Quick answer: Use a flexible measuring tape to record your bust at its fullest point, your natural waist, and the fullest part of your hips and seat. Keep the tape flat and level without pulling it tight. Then compare all three numbers with the size chart for the exact dress—not your usual jeans or everyday dress size.
Only measure hollow-to-floor if the product guide asks for it. Instructions about shoes, bras, shapewear, and heel allowance differ, so follow the specific chart rather than a general rule. When you are ready to compare options, browse Selmori's prom dresses.
What you need before measuring
- A soft cloth or flexible plastic measuring tape
- A full-length mirror
- A friend or family member to help
- Your phone or paper for recording each result
- The size guide for the exact dress
- The undergarments specified by that guide
A rigid construction tape does not wrap around the body reliably. Measuring yourself is possible, but another person can more easily see whether the tape is level across your back.
Read the product size guide first
Do this before putting the tape around your body. Confirm whether the chart lists body measurements or the finished measurements of the garment. They are not interchangeable.
Also check:
- Does the chart use inches or centimeters?
- Is it specific to this product or only a general brand chart?
- Does it request bust, waist, and hips only?
- Does it also request hollow-to-floor?
- Should length be measured barefoot or in shoes?
- Does the seller add heel allowance separately?
- Does it specify a bra, shapewear, or another measuring layer?
Always use the chart and instructions attached to the dress you may actually order.
| Measurement | Where to place the tape | Common error to avoid |
|---|---|---|
| Bust | Around the fullest point, level across the back | Pulling the tape tight or measuring only the bra band |
| Natural waist | At the natural crease, with relaxed breathing | Using the waistband of everyday trousers as the location |
| Hips | Around the fullest part of hips and seat | Letting the tape angle upward or skipping the seat |
| Hollow-to-floor | From the hollow between the collarbones, following the seller's method | Adding shoes or heel allowance when the guide does not request it |
How to measure your bust
The bust measurement is not your bra band or cup size.
Stand naturally with your arms relaxed. Wrap the tape around the fullest part of your bust and across your back. Check in a mirror—or ask your helper to check—that the tape remains parallel to the floor.
The tape should lie flat without compressing the bust. Take a normal breath before reading the number; do not expand your chest or hold your breath.
Wear the bra or undergarment specified in the seller's instructions. If no guidance is given, use a close-fitting layer that creates a shape similar to what you expect under the dress. Avoid measuring over a sweater, loose shirt, or padded outer clothing.
How to find and measure your natural waist
Your natural waist may not be where the waistband of your jeans sits.
To find it, bend gently to one side. The crease that forms is usually your natural waist. It is often the narrowest part of the torso, but use the bend point rather than guessing from your belly button.
Tie a narrow ribbon or piece of elastic around that point if it helps you keep the location consistent. Stand upright, place the measuring tape over the ribbon, and keep it horizontal around the body.
Let your stomach rest naturally. Do not suck in, push out, or pull the tape tighter to reach a preferred number. You should be able to breathe normally while the tape lies flat.
How to measure your hips
For a prom dress, the hip measurement includes the fullest part of your hips and seat.
Stand with your feet together. Wrap the tape around the widest circumference and keep it parallel to the floor.
The fullest point may be lower than expected. Slide the tape slightly up and down, then use the largest accurate reading rather than measuring only across the front of the hip bones.
Turn sideways in a mirror to check that the tape is not rising at the back. A helper is especially useful here.
When to measure hollow-to-floor
Hollow-to-floor is a length measurement, not one of the three main body circumferences. Measure it only if the product page, size chart, or seller specifically requests it.
The “hollow” is the small indentation at the center base of your neck, between the collarbones. A helper holds the beginning of the tape there and measures straight down the front of the body to the floor, following the seller's stated method.
Do not substitute your total height. Hollow-to-floor starts at the neck, so two people of the same height can have different measurements. Do not substitute hollow-to-hem either; that measurement stops at the intended dress hem and may be requested for a shorter style.
Should you wear prom shoes?
Follow the seller's instructions exactly. Some guides ask you to wear the intended shoes or an equivalent heel height. Others request a barefoot hollow-to-floor measurement and add heel allowance separately.
Mixing the two methods can produce the wrong length. Record which method you used and the heel height, even if the chart does not ask you to submit it.
The same principle applies to undergarments. Use what the specific guide requests rather than assuming every prom dress should be measured in the same bra or shapewear.
Compare your measurements with the size chart
Write your bust, waist, and hip measurements beside the corresponding rows or columns in the product chart.
Each measurement may point to a different size. That is normal. Do not average the three numbers; an average can hide the area that actually needs room.
Do not choose based only on your usual clothing size. Formalwear brands use different patterns, and even two dresses from the same retailer may have different fit notes.
What if you are between two sizes?
First, follow any between-size instruction provided with the product.
If the seller gives no direction, a common starting point is the size that accommodates your largest measurement. That often means considering the larger size because taking in certain areas may be more feasible than creating room where little seam allowance exists.
This is not a promise that every dress can be altered. Boning, beading, lace placement, seams, lining, and stretch can change what is possible.
Contact the retailer or an experienced alterations professional before ordering if:
- Your measurements span several sizes
- The dress is closely fitted through the hips
- The bodice is heavily structured or embellished
- You are relying on a future alteration
- The product description and size chart seem inconsistent
Never size down solely because you plan to lose weight before prom.
Common measuring mistakes
- Using bra size instead of measuring the fullest bust
- Measuring the jeans waistband instead of the natural waist
- Measuring only the front of the hips
- Missing the fullest part of the seat
- Letting the tape slope or twist
- Pulling the tape tightly into the body
- Holding your breath or changing your posture
- Measuring over bulky clothing
- Switching undergarments between attempts
- Using another brand's size chart
- Mixing inches and centimeters
- Rounding a measurement down
- Ignoring the seller's shoe instructions for length
- Reusing old measurements without checking them
Use this prom dress measuring checklist
Before measuring
- Open the exact product size chart.
- Confirm body versus garment measurements.
- Confirm inches or centimeters.
- Read the undergarment, shoe, and length instructions.
- Ask someone to help and stand naturally in front of a mirror.
Measurements
- Bust taken at the fullest point, with the tape level across the back.
- Natural waist found with the side-bend test and measured without holding in the stomach.
- Hips measured around the fullest part of the hips and seat, with feet together.
- Hollow-to-floor measured only if requested.
- Shoe method and heel height recorded when relevant.
Record and verify
Write down the date, product name and URL, chart unit, measuring undergarments, each body measurement, the shoe method, and the size indicated by each chart row.
Take every main measurement twice from a fresh tape position. If two readings differ, reset your posture and take a third rather than averaging blindly. Keep the original numbers and never round down to fit a smaller chart row.
Final check before ordering
Measure first, choose the dress second, and read the exact chart again before checkout. Allow time to ask questions and assess whether alterations may be needed.
Our guide to when to buy a prom dress can help you plan shopping, delivery, and fitting time. The same measuring routine can help when comparing formal evening dresses, but reopen the product-specific chart each time.
Frequently asked questions
What measurements do I need for a prom dress?
Most standard prom dress charts use bust, natural waist, and hips. Some sellers also request hollow-to-floor or another length measurement. Provide only the measurements requested for the specific dress.
Can I measure myself?
Yes, but a helper is preferable. It is difficult to keep the tape level across your back while also reading it. Hollow-to-floor is particularly hard to measure accurately alone.
Should I wear a bra while measuring?
Follow the product's instructions. If a bra or shapewear is specified, use the type you expect to wear with the dress. Do not assume one undergarment rule applies to every neckline or bodice.
Should I wear shoes for hollow-to-floor?
Only if the seller says to. Some sellers measure with shoes, while others request a barefoot measurement and account for heel height separately. Never combine the two methods.
What if my bust, waist, and hips indicate different sizes?
Do not average them. Follow the product instructions and pay attention to the largest measurement. If the chart does not explain what to do, ask before ordering, especially for a fitted or structured dress.
Is hollow-to-floor the same as height?
No. Height runs from the top of the head to the floor. Hollow-to-floor begins at the indentation between the collarbones and measures down according to the seller's method.
The bottom line
Accurate prom dress measurements begin with the exact product guide. Measure the fullest bust, natural waist, and fullest hips with a level, comfortably close tape. Add hollow-to-floor only when requested, follow the stated shoe method, record each attempt, and compare every number instead of trusting an everyday size label.
Editorial note: This guide reflects current body-measurement guidance from retailer and university extension sources reviewed September 6, 2026. A size chart estimates fit; it cannot replace trying on the actual garment or advice from a qualified alterations professional.
Further reading
The University of Tennessee Extension guide to shopping for clothes online provides additional measurement and fit context. Always return to the size chart for the exact Selmori dress before ordering.