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Miso Calculator — Koji, Soybean & Salt Ratios for Homemade Miso

Get precise soybean, koji, and salt ratios for any miso style, from sweet white shiro to aged red aka

Yield

2 lbs

Fermentation

6–12 months

Total Cost

$14.23

Add Seed Miso
Speeds fermentation, adds complexity

Ingredient Summary

2 lbs
Shinshu (Yellow) (907g)
Dry Soybeans
0.45 lbs
Rice Koji
0.99 lbs
Salt
0.22 lbs

Detailed Weights

IngredientPoundsGrams
Dry Soybeans0.45204
Rice Koji0.99449
Salt0.22100 (5.5 tbsp)
Seed Miso0.1464

Soybean Weight by Stage

Dry204g (0.45 lbs)
After Soaking (18–24 hr)367g (0.81 lbs)
After Cooking449g (0.99 lbs)

Fermentation

Fermentation Time6–12 months
Vessel Size Needed0.2 gallon
Final ColorGolden amber
Temperature60–75°F (room temp)

Cost Comparison

Homemade (per lb)$7.12
Store-Bought (per lb)$8.00
Artisan/Aged (per lb)$20.00

Total batch cost: $14.23 for 2 lbs of shinshu (yellow)

Pro Tips

Mashing: Soybeans should be soft enough to crush between your thumb and pinky. Mash thoroughly—smooth paste ferments more evenly than chunky.
Air Pockets: Pack miso tightly into the vessel and throw balls of paste to eliminate air pockets. Air causes mold and off-flavors.
Tamari Bonus: Dark liquid collecting on top is tamari—real soy sauce. Collect it separately or stir it back in for deeper flavor.

What You'll Need

Shiragiku Koji [Aspergillus oryzae] Spores Gluten-Free Vegan - 10g/0.35oz

Shiragiku Koji [Aspergillus oryzae] Spores Gluten-Free Vegan - 10g/0.35oz

$14.994.6
View on Amazon

TOMO Fermentation Crock with Weights - Ceramic Sauerkraut Pickling Crock - Stoneware Kombucha Brewing (7L)

4.7
View on Amazon
Koji Kin Starter Spore Sake Miso Dry Aged Steak Amazake

Koji Kin Starter Spore Sake Miso Dry Aged Steak Amazake

$19.504.6
View on Amazon
Shiragiku Koji [Aspergillus oryzae] Spores Gluten-Free Vegan - 10g/0.35oz

Shiragiku Koji [Aspergillus oryzae] Spores Gluten-Free Vegan - 10g/0.35oz

$14.994.6
View on Amazon

TOMO Fermentation Crock with Weights - Ceramic Sauerkraut Pickling Crock - Stoneware Kombucha Brewing (7L)

4.7
View on Amazon
Koji Kin Starter Spore Sake Miso Dry Aged Steak Amazake

Koji Kin Starter Spore Sake Miso Dry Aged Steak Amazake

$19.504.6
View on Amazon

As an Amazon Associate, we earn from qualifying purchases.

Price as of Jun 27, 2026. Product prices and availability are accurate as of the date indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.

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Example Calculations

12 lbs Shinshu (Yellow) Miso with Rice Koji

Inputs

Miso TypeShinshu (Yellow)
Batch Size2 lbs
Koji TypeRice Koji
Seed MisoYes

Result

Yield2 lbs (907g)
Dry Soybeans0.45 lbs (204g)
Rice Koji0.99 lbs (449g)
Salt0.12 lbs (54g, 3 tbsp)
Seed Miso0.14 lbs (64g)
Fermentation6–12 months
Total Cost~$7.69

Two pounds of shinshu miso uses a 1:1 koji-to-soy ratio with 10% salt. You need 0.45 lbs of dry soybeans (which become ~1 lb cooked), 0.99 lbs of rice koji, and 3 tablespoons of salt. Adding seed miso is recommended for consistent results. Total cost about $7.69 vs $12–$20 for store-bought.

25 lbs Aka (Red) Miso with Rice Koji

Inputs

Miso TypeAka (Red)
Batch Size5 lbs
Koji TypeRice Koji
Seed MisoYes

Result

Yield5 lbs (2,268g)
Dry Soybeans1.27 lbs (576g)
Rice Koji2.23 lbs (1,012g)
Salt0.53 lbs (240g, 13.3 tbsp)
Seed Miso0.35 lbs (159g)
Fermentation12–24 months
Total Cost~$16.80

Five pounds of aka miso uses an 0.8:1 koji-to-soy ratio with 13% salt for its bold, aged flavor. The higher salt content preserves the miso during the 1–2 year fermentation. At ~$3.36/lb homemade vs $8–$12/lb store-bought, you save significantly on a larger batch.

Frequently Asked Questions

Q

What is the koji-to-soybean ratio for different miso types?

The ratio varies by miso style: shiro (white) uses 2:1 koji to cooked soybeans for a sweet, mild flavor. Shinshu (yellow) and mugi (barley) use 1:1 for balanced flavor. Aka (red) uses 0.8:1 for a soy-forward, intensely savory paste. Hatcho uses 0.5:1 soy koji for the most concentrated umami.

  • Shiro (white): 2:1 koji to cooked soy — sweet, mild, 1–3 months
  • Shinshu (yellow): 1:1 koji to cooked soy — versatile, 6–12 months
  • Mugi (barley): 1:1 barley koji to cooked soy — earthy, 8–18 months
  • Aka (red): 0.8:1 koji to cooked soy — bold umami, 12–24 months
  • Hatcho: 0.5:1 soy koji to cooked soy — intense, 18–36 months
Miso TypeKoji:Soy RatioSalt %Ferment Time
Shiro (White)2:15%1–3 months
Shinshu (Yellow)1:110%6–12 months
Aka (Red)0.8:113%12–24 months
Hatcho0.5:112%18–36 months
Q

How much salt goes into miso?

Salt content ranges from 5% for sweet shiro miso to 13% for aged aka. The formula is: salt = (cooked soy weight + koji weight) × salt percentage ÷ (1 − salt percentage). For a 2-pound batch of shinshu miso (10% salt), that’s roughly 3–4 ounces of salt. Use non-iodized sea salt or kosher salt—iodine can inhibit fermentation.

  • Shiro: 5% salt — very low, ferments quickly but spoils faster
  • Shinshu: 10% salt — balanced preservation and flavor
  • Mugi: 11% salt — slightly higher for the longer ferment
  • Aka: 13% salt — high salt preserves during 1–2 year fermentation
  • Use sea salt or kosher salt only — iodized salt inhibits koji enzymes
Miso TypeSalt %Salt per 2 lbs MisoFlavor Impact
Shiro5%~1.5 ozSweet, delicate
Shinshu10%~3.2 ozBalanced, savory
Aka13%~4.7 ozBold, salty-umami
Hatcho12%~4.3 ozIntense, bitter-sweet
Q

How long does miso need to ferment?

Fermentation time depends on the miso type and ambient temperature. Shiro (white) miso is ready in 1–3 months. Shinshu (yellow) takes 6–12 months. Aka (red) needs 12–24 months, and hatcho can take up to 36 months. Warmer temperatures (70–75°F) speed fermentation; cooler rooms slow it. The miso develops deeper flavor the longer it ages.

  • Shiro: 1–3 months at room temperature (fastest)
  • Shinshu: 6–12 months, most versatile and popular
  • Mugi: 8–18 months, earthy barley flavor develops slowly
  • Aka: 12–24 months for deep red-brown color and intense umami
  • Hatcho: 18–36 months, the most aged traditional miso
Miso TypeFerment TimeFlavor ProfileBest Uses
Shiro1–3 monthsSweet, mildDressings, marinades
Shinshu6–12 monthsBalanced, savorySoup, all-purpose
Aka12–24 monthsBold umamiHearty soups, glazes
Hatcho18–36 monthsIntense, complexRich stews, sauces
Q

What is seed miso and do I need it?

Seed miso (tane miso) is a small amount of finished miso (5–10% of batch weight) mixed into the new batch. It inoculates the fresh miso with beneficial bacteria and enzymes, speeding up fermentation and adding complexity. It’s not strictly required—miso ferments fine without it—but it’s especially helpful for beginners.

  • Use 5–10% of target batch weight as seed miso
  • Any unpasteurized miso from the store works as seed
  • Provides beneficial Bacillus subtilis bacteria to jumpstart fermentation
  • Especially recommended for first-time miso makers
  • For 2 lbs of miso, add 1.5–3 oz of finished miso as seed
FactorWith Seed MisoWithout Seed Miso
Ferment Speed10–15% fasterStandard pace
Flavor ComplexityMore complexSimpler
Beginner SuccessHigherModerate
Amount Needed5–10% of batchNone
Q

How much does homemade miso cost vs store-bought?

Homemade miso costs $3–$6 per pound depending on koji prices, while store-bought ranges from $6–$12 per pound for commercial brands and $15–25 per pound for artisan aged miso. The biggest cost is koji at ~$12/lb. Making larger batches (5–10 lbs) brings the per-pound cost down significantly since koji can be bought in bulk.

  • Homemade shiro miso: ~$4–$5/lb (lots of koji)
  • Homemade shinshu: ~$3–$4/lb (balanced ratio)
  • Homemade aka: ~$3/lb (less koji, more soy)
  • Store-bought commercial: $6–$12/lb
  • Artisan/aged miso: $15–$25/lb or more
SourceShiro/lbShinshu/lbAka/lb
Homemade$4–$5$3–$4$3–$4
Store-Bought$6–$8$6–$10$8–$12
Artisan$12–$18$15–$20$18–$25

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Last Updated: Jul 13, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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