Quick answer: Square-bottom bags (SOS) stand upright and carry handles — they serve retail, grocery and food delivery, and run on VFD square-bottom lines at up to 200 bags/min. V-bottom bags (side gusset) are lighter, faster and cheaper per bag — they serve bakery, snacks and Produce, and run on VJD V-bottom lines at up to 500 bags/min. Choose by the bag your market buys, not by machine price.
Most buyers start with the machine. Start with the bag instead: who carries it, how heavy it is, and whether it must stand on a shelf. Everything else — paper width, GSM range, handle system, budget — follows from that answer.
The two bag styles, in one paragraph
A square-bottom bag (also called SOS, block bottom or satchel) has a flat rectangular base, so it stands upright, holds volume, and takes twisted, flat or patch handles. It is the standard grocery and retail carrier. A V-bottom bag (also called side-gusset or satchel-bottom) folds flat, has no separate base, and is the classic bakery, sandwich and snack bag. One stands like a box; the other packs like an envelope.
Where square bottom wins
Choose square bottom when the bag must:
- Stand upright on a counter or shelf — takeaway food, retail carriers, liquor bottles
- Carry handles — twisted rope, flat paper or patch handles, applied inline
- Hold serious weight — heavier kraft GSM, reinforced base
The VFD square-bottom series covers bag widths from 80 mm to 460 mm, paper roll widths from 320 mm to 1300 mm, and runs 50–150 GSM kraft at up to 200 bags/min on the standard models (VFD-190/290/330/460). The economy F-series (VFD-220F/280F/330F/450F) trades top speed for a lower entry point, running 30–200 bags/min on 50–160 GSM paper. For retail carriers, inline handle units (VFD-T for twisted rope, VFD-AF for flat handles) apply handles without taking the bags off the line.
Where V bottom wins
Choose V bottom when the bag is:
- Light and flat-packed — bakery bags, sandwich bags, snack pouches, produce bags
- High volume, low margin — speed and paper economy decide profit
- Handle-free — no handle unit to buy, run or maintain
The VJD V-bottom series runs 35–80 GSM paper — roughly half the GSM of a typical carrier bag — which is where the per-bag cost advantage comes from. Servo models (VJD-400/650/850) cover 70–350 mm bag widths; the high-speed VJD-270 and VJD-350 (seven-servo drives) reach 500 bags/min. Mechanical VJD-M models (VJD-420M/650M/850M) run 60–500 bags/min on 6–7.5 kW — a simpler drive train for markets that value easy local servicing.
Side-by-side
| Square bottom (VFD series) | V bottom (VJD series) | |
|---|---|---|
| Typical use | Retail carrier, grocery, takeaway | Bakery, snacks, produce |
| Stands upright | Yes | No |
| Handles | Twisted / flat / patch, inline options | None |
| Paper GSM | 50–160 | 35–80 |
| Max speed | up to 200 bags/min | up to 500 bags/min |
| Bag width range | 80–460 mm | 70–350 mm |
| Drive | Servo standard; economy F-series available | Servo, high-speed 7-servo, or mechanical |
Three questions that decide it
- Does the bag need to stand and carry? Yes → square bottom. No → V bottom.
- What GSM will you run? Above ~90 GSM you are in square-bottom territory; below ~80 GSM, V bottom.
- What does your local market already sell? The fastest path to ROI is entering an existing demand curve, not educating one — see our paper bag ROI guide for the four numbers to check before committing.
FAQ
Can one machine make both bag styles?
No — the forming units are fundamentally different. Many buyers start with one line and add the second as their customer base expands.
Which line is cheaper to operate?
V bottom uses less paper per bag and runs faster, so the per-bag cost is lower. Square bottom commands a higher bag price in retail, which is where its margin comes from.
What about handles on square bottom bags?
Handles can be applied inline (VFD-T / VFD-AF) or off-line with a separate handle-making machine feeding finished bags.
What is the lead time?
Lead times run 7–45 days depending on the machine; every shipment includes a 2-year warranty and lifetime technical support.
Next steps
Compare machine types in detail in our paper bag machine types guide, walk the full production line process, or go straight to the paper bag machine buying guide for models, features and selection checklists.