How To Measure Armpit To Armpit For Accurate Garment Sizing
Measuring armpit to armpit, known in the apparel industry as the "pit-to-pit" measurement, is the most reliable method for determining the flat-lay chest width of a garment. This dimension represents the distance across the front of the item from the lowest point of one armhole seam to the other, providing a vital baseline for comparing a garment’s fit against your own body measurements or a well-fitting piece of clothing you already own.
Essential Preparation and Measuring Equipment Requirements
Achieving a professional-grade measurement requires minimal tools but extreme attention to physical positioning. The garment must be stabilized on a rigid, flat surface to prevent fabric distortion, which is the primary cause of sizing discrepancies in e-commerce and retail environments.
- Measuring Tools: A flexible fiberglass or plastic tailor’s tape measure is mandatory. Avoid metal construction tapes, as they do not contour to the fabric and lack the necessary flexibility for accurate garment-surface measurements.
- Surface Preparation: Utilize a hard, flat, level surface such as a wooden dining table or a hard floor. Do not perform this measurement on a bed or carpet, as the surface indentation will skew the width by pulling the fabric downward.
- Garment Conditioning: Ensure the item is clean, dry, and pressed. Wrinkles or bunching fabric can reduce the apparent width of the garment by up to a half-inch, leading to sizing inaccuracies.
- Time Benchmark: The process requires approximately 90 seconds per garment to ensure proper alignment and tension-free measurement.
Precise Workflow for Calculating Pit-to-Pit Dimensions
Standardizing your measurement technique is critical for consistency. Always follow the garment's natural structure rather than pulling it tight.
Step 1: Prepare the Garment Surface
Lay the garment perfectly flat on your chosen surface. Button all buttons or zip all zippers to ensure the garment sits in its natural, closed configuration. Smooth out the fabric with your hands, starting from the center and moving outward toward the side seams to eliminate air pockets and folds. Ensure the garment is face-up, with the front side oriented toward the ceiling.
Step 2: Locate the Primary Anchor Points
Identify the exact point where the sleeve seam meets the side seam of the garment. This is the "pit." On most shirts, this is the lowest point of the armscye (the armhole). If the garment has a drop-shoulder construction, locate the point where the sleeve attaches to the bodice, ensuring you are measuring the widest part of the torso rather than the shoulder seam.
Pro-Tip: If the garment has a bulky seam or an unusual hemline at the armhole, place a small pin at the lowest point of the armhole to ensure your tape measure starts at the exact same coordinate on both the left and right sides.
Step 3: Align the Tape Measure
Place the end of the tape measure (the zero mark) exactly at the base of the left armpit seam. Stretch the tape straight across the chest to the corresponding point on the right armpit seam. The tape must remain perfectly horizontal and parallel to the bottom hem of the shirt. If the tape sags or angles upward toward the shoulders, your measurement will be artificially small.
Warning: Never pull the fabric taut. The goal is to measure the garment in its "relaxed" state. Stretching the fabric—especially with blends containing spandex or elastane—will result in an inflated measurement that will cause the garment to feel too small when worn.
Step 4: Record the Quantitative Data
Read the measurement at the exact point where the tape hits the right armpit seam. Round your measurement to the nearest eighth of an inch or half-centimeter. For industry-standard apparel sizing, the measurement is typically recorded in inches. Document this number clearly, noting the garment's size tag and brand if you are building a personal size profile.
How to Measure Jackets & Find Your Best Fit
Garment Measurement Comparison Standards
When comparing your measurements to size charts, it is essential to distinguish between "body circumference" and "flat-lay width." The following table illustrates common discrepancies and how to interpret them for different garment types.
| Fabric Characteristic | Measurement Method | Interpretation |
|---|---|---|
| Rigid (100% Cotton) | Flat-Lay (Pit-to-Pit) | Double the value for chest circumference; 0-inch ease. |
| Stretchy (Spandex Blend) | Flat-Lay (Pit-to-Pit) | Double the value; subtract 1-2 inches for form-fit. |
| Heavy Outerwear | Flat-Lay (Pit-to-Pit) | Double the value; add 2-4 inches for layering room. |
| Oversized/Boxy Fit | Flat-Lay (Pit-to-Pit) | Double the value; consider the "drop" of the armhole. |
Troubleshooting Common Measurement Failures
Even with careful technique, external variables can impact the accuracy of your sizing data. Address these common failures to maintain data integrity.
- Root Cause: Fabric Distortion. If the garment is knit or jersey-based, it may have stretched out of shape due to improper storage.
- Actionable Fix: Lay the garment flat and allow it to rest for 30 minutes to regain its shape before measuring. If distortion persists, gently steam the garment to relax the fibers back to their original state.
- Root Cause: Asymmetrical Seams. Some mass-produced items are cut improperly, resulting in one armhole being lower than the other.
- Actionable Fix: Measure both sides independently and calculate the average. If the discrepancy exceeds one inch, the garment is physically flawed and should not be used as a sizing benchmark.
- Root Cause: Inconsistent Tape Tension. Applying too much pressure on the tape measure forces the fabric to bunch, leading to a "short" measurement.
- Actionable Fix: Use a self-retracting tailor's tape that features a locking mechanism. Lock the tape at the exact width of the chest, then gently place it over the garment to verify that it matches the distance between seams without causing fabric deflection.
Frequently Asked Questions
Does Pit-to-Pit measurement equal my chest circumference?
No, the pit-to-pit measurement is a flat-lay dimension that represents only half of the garment's circumference. To determine your chest circumference, you must multiply your pit-to-pit measurement by two.
Should I measure a shirt I already own or my own body?
It is significantly more accurate to measure a shirt you already own that fits you perfectly. Measuring your own body is difficult to do alone and often fails to account for the necessary "ease" or extra space required for a garment to be comfortable.
What is the difference between chest size and pit-to-pit?
Chest size typically refers to your body measurement taken around the fullest part of your torso, while pit-to-pit is a physical measurement of the garment itself. Garments always require "ease," which is the difference between the garment measurement and your body measurement, to ensure mobility.
How much extra room should I add to my pit-to-pit measurement?
For a standard fitted shirt, you typically want the garment to be 2 to 4 inches larger than your actual body chest circumference. If you prefer a loose or oversized look, you should aim for a pit-to-pit measurement that provides 6 or more inches of total ease.
Improve your online shopping accuracy and garment tailoring precision by mastering the pit-to-pit measurement technique today. Review your favorite pieces of clothing using this method to create a personal sizing profile that eliminates the guesswork from your next purchase.
