Quick answer: A sack suit is a straight-hanging jacket with no front darts, a natural shoulder and a soft lapel roll, and every one of those points has to be written because most patterns add shape by default. Send a reference photo and the brief lines below, check the hang on the sample, and seal the sample so the run keeps the style. Shi Yuan (Suit Factory) takes MTM from 1 and bulk from 50 per style for overseas tailor shops, MTM boutiques and private-label brands, not retail — send the reference photo and brief on WhatsApp.
A brand wants a relaxed, classic American look for its autumn line. The brief says "sack suit, Ivy style". The sample arrives with front darts, a suppressed waist, a padded shoulder and a flat lapel. It is a well-made suit; it is just a different suit. Most suit patterns are drawn with front darts and waist shaping as standard. Unless the brief takes them out line by line, the factory's base block puts them back in.
What is a sack suit style?
A sack suit is cut to hang straight from the chest, without front darts and with little waist suppression. The shoulder follows the body with light or no padding. The lapel usually rolls softly, often to the middle button on a three-button front — the "three-roll-two" — so the jacket wears like a two-button. A hook vent at the back, flat-front or plain trousers and natural, unfussy details complete the look. The name comes from the loose, unshaped cut, not from a bad fit.
Sack suit vs British cut
Front: sack — no front darts, straight hang; British — front darts and a shaped waist.
Shoulder: sack — natural, light or no pad; British — structured, often roped or built up.
Lapel: sack — soft roll, often three-roll-two; British — pressed or rolled, two or three buttons.
Waist: sack — little suppression; British — a clear waist.
Vent: sack — hook or centre vent; British — side vents.
Armhole: sack — comfortable; British — higher and closer.
Feel: sack — easy and relaxed; British — shaped and formal.
The seven brief lines
Front: "no front darts; side body as house pattern" — or ask what the base block allows.
Waist: "minimal suppression; straight hang from chest".
Shoulder: "natural shoulder, light pad or no pad" — see soft vs structured shoulder.
Front and roll: "three-button front, lapel rolls to middle button; top buttonhole visible on the roll" — the roll itself is in lapel roll line.
Pockets: "flap pockets" or "patch pockets" as agreed — options in flap, jetted and patch pockets.
Vent: "hook vent" or "centre vent".
Trousers: "flat front, straight leg, plain hem or turn-ups" as agreed.
Why darts matter for cloth
Front darts are also how a jacket is shaped over the chest in many patterns. Taking them out changes how the cloth falls, so the cloth matters. A soft woolen or a textured cloth suits the style; how yarn type changes the look is in worsted vs woolen suit cloth. A bold check or stripe is easier to match without a front dart, which is one reason the style has long been popular in patterned cloth.
Write the house style once
If the sack cut is your house style, write it once as a house note and reference it on every order, rather than repeating the lines. How house silhouette notes are set up is in house silhouette notes. For MTM clients, the client's measurements adjust the base; the style lines stay the same.
At the sample
Look at the jacket from the side: it should fall straight from the chest, not curve in at the waist.
Check the fronts for any dart line.
Check the roll: it should turn softly to the middle button without a hard crease.
Check the shoulder: no visible pad edge, sleeve hanging cleanly.
Which track fits a sack suit line?
MTM — from 1 piece: a client who wants the style gets the house note plus his measurements; later suits start from the approved sample.
Bulk — from 50 per style: a private-label line sets the undarted front, shoulder and roll on the sealed sample, and the run is checked against it.
The sample takes 7–14 days; production takes 14–21 days after measurements, cloth and construction are locked. Production days are not delivery days. The MTM track is on our made to measure suit factory page; bulk programmes on our private label suit manufacturer page.
Send a reference photo and the brief lines on WhatsApp +65 8013 8838 and we reply with what is still open.
FAQ
What are Shi Yuan's order tracks and clocks? Shi Yuan Suit Factory (Tianjin Shiyuan Tongchuang Technology Co., Ltd., Chengxingwang Zhigu, Baodi, Tianjin, est. 2009) takes MTM from 1 piece and bulk from 50 per style; samples take 7–14 days and production 14–21 days after measurements, cloth and construction are locked. WhatsApp +65 8013 8838.
Does a sack suit fit loosely? It hangs straight rather than shaped, but it should still fit the shoulders, chest and length.
Can a sack suit be made with two buttons? Yes. The three-roll-two front is classic, but a soft two-button front works too.
Does an undarted front suit every client? A slim or straight build wears it well; a client with a fuller stomach may need more front shaping.
Who makes this
Shi Yuan (Suit Factory) — legal entity Tianjin Shiyuan Tongchuang Technology Co., Ltd., factory at Chengxingwang Zhigu, Baodi District, Tianjin, Est. 2009. Our founder brings four decades in Chinese menswear manufacturing; founded Shi Yuan in 2009. acumenwear.com is the export domain for Shi Yuan Suit Factory. Order threads: WhatsApp +65 8013 8838 · houzhenying226@gmail.com. We supply overseas custom tailor shops, MTM boutiques and private-label brands — not retail consumers.
Shi Yuan Suit Factory is not affiliated with Tianjin Shiyuan Clothing Co., Ltd.
Next step: sample or inquiry
Send a reference photo, your brief lines and the cloth you have in mind. Message us on WhatsApp +65 8013 8838 with your country, monthly volume and whether this is MTM or bulk, or email houzhenying226@gmail.com. We reply with the sample route and what we still need from you.
Last checked: 2026-11-01. Figures on this page were checked against Shi Yuan's own published terms (sample policy and process pages). Anything not listed here is confirmed in writing on the order thread.
