Raw Denim Sizing Guide: How to Get the Perfect Fit on Shrink-to-Fit Selvedge (2026)
To size raw denim correctly, buy sanforized (one-wash) jeans true to your measured waist, and size up about 1 inch on unsanforized (shrink-to-fit) selvedge to allow for roughly 5–10% shrinkage after the first soak.
At Japan-Denim.com, sizing is the single most common reason a first pair of raw selvedge disappoints — and the easiest mistake to avoid. This guide explains how raw denim sizing works, why shrinkage matters, how to measure yourself accurately, and exactly how much to size up depending on the fabric.
What Is Raw Denim Sizing?
Raw denim is unwashed denim that has not been pre-shrunk or distorted at the factory. Because of this, the fit you get out of the box is not the fit you'll keep. Raw denim falls into two categories that size very differently:
Sanforized (one-wash) denim has been mechanically pre-shrunk, so it shrinks very little — usually 1–3% — after you wash it. You generally buy it true to your measured waist.
Unsanforized (shrink-to-fit, or STF) denim is sold loomstate and will shrink noticeably — often 5–10% in the waist and inseam — after its first hot soak or wash. With unsanforized selvedge, you intentionally size up so the jeans shrink down to your target measurements.
History and Background
Shrink-to-fit sizing dates back to the original Levi's 501, which was sold unsanforized for decades. Buyers were expected to soak the jeans, let them shrink, and mold them to the body. Sanforization — a pre-shrinking process patented by Sanford Cluett in 1930 — made jeans more predictable and became the mass-market standard.
Japanese selvedge brands from Okayama and Osaka deliberately kept both traditions alive. Many purist makers — such as Momotaro, The Strike Gold, and certain Iron Heart runs — offer unsanforized denim precisely because the soak-and-shrink ritual produces a more personalized fit and honest, vertical fades. That authenticity is part of what US and Canadian enthusiasts pay a premium for.
Deep Dive: How to Size Raw Denim the Right Way
The reliable method is to measure, not guess. Find a pair of pants that already fit you well and lay them flat. Measure four points: waist (across the top, doubled), front rise, thigh, and inseam. These are your target post-shrink measurements.
Next, check the brand's size chart, which almost always lists measurements in two states: raw/pre-shrink and post-wash. Match the post-wash numbers to your targets — not the raw numbers. This single habit eliminates most sizing errors.
General rules by fabric type:
- Sanforized (one-wash): Buy true to your measured waist. Expect ~1–3% shrinkage, mostly in the inseam.
- Unsanforized (shrink-to-fit): Size up about 1 inch in the waist (roughly one tag size) and expect 5–10% shrinkage. Heavier weights (16oz+) can shrink more.
- Inseam: Always buy long on unsanforized denim — inseams can lose 1.5–3 inches after a hot soak.
Remember that raw denim also stretches back out with wear. A snug-but-not-painful waist on day one will relax about half an inch within a week, so resist sizing too large for comfort.
Best Options: Our Top Picks by Sizing Type
Best One-Wash (Easy Sizing): Japan Blue / Iron Heart Sanforized
- Best for: First-time raw denim buyers who want predictable fit.
- Key specs: Sanforized 14–18oz selvedge, ~1–3% shrinkage.
- Price range: $185–$350 USD.
- Why we recommend it: Buy true to size and skip the soak math — ideal for getting your first fit right.
Best Shrink-to-Fit (Traditional): Momotaro Unsanforized
- Best for: Purists who want a custom, soak-molded fit.
- Key specs: Unsanforized 15.7oz+ selvedge, 5–10% shrinkage.
- Price range: $300–$450 USD.
- Why we recommend it: Sizing up about 1 inch yields the most personalized, authentic fit available.
Best Heavyweight (Plan for Shrink): The Strike Gold / Samurai 18–21oz
- Best for: Experienced wearers chasing dramatic fades.
- Key specs: Heavy unsanforized selvedge, higher shrinkage potential.
- Price range: $280–$420 USD.
- Why we recommend it: Big fabric and big fades — just account for extra inseam shrinkage.
| Fabric Type | Typical Shrinkage | How to Size | Inseam Tip |
|---|---|---|---|
| Sanforized (one-wash) | 1–3% | True to measured waist | Buy near target length |
| Unsanforized (shrink-to-fit) | 5–10% | Size up ~1 inch | Add 1.5–3 inches |
| Heavyweight unsanforized (18oz+) | 7–12% | Size up ~1 inch+ | Add up to 3 inches |
Frequently Asked Questions
Q: How much should I size up in raw denim?
A: For unsanforized (shrink-to-fit) raw denim, size up about 1 inch in the waist to allow for 5–10% shrinkage after the first hot soak. For sanforized (one-wash) denim, buy true to your measured waist.
Q: How do I know if my raw denim is sanforized or unsanforized?
A: Check the product description or size chart. Sanforized denim is labeled "one-wash" or "pre-shrunk" and shrinks 1–3%, while unsanforized denim is labeled "loomstate" or "shrink-to-fit" and shrinks 5–10%.
Q: How much does raw denim shrink?
A: Sanforized raw denim shrinks about 1–3%, while unsanforized shrink-to-fit denim shrinks roughly 5–10%, with heavier weights above 18oz sometimes shrinking up to 12%.
Q: Should raw denim fit tight at first?
A: Yes, slightly. Raw denim stretches back out about half an inch in the waist within the first week of wear, so a snug but comfortable fit on day one will relax into the ideal fit.
Q: Does raw denim shrink in the waist or the length?
A: Both, but the inseam usually shrinks most — often 1.5–3 inches on unsanforized denim — so always buy extra length when choosing shrink-to-fit selvedge.
Q: Can I avoid shrinkage by not washing my raw denim?
A: Delaying the first wash postpones shrinkage but does not prevent it; the fabric will still shrink when it eventually gets wet, so size for the post-wash measurements from the start.
The Bottom Line
Sizing raw denim is simple once you know the fabric: buy sanforized true to size, and size up about 1 inch on unsanforized shrink-to-fit selvedge while always favoring extra inseam length. Match your measurements to the brand's post-wash chart, and your first pair will fit the way it should after settling in.
At Japan-Denim.com, we list shrinkage behavior and post-wash measurements for the Japanese selvedge we curate, so US and Canadian buyers can order with confidence. Explore our guides below to dial in fit, care, and fades on your next pair.
