently for meaningful progress tracking.

Quick Summary

Whether to flex during body measurements depends on your goals, but consistency in your approach is the most critical factor for tracking progress reliably. Learn the best practices for accurate measurements for different body parts and fitness objectives.

Key Points

Consistency is paramount: The most important rule is to be consistent with your method, whether you measure relaxed or flexed, to get reliable data for tracking progress.
Relaxed is best for general tracking: For weight loss and general health monitoring, measuring in a relaxed state provides a more consistent and representative baseline.
Flexed is for muscle growth: Bodybuilders and strength athletes may choose to measure their muscles while flexed to track peak muscle size and hypertrophy.
Measure at the same time and under the same conditions: Always measure in the morning, before eating or exercising, and wear minimal clothing to minimize variables.
Use accurate tools and techniques: A flexible, non-stretchable measuring tape is crucial. Stand with consistent posture, measure at the same anatomical landmark, and ensure the tape is snug but not tight.
Waist should always be relaxed: Never suck in your stomach when measuring your waist, as this will result in an inaccurate reading. Breathe normally and measure after exhaling.

For anyone tracking fitness progress, understanding the best practices for body measurements is essential. While the number on the scale can fluctuate daily due to hydration, sodium intake, and other factors, circumference measurements offer a more nuanced view of changes in body composition, such as fat loss or muscle gain. The central question many people face is whether to flex their muscles or keep them relaxed during this process. The simple answer is that consistency trumps all, but the ideal method depends on your specific goals.

The Golden Rule: Consistency Above All

Whether you decide to measure relaxed or flexed, the most important rule is to remain consistent with your approach every time you measure. An inconsistent technique will render any results unreliable, making it impossible to accurately compare progress over time. For example, a relaxed bicep measurement one month followed by a flexed one the next will give a misleading indication of growth. The same applies to other factors such as the time of day, posture, and clothing worn.

Relaxed Measurements

For most individuals focused on general fitness, overall health, or weight loss, taking measurements in a relaxed state is the most common and recommended practice.

For Weight and Fat Loss: Relaxed measurements provide a baseline for overall body size, which is a key indicator of fat loss. As you lose fat, your relaxed measurements will decrease, offering clear evidence of progress even if the scale is not moving much due to simultaneous muscle gain.
For General Health: Many health organizations use relaxed waist measurements to assess visceral fat levels, which are linked to various health risks. A relaxed measurement offers a more accurate representation of your baseline health status.

Flexed Measurements

Flexing during measurements is generally reserved for those with specific bodybuilding or strength training goals. The purpose here is to track peak muscle size, rather than overall circumference.

For Bodybuilding: For bodybuilders, tracking the maximum size of muscles like the biceps, quads, or chest is a primary objective. Measuring while flexed allows them to document the true peak size of their muscles, which is a more meaningful metric for their specific sport. Some bodybuilders even track both relaxed and flexed measurements to assess both overall size and maximum potential.

How to Take Consistent Body Measurements

To ensure your measurements are as accurate and consistent as possible, follow these guidelines:

Measure First Thing in the Morning: Your body size can fluctuate throughout the day due to food, hydration, and muscle pumps from exercise. Taking measurements in the morning, on an empty stomach, minimizes these variables.
Wear Minimal, Fitted Clothing: Measure directly against the skin or over a single, thin layer of clothing to avoid adding extra inches.
Use the Right Tools: Always use a flexible, non-stretchable measuring tape. Inelastic cloth tapes are ideal, while stiff metal ones are unsuitable.
Maintain Consistent Posture: Stand up straight with your shoulders back and your feet together. Avoid slouching, holding your breath, or flexing your stomach muscles when measuring your waist.
Measure at the Same Location: Ensure the measuring tape is positioned at the same anatomical landmarks each time. For example, measure the waist at navel height or the natural waistline. Marking the location or noting a specific landmark can help.
Avoid Over- or Under-Tension: The tape measure should be snug against the skin but not tight enough to compress the tissue. It should also not be loose.
Record Your Results: Keep a log of your measurements, along with the date and any relevant notes, to track your progress effectively.

Comparison of Flexed vs. Relaxed Measurements


Feature	Relaxed Measurement	Flexed Measurement	Key Takeaway
Primary Goal	General health, weight loss, baseline tracking.	Tracking peak muscle size and hypertrophy.	Your goal dictates which method is more appropriate.
Consistency	Highly consistent, as there is less variation in a relaxed state.	Can be less consistent due to variations in flexing effort.	Standardizing your method is more important than the method itself.
Applicability	Suitable for all measurements (arms, legs, waist, hips).	Primarily for limbs like biceps, calves, and chest. Not suitable for waist measurements.	Relaxed is a more universal method for overall tracking.
Focus	Changes in fat and overall body composition.	Changes in muscle mass and muscular definition.	Different methods highlight different aspects of progress.
Recommended For	Most individuals tracking fitness progress or focusing on health outcomes.	Competitive bodybuilders or serious strength athletes.	Choose based on your specific fitness journey.

Conclusion

Ultimately, whether you decide to flex when taking body measurements is less important than your consistency in doing so. For the average person aiming for general health or fat loss, measuring in a relaxed state provides a more reliable and less variable metric for progress tracking. For the serious lifter or bodybuilder, measuring flexed allows them to track the maximum size of their muscles, which aligns with their specific goals. The key takeaway is to choose a method, apply it consistently under the same conditions (time of day, clothing, posture), and use a reliable tool. Remember that measurements are just one metric of progress; paying attention to how your clothes fit and how you feel can provide a more holistic view of your health journey. For further guidance on accurate body composition assessments, it's always wise to consult reliable health and fitness resources, such as those provided by trusted health organizations.

https://help.macrofactorapp.com/en/articles/118-tips-for-taking-good-body-measurements

How to Measure Specific Body Parts

Arms (Biceps/Triceps): With the arm bent at a 90-degree angle (or relaxed), measure around the fullest part of the bicep. Note whether you are measuring flexed or relaxed.
Waist: Find the narrowest part of your torso, usually above your belly button. Wrap the tape measure snugly around, making sure it's level, and take the measurement after a normal exhale.
Hips: Stand with feet together and measure the widest part of your hips and buttocks.
Thighs: Measure the widest part of your thigh, usually near the top, making sure the tape is level.

Tracking Your Results

Don't Obsess Over Daily Fluctuations: Your measurements can change day-to-day. A weekly or monthly check-in is a better indicator of long-term trends.
Combine Methods: For a comprehensive view of your progress, combine measurements with other metrics, such as progress photos and tracking how your clothes fit.
Use a Measurement Log: Write down your measurements, the date, and any relevant notes in a notebook or app. This allows you to track progress visually and numerically.

Frequently Asked Questions

You should always measure your waist while completely relaxed. Stand upright, breathe normally, and take the measurement after exhaling. Flexing or sucking in your stomach will give a false, smaller reading.

It is best to take your measurements in the morning, ideally before eating or exercising. Your body's size can fluctuate throughout the day due to factors like hydration, digestion, and muscle swelling after workouts.

Weekly or monthly measurements are sufficient for tracking long-term trends and progress. Taking daily measurements can be frustrating, as daily fluctuations are normal and not indicative of your overall progress.

As long as you are consistent with your chosen method, your measurements will be reliable for tracking your personal progress. Consistency is the most important factor for valid comparison over time.

Body measurements provide a more complete picture of body composition changes. The scale doesn't differentiate between fat loss and muscle gain, which can be discouraging, while measurements can show progress even if weight remains the same.

Yes, you can measure different body parts using different methods, as long as you are consistent with the chosen method for each specific body part. The consistency lies in your method for that single measurement, not for your entire body.

The most common mistake is inconsistency, such as measuring at different times of day, using inconsistent posture, or not measuring at the same location. These errors can make results unreliable and progress difficult to track.

Use clear anatomical landmarks, like the navel for your waist or the midpoint between the shoulder and elbow for your bicep. Some people even make a small, washable mark on their skin or use a log to describe the exact location.