For most upholstery work, a heavy-duty bonded nylon or heavy-duty polyester thread is a solid choice. Both are designed for durability and thicker materials like leather, vinyl, and canvas.

• Bonded nylon: Popular for indoor furniture and leather because it’s strong and abrasion resistant. The bonding helps reduce fraying and skipped stitches.
• Heavy-duty polyester: A good pick for outdoor cushions and patio projects thanks to UV and moisture resistance.
• Clear monofilament nylon: Useful when you want stitches to blend in on trims or multi-color fabrics, though it’s typically better for topstitching than high-stress seams.

Look for common upholstery sizes (often labeled V-69/Tex 70) and match your needle and machine settings accordingly. Testing on scrap fabric can help dial in results.

Both materials can work well—it depends on where and how the piece will be used.

• Nylon: Known for strong, slightly stretchy stitches and excellent abrasion resistance. It’s often chosen for leather or vinyl and indoor furniture.
• Polyester: Favored for outdoor or sunny spaces because it typically handles UV exposure and moisture better than nylon.

If you’re repairing outdoor cushions or marine gear, polyester may be a practical option. For indoor seating or leather goods, many sewists prefer bonded nylon. In either case, check your machine’s capabilities, use the right needle size, and sew a test seam to see what performs best for your specific fabric stack.

Upholstery threads are often labeled by size systems like Tex or V. In general, a higher number means a thicker, stronger thread.

• Common choice: Many upholstery projects use sizes around V-69/Tex 70 because it balances strength with sewability on compatible machines.
• Heavier sizes (e.g., Tex 90+): Consider for extra-thick leather, multiple layers, or high-wear seams—if your machine and needle can handle it.
• Lighter sizes: Useful for finer fabrics or decorative topstitching where bulk is a concern.

Match needle size to thread (for example, larger needles for thicker threads), lengthen the stitch slightly, and always confirm your machine’s recommendations. A quick test on scrap can help fine-tune tension and stitch length.

Many home machines can sew with upholstery thread, but setup matters.

• Check your manual: Confirm supported thread sizes and recommended needles.
• Needle and size: Start with a fresh, larger needle suited for heavy thread (often 16/100–18/110 for sizes like Tex 70).
• Adjust settings: Lengthen your stitch (e.g., 3–4 mm) and fine-tune tension to avoid looping.
• Guide the fabric: A walking foot or nonstick foot can help feed thick or sticky materials.
• Spool handling: Large cones may feed better from a separate stand.

Sew slowly over bulky seams, and test on scrap layers first. This can help you find a setup that works smoothly for your specific fabric and thread combination.

Upholstery thread is engineered for heavier materials and higher stress seams.

• Fiber and finish: Often bonded nylon or heavy-duty polyester, with a coating that helps reduce fraying and abrasion.
• Thickness: Typically thicker (e.g., V-69/Tex 70 and up) than standard all-purpose thread, creating stronger seams.
• Durability: Designed to handle friction from leather, vinyl, and canvas; some options are rated for outdoor use.
• Machine setup: Usually requires larger needles and adjusted tension/stitch length.

By contrast, regular all-purpose thread is thinner and suited to apparel or light home projects. Choosing the right type can help your upholstery seams look cleaner and hold up better under everyday use.