Best leather thread for hand stitching
Thread is the cheapest component of a seam and the most visible. One spool of the right diameter outlasts a dozen impulse buys of the wrong one.
Quick answer
Buy Ritza 25 “Tiger” thread in 0.6 mm for your first spool — flat-braided, pre-waxed polyester that lies neat, rarely frays, and matches the 3.85 mm irons most beginners own. Add 0.8 mm when you start bags and straps. Choose waxed linen (Fil au Chinois lin cable 432/532) when you want the traditional matte look and are willing to trade some durability for it.
Hand-stitching thread comes down to two families. Braided polyester (Ritza 25 is the benchmark) is interlaced so it cannot untwist as you sew, comes lightly pre-waxed, shrugs off UV and abrasion, and its flat profile settles flush into the stitch groove. Twisted waxed linen (Fil au Chinois lin cable is the classic) is the heritage option — matte, warm, takes burnishing beautifully, and ages the way old saddlery does — but it is fuzzier, weaker size-for-size, and wants occasional re-waxing.
Whichever fibre you choose, diameter beats brand: the thread must fill the hole your irons make without bulging it. Run your pitch through the stitch pitch converter or the needle & thread selector before buying.
The sizes that actually matter
Ritza 25 is sold in 0.6, 0.8, 1.0 and 1.2 mm (plus rare 1.4/1.7 mm), on 25 m/100 m mini spools or 500 m rolls. Those four diameters map cleanly onto stitch pitch:
Hand-stitching diameters at 10×
Match diameter to pitch first: 0.6 mm for 3.85 mm irons is the classic beginner pairing.
Ritza 25 “Tiger”: why it became the default
Julius Koch’s Ritza 25 earned its reputation on three habits beginners appreciate: the braid never unravels mid-seam, the light factory wax means it grips each stitch without gumming your needles, and the flat ribbon-like profile makes even slightly uneven tension look tidy. Polyester also melts, so you can finish ends with a lighter tap instead of knots.
Needle pairing (per Rocky Mountain Leather Supply): 0.6 mm → John James size 2 or 4; 0.8 mm → size 2 or 1/0; 1.0 mm → 1/0 or 2/0; 1.2 mm → 2/0 or 3/0. Two needles per seam for the saddle stitch.
Waxed linen: the heritage pick
Fil au Chinois lin cable is twisted, assembled, moistened, waxed and re-twisted (“cabling”) into a dense round thread. The common sizes on 50 g spools: 332 (0.77 mm, the thickest), 432 (0.63 mm), 532 (0.57 mm), 632 (0.51 mm) and 832 (0.43 mm, the finest). 432 and 532 cover most wallet and small-goods work.
Linen’s appeal is the matte, slightly irregular, deeply traditional look — and how it takes beeswax. Its costs: lower strength than polyester at the same diameter, fuzz that wants re-waxing on long seams, and less abrasion resistance on hard-use items. Full comparison: polyester vs linen thread.
Tex numbers, decoded once
Machine threads are sized in Tex — the weight in grams of 1,000 m of thread, so higher = thicker. Ticket numbers like #69/#138 are brand conventions (V69 ≈ Tex 70, V138 ≈ Tex 135). Rough map: Tex 70 is the ceiling for domestic machines and suits wallets; Tex 135 covers bags on industrial machines; Tex 207–415 is belt/holster territory for heavy stitchers. Hand-stitching sizes sit far above domestic machine range — another reason hand vs machine is not a straight swap.
One warning that saves sewing machines: never run waxed hand thread through a machine — wax gums the tension discs. Machines want bonded nylon or polyester.
Threads worth buying
One 0.6 mm spool starts you; 0.8 mm joins when bags do.
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Waxed Polyester Thread 0.45 mm (Fine)
- Size
- 0.45 mm | ~180 m spool
- Pitch
- 2.7 mm
- Thread
- 0.45 mm
- Material
- Polyester
- Weight
- 2-4 oz
- Level
- Beginner
Braided, pre-waxed polyester in a fine diameter for tight pitches. Comparable to Meisi 0.45.
Reviewed 2026-06-30 -
Waxed Polyester Thread 0.55 mm (Fine-Medium)
- Size
- 0.55 mm | ~160 m spool
- Pitch
- 3.2 mm
- Thread
- 0.55 mm
- Material
- Polyester
- Weight
- 2-5 oz
- Level
- Beginner
Steps up from 0.45 mm for card holders and slim wallets stitched with 3.0–3.38 mm irons.
Reviewed 2026-06-30 -
Ritza 25 Tiger Thread 0.6 mm
- Size
- 0.6 mm | 25 m or 500 m
- Pitch
- 3.85 mm
- Thread
- 0.6 mm
- Material
- Polyester
- Weight
- 3-7 oz
- Level
- Beginner
The default beginner thread — flat, pre-waxed polyester that lies neat and rarely frays. Great for wallets and small bags.
Reviewed 2026-06-30 -
Ritza 25 Tiger Thread 0.8 mm
- Size
- 0.8 mm | 25 m or 500 m
- Pitch
- 4.5 mm
- Thread
- 0.8 mm
- Material
- Polyester
- Weight
- 5-10 oz
- Level
- Beginner
Heavier flat polyester for bags, totes and straps stitched at 4.0–4.5 mm. Bold but still refined.
Reviewed 2026-06-30 -
Waxed Polyester Thread 1.0 mm (Heavy)
- Size
- 1.0 mm | ~100 m spool
- Pitch
- 5 mm
- Thread
- 1 mm
- Material
- Polyester
- Weight
- 8-12 oz
- Level
- Beginner
Thick thread for belts and heavy totes. Match to 5.0 mm spacing for a rugged, even stitch.
Reviewed 2026-06-30 -
Waxed Polyester Thread 1.2 mm (Heavy Duty)
- Size
- 1.2 mm | ~90 m spool
- Pitch
- 6 mm
- Thread
- 1.2 mm
- Material
- Polyester
- Weight
- 8-14 oz
- Level
- Beginner
The heaviest common hand-stitch diameter. Use for 6 mm spacing and rugged goods; too bulky for wallets.
Reviewed 2026-06-30 -
Linen Thread 18/3 (approx 0.55 mm)
- Size
- 18/3 waxed linen | ~50 m
- Pitch
- 3.38 mm
- Thread
- 0.55 mm
- Material
- Linen
- Weight
- 2-6 oz
- Level
- Intermediate
Traditional waxed linen for a matte, classic look. Needs re-waxing and is fuzzier than polyester but ages beautifully.
Reviewed 2026-06-30 -
Linen Thread 18/5 (approx 0.8 mm)
- Size
- 18/5 waxed linen | ~50 m
- Pitch
- 4.5 mm
- Thread
- 0.8 mm
- Material
- Linen
- Weight
- 5-10 oz
- Level
- Intermediate
Heavier linen for bags and belts. Choose linen for restoration and heritage work; polyester for durability and ease.
Reviewed 2026-06-30
Key takeaways
- First spool: Ritza 25 Tiger, 0.6 mm, in a neutral colour.
- Braided polyester = durable and tidy; twisted linen = traditional and matte.
- Diameter beats brand — fill the hole, don’t bulge it.
- Waxed thread is for hands only; machines take bonded, unwaxed thread.
Reading in order? Continue with polyester vs linen thread for leather; the previous chapter was saddle stitch thread size chart.
Frequently asked questions
What thread size for 3.85 mm stitching chisels?
0.6 mm is the classic pairing (Ritza 25 0.6 or linen around 532/432). Step to 0.8 mm on bags where you want a bolder line.
Is Tiger thread the same as Ritza 25?
Yes — “Tiger” is the nickname for Julius Koch’s Ritza 25 braided polyester. Beware “tiger-style” listings of unknown origin; the braid quality is the whole point.
How much thread do I need for a seam?
Cut about four times the seam length (4.5× over 8 oz of stack), plus ~8 in for tails. Or skip the arithmetic and use the thread length calculator.
Polyester or linen for a first project?
Polyester. It forgives uneven tension, doesn’t fray while you learn, and costs less per metre. Come back to linen when the look matters more than the learning curve.
What do Tex 70 and #69 mean on machine thread?
Tex is grams per 1,000 m (bigger = thicker); #69 is the ticket name for roughly Tex 70 bonded nylon — the heaviest most domestic machines handle.