Underarm Luxury Bags: Sizing and Proportion
An underarm bag is defined by five numbers: body height of 20-26 cm, an internal arm clearance of 22-26 cm, a strap drop of 15-20 cm, a gusset of 5-7 cm and a strap width of 12-18 mm. Get the clearance wrong and the bag cannot be carried at all, whatever else is right. This guide breaks the five numbers down first, then shows how they interact with proportion, hardware scale and the carrying method.
The Five Measurements That Define an Underarm Bag
An underarm silhouette is the hardest shape in the category to size, because it has to satisfy two bodies at once: the arm that carries it and the torso it sits against. Five numbers govern it, and the first of them is the one most tech packs omit entirely. Arm clearance is the internal distance around the strap, measured with the bag closed and empty. If it is too small the arm will not pass through; too large and the bag slides down the body instead of staying tucked in place.
The remaining four numbers are more forgiving but no less specific, and each of them is measurable on a finished first article with a tape and a square. Body height decides whether the piece reads as a small day bag or as an evening object. Strap drop decides where the bag sits against the torso. Gusset depth decides capacity and profile weight. Strap width decides whether the piece reads as refined or as utility, and at this scale a strap only 3 mm too wide will dominate the whole silhouette.
The one-line answer
- Specify the arm clearance first, at 22-26 cm internal, then the body height at 20-26 cm, the strap drop at 15-20 cm, the gusset at 5-7 cm and the strap width at 12-18 mm. Clearance is the number that decides whether the bag can be carried at all.
Arm Clearance: The Number Nobody Specifies
Arm clearance is measured as the internal circumference formed by the strap and the top of the body, with the bag closed and empty. Below 22 cm the arm will not pass through comfortably in a sleeve; above 26 cm the bag slides down towards the elbow and stops being an underarm piece at all. It is the single figure that separates an underarm bag from a short-shoulder bag, and it is almost never on a tech pack.
- Below 22 cm: the arm will not pass through comfortably, especially in a sleeve.
- 22-26 cm: the working band, measured with the bag closed and empty.
- Above 26 cm: the bag slides towards the elbow and stops being an underarm piece.
- Measure it on the first article, because a drawing will not tell you what it feels like.
Body Height and the Underarm Band
Underarm bodies sit lower and wider than a top handle body, because the piece is read against the torso rather than against the hand. A body height of 20-22 cm reads as an evening or occasion piece, 24-26 cm reads as a small day bag that carries a phone, a card case and sunglasses, and anything above 26 cm starts to compete with the shoulder bag already sitting in the same collection. Width follows at 26-34 cm, which puts the ratio in the 0.65-0.78 band.
20-22 cm
An evening or occasion reading, with a 5 cm gusset and the narrowest strap in the category.
24-26 cm
A small day bag that carries a phone, a card case and sunglasses comfortably.
Above 26 cm
Competes with the shoulder bag in the same collection, and usually loses that argument.
Width 26-34 cm
Puts the height-to-width ratio in the 0.65-0.78 band, which is where the shape reads correctly.
Strap Drop and Strap Width
Drop on an underarm piece is short by definition: 15-20 cm from the top of the strap to the top of the body, which is what holds the bag under the arm rather than on the shoulder. Strap width is the more delicate figure, because at this scale the strap is a large part of what the eye sees: 12-18 mm, with 15 mm the working default. Above 18 mm the strap reads as a shoulder strap and the piece loses its register.
- Strap drop
- 15-20 cm from the top of the strap to the top of the body
- Strap width
- 12-18 mm, with 15 mm the working default
- Arm clearance
- 22-26 cm internal, measured closed and empty
- Strap core
- 2 mm, against 3 mm on a full shoulder strap
- Adjustment
- usually fixed rather than adjustable, to keep the clearance stable
Gusset Depth at a Small Body
Gusset depth on an underarm piece runs 5-7 cm, and the band is narrow for a reason that only becomes obvious once the bag is carried. At 5 cm the piece is flat against the body and reads as an evening object. At 7 cm it bulges slightly under the arm, which is visible in profile from the front and is the most common complaint about an otherwise correctly proportioned underarm shape. Above 7 cm the bag stops sitting flat against the torso and starts pushing the arm away from the body, which a wearer notices within a minute and a designer only notices on a fit model.
- 5 cm: flat against the body, and the correct choice for an evening reading.
- 6 cm: the working default for a small day bag under the arm.
- 7 cm: the practical maximum before the piece bulges in front profile.
- Above 7 cm: the bag pushes the arm away from the body and stops sitting flat.
Handle vs Strap: Two Ways to Carry Under the Arm
Two constructions deliver an underarm carry, and they behave differently. A short fixed strap at a 15-20 cm drop carries the bag tucked under the arm, and the strap is usually fixed rather than adjustable so the clearance cannot drift. A rigid or semi-rigid handle at a 13-15 cm drop carries it in the crook of the arm, which reads as more formal and needs a firmer body to keep its shape against the torso.
- Fixed short strap: 15-20 cm drop, the clearance stays stable, and the read is relaxed.
- Rigid handle: 13-15 cm drop, needs a firmer body, and the read is formal.
- Adjustable strap: generally avoided here, because adjustment lets the clearance drift.
- Either way the anchor carries the whole load, so it is closed at 8-9 stitches per inch.
Proportion: The Ratio at Small Scale
Underarm shapes sit at the wide end of the accepted proportion band, and this is where most brands get the shape wrong by carrying a rule across from a different silhouette. A height-to-width ratio of 0.65-0.78 is correct here where it would read as a tray on a top handle piece, because a bag carried under the arm is seen in elevation against the torso and a wider shape sits flatter and reads as calmer. Below 0.6 it starts to look like a folder and above 0.82 it starts to look like a small shoulder bag, and in both cases the customer cannot say what is wrong, only that the piece does not look right.
How the Underarm Shape Fits a Collection
An underarm piece earns its place in a line by answering the one occasion neither a top handle bag nor a shoulder bag covers well: a short outing where the customer wants the bag out of the way but still in her hand. That makes it the natural fourth addition to a three-piece capsule, and the reason to hold it back from the first launch rather than include it and leave no room.
- Add it fourth, after a top handle piece, a shoulder bag and an evening piece.
- Keep it in the same leather family and the same hardware finish as the rest of the line.
- Scale the hardware down to 18 mm so it does not compete with the larger pieces.
- Offer it in a colour the customer would not choose in a larger size, because it is the second purchase.
- Specify it as a fixed strap, so the clearance cannot drift between runs or between sizes.
Tolerance Table for Underarm Proportions
The table below is the specification sheet we issue with an underarm first article. Each line is measurable and each line has a rejection threshold, so a brand can audit a shipment at AQL 2.5 (ISO 2859-1) without arguing about how the piece feels.
| Element | Specification | Tolerance | Failure threshold |
|---|---|---|---|
| Body height | 20-26 cm | plus or minus 3 mm | Outside the stated band |
| Arm clearance | 22-26 cm internal | plus or minus 5 mm | Below 22 or above 26 cm |
| Strap drop | 15-20 cm | plus or minus 3 mm | Outside the stated band |
| Strap width | 12-18 mm | plus or minus 1 mm | Above 18 mm on any unit |
| Gusset depth | 5-7 cm | plus or minus 2 mm | Above 7 cm in front profile |
| Ratio | 0.65-0.78 | Ratio check | Below 0.6 or above 0.82 |
| Stitch density | 8-9 stitches per inch | plus or minus 0.5 SPI | Below 7.5 or above 9.5 SPI |
| Hardware plating | 0.15-0.3 micrometres | plus or minus 0.02 micrometres | Failure at 24 h salt spray |
Sampling, MOQ and the Calendar
An underarm first article takes 6-10 working days from a confirmed tech pack, and 12-15 working days when the piece carries a semi-rigid handle or a blocked body, because the clearance has to be built and measured rather than estimated. Minimum order quantity is 500 pcs per style / colourway, bulk production runs 35-50 days from an approved sample, and every shipment is offered FOB Xiamen.
Our validated partner factory Quanzhou Yingming Bags has built underarm programmes since 2014 on 7 production lines with a monthly output of about 200,000 pcs, and specified programmes begin at USD 4.80 per unit. Every shipment is audited at AQL 2.5 (ISO 2859-1) on a sample pulled from the cartons, and the arm clearance is re-measured on that sample rather than trusted from the drawing.
Request an underarm proportion review
Send us a drawing and we will return the five numbers, a tolerance sheet and a costed specification within one working day. Start your underarm programme
Frequently Asked Questions
What is the correct drop for an underarm bag?
Fifteen to twenty centimetres from the top of the strap to the top of the body, which is what holds the bag under the arm rather than on the shoulder. Below 15 cm the bag rides into the armpit, and above 20 cm it becomes a short shoulder bag rather than an underarm piece.
How do you measure arm clearance on a bag?
As the internal circumference formed by the strap and the top of the body, measured with the bag closed and empty. The working band is 22-26 cm. Below 22 cm the arm will not pass through in a sleeve, and above 26 cm the bag slides towards the elbow.
What size should an underarm bag be?
A body height of 20-26 cm and a width of 26-34 cm, which puts the ratio in the 0.65-0.78 band. A 20-22 cm body reads as evening and a 24-26 cm body reads as a small day bag. Above 26 cm the piece competes with the shoulder bag in the same collection.
Why is my underarm bag sliding down my arm?
Because the clearance is too generous or the drop is too long. Above 26 cm of internal clearance the bag has nothing to hold it in place and it slides towards the elbow. Shortening the drop to 15-18 cm and fixing the strap rather than making it adjustable usually solves it.
Should an underarm strap be adjustable?
Usually not. An adjustable strap lets the clearance drift, and clearance is the figure that makes the bag work. A fixed strap at a 15-20 cm drop keeps the clearance where it was specified, which is why most underarm pieces in the category are built without adjustment.
How wide should an underarm strap be?
Twelve to eighteen millimetres, with 15 mm the working default. At this scale the strap is a large part of what the eye sees, so a strap only 3 mm too wide will dominate the silhouette. Above 18 mm the piece starts to read as a shoulder bag.
What gusset depth works on an underarm bag?
Five to seven centimetres. At 5 cm the piece sits flat against the body and reads as evening; at 7 cm it is at the practical maximum before it bulges in front profile. Above 7 cm the bag pushes the arm away from the torso and stops sitting flat.
Is an underarm bag structured or soft?
A semi-structured body is the usual answer, with a concealed base plate and a reinforcement tape at the stress points. A fully blocked frame is more than a bag carried against the torso needs, and a fully soft body collapses against the body instead of holding a shape.
What ratio is correct for an underarm silhouette?
Zero point six five to zero point seven eight, which is wider than the 0.75-0.85 band used on a top handle piece. A bag carried under the arm is seen in elevation against the torso, and a wider shape sits flatter and reads as calmer at that angle.
How long does it take to sample an underarm bag?
Six to ten working days from a confirmed tech pack, and twelve to fifteen working days when the piece carries a semi-rigid handle or a blocked body, because the clearance has to be built and physically measured. Bulk then runs 35-50 days from approval.
What is the minimum order quantity for an underarm programme?
Five hundred pieces per style and colourway. The threshold covers the body tooling, the hardware setup and the pattern planning, and it holds for a first capsule and for a reorder. Three colourways of one underarm shape are three qualifying runs.
How is the arm clearance checked before shipment?
A sample is pulled from the cartons and audited at AQL 2.5 (ISO 2859-1). The clearance is re-measured on that sample with the bag closed and empty, rather than trusted from the drawing, along with the body dimensions, the drop and the strap width.
Can an underarm bag also be worn crossbody?
Only with a second, longer strap, and it changes the specification. A crossbody strap at 50-60 cm on a 12-15 mm width is a separate carrying element with its own anchor, so the piece becomes a convertible style rather than a true underarm bag.
What hardware suits an underarm silhouette?
Small fittings, because the body is small. A closure scaled to 18 mm, a narrow strap end and feet sized to the base, all in one metal and one finish plated to 0.15-0.3 micrometres. Carrying medium hardware across unchanged is the most common mistake at this scale.
People Also Ask
What is an underarm bag?
A small bag carried tucked under the arm on a short fixed strap with a 15-20 cm drop and 22-26 cm of internal arm clearance. It sits against the torso rather than on the shoulder, which is why its proportions run wider and lower than a top handle piece.
How do I stop an underarm bag slipping?
Hold the internal clearance at 22-26 cm, keep the drop at 15-18 cm and use a fixed strap rather than an adjustable one. Slipping is almost always a clearance problem, and a drawing will not reveal it until the first article is built and measured.
What is the difference between an underarm and a shoulder bag?
Drop and clearance. An underarm bag runs a 15-20 cm drop on a 12-18 mm strap with 22-26 cm of clearance; a shoulder bag runs 25-30 cm on a 20-25 mm strap and needs no clearance figure at all.
How big should an underarm bag be?
A body height of 20-26 cm and a width of 26-34 cm, with a gusset of 5-7 cm. That carries a phone, a card case and sunglasses, sits flat against the torso and stays inside the 0.65-0.78 proportion band.
Are underarm bags structured?
Semi-structured is standard: a concealed base plate plus reinforcement tape at the stress points. A blocked frame is more rigidity than a bag carried against the body needs, and a fully soft body collapses instead of holding a shape.
Sources and further reading
Every figure on this page is either our own programme data or attributed below. Open the originals before you write them into a specification.
- ISO 2859-1 sampling procedures for inspection by attributesInternational Organization for Standardization The sampling standard behind the AQL 2.5 audit applied to underarm programmes.
- Business of Fashion industry reportingBusiness of Fashion Used to track how underarm proportions move between seasons.
- WWD accessories and handbag coverageWWD Referenced for how underarm silhouettes are merchandised alongside shoulder shapes.
- Leather Working Group audit protocolsLeather Working Group Referenced for traceability on the calfskin used in underarm programmes.
Five numbers decide whether an underarm bag works, and the clearance is the one that decides whether it can be carried at all. Specify all five before the first article is built, measure the clearance on the sample rather than trusting the drawing, and freeze the result on a tolerance sheet so the second run carries exactly like the first.
Send us a drawing and a target price band and we will return the five numbers, a tolerance sheet and a costed specification within one working day. Request an underarm proportion review