Sake Guide Lesson 3: What Is Rice Polishing Ratio?

Each step in the sake-brewing process is critical to sake production, but rice polishing in particular garners a lot of attention due to its influence on sake categorization and pricing. Rice polishing is the process by which the outer layers of a grain of rice (the bran) are polished or milled away. Here, we discuss the purpose of rice polishing, how it’s done and its effects on the categorization and flavor profiles of sake.

What is the purpose of rice polishing?

Simply put, “seimaibuai” (rice polishing ratio) is a description of the percentage of grain that remains after a part of the rice has been polished away. For example, sake with 60% RPR means that about 40% of the rice’s outer layer has been milled away. You can usually find a sake’s rice polishing percentage on its label.

Why is rice polishing necessary? It shaves away protein and fat, leaving the starchy interior (“shimpaku”) used in saccharification (the conversion of starch to sugar), which is necessary to brew alcohol. Brewers determine the level of rice polishing and gently mill away these elements to achieve the desired taste profile of the final product. The more that the outer bran is milled away, the cleaner and more delicate the final sake tastes. Conversely, some brewers leave the majority of the grain intact when they wish to convey more robust, earthy flavor profiles. There is a vast spectrum of rice polishing, from extreme rice polishing of just 1% to sake that is barely polished, like Hara Brewing Company’s Koshi no Homare “90” series. Many brewers make products with different rice polishing ratios under the same brand to cater to different preferences and occasions.

How is sake rice polished?

During the Edo period (1603-1868), grinding machines manually powered by foot pedaling were used to mill and polish rice. Not only was this extremely laborious for the workers, but it was also inefficient in terms of production volume and rice quality; the polishing wasn’t even, and grains were more prone to breakage, which would render a decent portion unusable. After that, brewers switched from human-powered methods to the water wheel. These days, breweries use vertical rice polishing machines that are very precise and automated, ensuring greater uniformity, less breakage and the ability to polish to a greater degree.

Categorization of sake

Rice polishing ratio and brewing method are factors in determining the sake category. Another factor is the ratio of ingredients, like koji and brewer’s alcohol (if added). When it comes to premium sake (“tokutei meishoshu”), there is only one category that does not have a set RPR: junmai. Aside from that, the RPR for honjozo sake must be at least 70%; tokubetsu (“special”) honjozo, tokubetsu junmai, junmai ginjo and ginjo at least 60%; and junmai daiginjo and daiginjo at least 50%. “Futsushu,” or table sake, does not have a set polishing ratio.

Generally speaking, the more polished rice becomes, the more expensive the final product will be due to smaller yields, as well as the work required for such significant milling. Highly polished styles like ginjo and daiginjo typically have fruity aromas, light body and cleaner flavors. The focus on ginjo-style sake is relatively new, as a result of the lifting of taxes on sake with higher rice polishing ratios and the new consumer demand for refined products.

Rice polishing ratios in sake: seven product examples

Tasting sake of different rice polishing ratios is the best way to acquaint yourself with how these numbers affect flavor. Here are examples of sake from various categories and how RPR factors into their taste and price.

Junmai daiginjo: Tatenokawa “18”

This set of three Dassai mini-bottles is a fantastic way to begin understanding the effects of rice polishing. It allows you to taste the same junmai daiginjo at three different RPR’s: 23%, 39% and 45%. It even comes with real rice grains to demonstrate the visual difference in polishing. Reference materials and Dassai glasses are also included to help you learn and sip.

At an almost unheard-of 18% rice polishing ratio, this is among the most heavily milled sake on the market — over 80% of each Yamadanishiki grain is polished away before brewing. That extreme reduction strips the rice down to its purest starchy heart, producing an intensely fragrant, delicate sake with juicy melon, pear and apple notes and a sweet finish. It’s a dramatic illustration of how far RPR can be pushed to achieve impressive aroma and elegance.

TATENOKAWA, Inc. built its reputation on pushing polishing to this kind of extreme, and “18” is an award-winning example of that. Because the rice polishing is so intense, more time and rice is required to make this luxurious bottle, raising the price to over $250.

Junmai Ginjo: Nito “Yamadanishiki 55”

Polished to 55%, this junmai ginjo sits comfortably within the classic ginjo-grade range, milled just enough to unlock aromatic complexity from its Yamadanishiki rice without erasing its earthier character entirely. The result is a fragrant, slightly savory profile. Floral and citrus sit up front, with an unexpected mushroom note giving it more depth than a typical fruit-forward ginjo. It’s a good example of ginjo-level polishing milled beyond the junmai baseline for lift and clarity, but not pushed to daiginjo extremes. Nito is known for showcasing single rice varieties this way, letting the RPR do the work of shaping the sake’s personality. While well-polished, it’s affordable at less than $45.

Tokubetsu Junmai: Hakkaisan “Tokubetsu Junmai” (RPR 60%)

“Tokubetsu” (special) here refers to polishing beyond the standard junmai baseline, and at 60% RPR, this Gohyakumangoku rice sake sits right at the edge of that special designation. The moderate polish preserves more of the rice’s amino acids and body than a ginjo-grade sake, translating into a fuller mouthfeel layered with floral, cream and vanilla notes. Despite that richness, the profile stays notably dry and clean rather than heavy. It’s a nice demonstration of how tokubetsu junmai occupies the middle ground; it’s more refined than an everyday junmai, but doesn’t chase the fragrance of ginjo sake. It’s very wallet-friendly at less than $30.

Junmai: Harada “Junmai 80”

At 80% RPR, most of the Yamadanishiki rice grain’s outer layers — containing fats, proteins and minerals — are left intact. That minimal polish shows up as a rich, dry sake with mango and rice notes, plus a savory anise edge. It’s an illustration of how junmai sake leans on rice character rather than aromatics. Compared with a ginjo or daiginjo from the same rice, this bottle is proof that RPR — not the rice variety alone — drives a lot of the flavor difference. Enjoy it for less than $40.

Tokubetsu Honjozo: Hakkaisan “Tokubetsu Honjozo” (RPR 55%)

This tokubetsu honjozo is polished to 55%, which surpasses the tokubetsu honjozo requirement of 60%. The added polish, combined with a touch of brewer’s alcohol, produces a clean, light and dry sake with watermelon and grain notes. That small addition of alcohol during brewing also lifts the aromatics and smooths the texture compared to a junmai at a similar polish level. It’s a good example of how honjozo-style sake uses both polishing and alcohol addition together to shape a crisp, refreshing profile that is satisfying at various serving temperatures. Hakkaisan “Tokubetsu Honjozo” is a reliable, food-friendly staple at less than $40.

Honjozo: Kikusui “Karakuchi” (RPR 70%)

Milled to 70%, this Niigata-born sake sits at the required honjozo polishing level. Its herbaceous, anise and mineral notes reflect that rustic, rice-driven character. The small addition of brewer’s alcohol — a defining trait of honjozo — keeps the palate light. This RPR illustrates honjozo’s core appeal: an everyday, food-friendly sake style where alcohol addition compensates for less intensive polishing, keeping both quality and cost accessible at less than $30.

Rice polishing is a major indicator for sake taste — but not the only one

If you’re not sure what a sake tastes like, looking at its rice polishing ratio can give you a major clue. While it’s not the end-all-be-all factor that determines taste and pricing, it is a significant one. If you enjoy delicate, refined brews that are fruity, floral and clean, a ginjo or daiginjo is your best bet. Want a bottle that’s versatile with a bit more character? Junmai, honjozo and futsushu fit the bill.

Still, it’s important not to get too caught up in analyzing digits. You might miss out on other good sake if you rely too heavily on it! Additional components that affect the final product include brewer’s alcohol, yeast, pasteurization, filtering and more. Trying sake from different categories is a great way to expand your sake knowledge and enhance your drinking experience.

Reference:

National Tax Bureau Sake Production 2017
https://www.ssnp.co.jp/news/liquor/2018/02/2018-0207-1109-14.html