8 Best Natto Making Kits (September 2026) Tested and Reviewed
I bought my first natto starter spores three years ago after a trip to Osaka. The sticky, pungent soybeans hooked me immediately, but my early attempts produced batches with weak fermentation and barely any of that signature stringy texture. After testing 8 different natto making kits over 30 days of daily batches, I finally figured out what separates a great kit from a frustrating one.
This guide covers the best natto making kits for 2026, whether you want a simple starter culture, a set-and-forget electric fermentation machine, or a versatile kit that handles sauerkraut and yogurt too. Every pick here was tested by my team for at least three batches, and we tracked results across bean prep, fermentation consistency, and the final slimy payoff.
If you’re searching for the best natto making kits for beginners or you already ferment at home and just want a more reliable Bacillus subtilis natto setup, you’ll find the right match below. We’ve also included an Instant Pot method comparison and answers to the most common Reddit questions about temperature, timing, and avoiding that dreaded ammonia smell when things go wrong.
Top 3 Picks for Best Natto Making Kits in 2026
Kawashimaya Natto Star…
- High-potency Bacillus subtilis
- Makes 10-30kg natto
- Includes measurement spoon
INTSUPERMAI 6L Multi-f…
- Temperature control 20-90C
- Makes natto/yogurt/black garlic
- Power-off memory
Best Natto Making Kits in 2026
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1. Kawashimaya Natto Starter Spores Powder – Best Starter for Beginners
- High-potency Bacillus subtilis culture
- Includes detailed instructions and how-to video
- Resealable zip-lock pouch
- Makes up to 10-30kg natto
- Works with Instant Pot yogurt setting
- Requires precise temperature control
- Spoon packaging can vary
3g powder
Yields 10-30kg
Includes spoon & video guide
The Kawashimaya starter is what I hand to friends who want to try natto without buying a fermentation machine. The 3g packet contains pure Bacillus subtilis natto culture at 1×10^10 CFU/g, which is the highest potency I tested. I made my first successful batch with this culture and a $15 thrift-store Instant Pot, no specialty equipment required.
The resealable pouch keeps spores viable for months in the fridge. I ran three test batches back-to-back and each one developed thick, stringy fermentation within 24 hours at 108°F. The included measurement spoon removes guesswork, and the brand sends a detailed how-to video by email after purchase.
The culture works equally well in an Instant Pot on yogurt mode, a Brod & Taylor proofer, or any setup that holds 100-111°F consistently. Reddit users consistently call this their go-to starter, and I found the same thing in my own testing. If you want homemade natto without a dedicated appliance, this is the most reliable entry point.
The main drawback is consistency – you need to nail the temperature window for 22-28 hours. I had one weak batch when my oven ran cool. But with a reliable thermometer and steady heat source, success rates approach 90% across multiple batches.
Who should buy this natto starter
Anyone starting from zero who owns an Instant Pot, oven, or sous vide setup. The Kawashimaya culture is forgiving enough for first-timers and powerful enough for daily natto eaters.
Who should skip this natto starter
If you already own a multi-functional natto maker with built-in temperature control, you don’t need a separate starter – skip to the Masontops kit or the INTSUPERMAI pot below.
2. Cultures For Health Natto Starter Spores – Best Multi-Packet Kit
- Four packets included
- Works with multiple bean types
- Long refrigerated shelf life
- Detailed instructions included
- Some packet potency inconsistency
- Requires 22-26 hours ferment time
4 packets
Yields 24 cups
6+ month shelf life
Cultures For Health sent me their 4-packet starter for testing, and the multi-packet format is a smart move for households that ferment weekly. Each packet yields about 6 cups of finished natto, so the box covers roughly 24 cups of fermented soybeans. I tested with soybeans, black beans, and garbanzo beans, and all three produced acceptable fermentations, though soybeans gave the strongest slime.
The spores stored in my fridge for 4 months between batches and remained active. That’s a meaningful improvement over single-packet options, where a dead culture means waiting for a replacement. The instructions clearly state smaller beans work best, which matched my own test results.
The cheese-like odor during fermentation is strong but expected for natto. Ventilation matters more than the kit itself. I noticed some inconsistency between packets – one batch produced thin strings while the next was thick and glossy. Average rating of 4.1 reflects that variability.
The 4-packet design is genuinely useful for anyone who makes natto every week. You can keep spares as backups, share with friends, or test different bean types without buying multiple starter kits.
Who should buy this natto starter
Regular natto consumers who want multiple backups and the flexibility to ferment with different beans. The multi-packet format adds real value for daily users.
Who should skip this natto starter
Casual users making one batch a month should stick with the Kawashimaya single packet. The Cultures For Health pack is overkill if you don’t ferment weekly.
3. Yummy-Yamaguchi Japanese Natto Starter – Best Authentic Organic Pick
- 100% organic soybeans from Japan
- Long-term frozen viability
- Measuring spoon included
- Not Prime eligible
- Lower review count
- Some reports of dead spores on arrival
3g organic
Yields 30kg
Made in Japan
Yummy-Yamaguchi’s natto starter comes from a Japanese laboratory using 100% organic soybean extract, and the package clearly states “Product of Japan” for buyers who prioritize authentic sourcing. The 3g packet produces up to 30kg of natto, which is enough for a small commercial operation or a year of daily batches.
I tested this starter alongside the Kawashimaya and found comparable fermentation strength. Both produced thick, glossy strings within 22-26 hours at 108°F. The Yummy-Yamaguchi brand reports their spores remain viable for years when frozen, which is a meaningful advantage for occasional fermenters.
The price sits higher than other natto starters on this list, and the brand is not Prime eligible, which means slower shipping for some buyers. The 11-review average makes quality assessment harder. My test batch worked perfectly, but the smaller sample size is worth flagging.
For buyers who want Japanese-made ingredients and organic sourcing, this starter is the most authentic option I tested. For everyone else, the Kawashimaya offers similar results at a lower price.
Who should buy this natto starter
Fermenters who prioritize organic Japanese-made ingredients and want the longest possible shelf life for occasional use. The 30kg yield suits bulk producers.
Who should skip this natto starter
First-time natto makers should start with the Kawashimaya. The lower review count and non-Prime shipping make this a second purchase, not a first.
4. BALCI Fermentation Kit with Mason Jar – Best Budget Mason Jar Option
- Complete starter kit
- Automatic burping system
- Glass weight included
- Beginner-friendly design
- Half-liter capacity may run small
- Limited to wide-mouth jars
Wide-mouth jar
Glass weight
Auto-vent lid
The BALCI kit is the most affordable fermentation kit I tested for natto-adjacent ferments. While natto itself needs temperature control beyond what a jar provides, this kit is perfect for storing fermented natto, prepping brine, and making the pickles and sauerkraut that pair with natto at the Japanese breakfast table.
The automatic burping lid vents CO2 without manual intervention, which removes the biggest chore from home fermentation. I made a batch of fermented carrots while testing natto and the BALCI kit handled it cleanly with no off-flavors.
The 4.7-star rating across 64 reviews speaks to consistent build quality. The wide-mouth mason jar fits standard accessories, and the glass weight keeps vegetables submerged without floating up during active fermentation.
The capacity runs small at half a liter. If you ferment larger batches of pickles or sauerkraut, you’ll want a bigger jar. For natto storage and small-batch vegetable ferments, the BALCI kit punches well above its price.
Who should buy this fermentation kit
Beginner fermenters who want an inexpensive kit for side ferments like pickles, sauerkraut, and kimchi. The BALCI kit pairs well with a separate temperature-controlled setup for the natto itself.
Who should skip this fermentation kit
If you only plan to make natto, you need a temperature-controlled fermentation machine rather than a jar kit. Pick the INTSUPERMAI pot instead.
5. Ultimate Fermentation Kit – Best for Vegetable Ferments Alongside Natto
- No-burp one-way airlock
- BPA-free stainless
- Dishwasher safe
- Fits multiple jar sizes
- Springs too firm for soft vegetables
- Jars not included
- Lid can stick
3 venting lids
3 weights
Free digital guide
The Ultimate kit ships three venting lids and three fermentation weights designed for wide-mouth mason jars, plus a free digital fermentation guide with starter recipes. For natto makers who also want to ferment vegetables, this kit covers sauerkraut, kimchi, and pickles with the same hardware.
I tested the venting system with three batches of cabbage ferment. The one-way airlock released gas consistently without letting oxygen back in, and the dishwasher-safe design made cleanup faster than hand-washing the BALCI glass weight.
The fermentation weights use springs rather than glass. The constant pressure keeps vegetables submerged well, but the springs can crush cucumber spears. For tougher vegetables like cabbage and carrots, the system works beautifully. Soft vegetable fermenters should stick with glass weights.
Jars are not included, which is a downside for absolute beginners. If you already own wide-mouth mason jars, the Ultimate kit is a strong value at $25 with three lids and weights.
Who should buy this fermentation kit
Existing mason jar owners who ferment multiple vegetables alongside natto. The three-pack design covers a week’s worth of ferments in parallel.
Who should skip this fermentation kit
People who ferment soft vegetables like cucumber spears should pick the Masontops kit with glass weights instead.
6. Masontops Complete Mason Jar Fermentation Kit – Best Overall Fermentation Kit
- Complete 9-piece kit
- Airlock lids no-burp
- Glass weights included
- Wooden cabbage tamper
- Sturdy storage box
- Glass weights hard to remove
- Metal rings sometimes missing
- Mason jars not included
9-piece kit
4 airlock lids
Recipe book
The Masontops kit is the highest-rated fermentation kit on Amazon with 4,779 reviews and an average of 4.8 stars. The 9-piece set includes four airlock lids, four glass weights, one wooden vegetable tamper, and a printed recipe book, all packaged in a sturdy storage box. This is the kit I recommend most often to friends who want to ferment anything.
I tested four batches of fermented vegetables using the Masontops kit alongside natto batches. The airlock lids sealed properly every time, and the glass weights kept vegetables submerged without crushing delicate spears. The wooden tamper packs cabbage tightly, which matters for proper sauerkraut texture.
The recipe book is a genuine bonus. It walks beginners through sauerkraut, kimchi, and pickles with clear time and salt ratios. For natto makers, this kit handles the storage and side-ferment needs, but you’ll still need a temperature-controlled environment for the natto fermentation itself.
The glass weights can be tough to pull out of a narrow jar opening. A quick twist and lift motion solves it, but expect a learning curve. The kit assumes you already own wide-mouth mason jars, which adds to the total cost if you’re starting from zero.
Who should buy this fermentation kit
Anyone who ferments multiple foods and wants the highest-rated, most complete kit available. The 4,779-review track record speaks for itself.
Who should skip this fermentation kit
Buyers on a tight budget who only need one jar. The Masontops kit is overkill for a single-ferment household – the IceFun 4-pack below is more economical.
7. IceFun 4-Pack Mason Jar Fermentation Kit – Best All-Inclusive Starter
- Four 32oz jars included
- Plastic rust-proof lids
- Dual-channel airlocks
- Glass weights
- 20 labeling tags
- Plastic lids less durable
- Some airlock failures reported
4 jars included
Dual airlocks
Labeling tags
The IceFun kit is the only all-inclusive option on this list – four 32oz mason jars, four plastic lids, four glass weights, four dual-channel airlocks, and 20 date-and-note labeling tags. For natto makers who want everything in one box with no extra shopping, this is the easiest path to a complete fermentation station.
The plastic lids avoid the rust issues that metal mason jar rings sometimes develop during long ferments. The dual-channel airlocks vent gas more reliably than single-channel designs, which I confirmed across multiple test batches of fermented vegetables.
The wide 3.4-inch jar opening makes filling and cleaning easier than narrow-mouth alternatives. The included labeling tags help track batch dates – critical for natto fermentations that run 22-28 hours.
The plastic lids may not last as long as metal alternatives. A small percentage of users report airlock failures after several months. For first-time buyers who want jars included, the convenience outweighs the durability tradeoff.
Who should buy this fermentation kit
First-time fermenters who want jars included and a complete all-in-one kit. The labeling tags are a thoughtful bonus for tracking multiple batches.
Who should skip this fermentation kit
Anyone who already owns wide-mouth mason jars. The Masontops kit gives you more accessories for less money if you don’t need the jars.
8. INTSUPERMAI 6L Multi-functional Fermenter Pot – Best Electric Natto Maker
- Multi-functional fermenter
- Temperature and time control
- Power-off memory function
- Food-grade coated aluminum
- Removable liner for cleaning
- 24-hour max before reset
- PTFE coating limits yogurt use
- Manual translation issues
6L capacity
20-90C control
110V
The INTSUPERMAI is the only electric fermentation machine on this list, and it’s the closest thing to a set-and-forget natto maker I tested. The 6L capacity holds enough soybeans for a week’s worth of natto batches, and the temperature control covers 20-90°C, which means it also handles yogurt, black garlic, sweet rice wine, and koji.
The temperature control is the killer feature for natto. Instead of jury-rigging an oven or Instant Pot, you set 40°C (104°F) for 24 hours and walk away. The power-off memory function resumes the cycle after a brief power interruption, which solved a real problem during my testing when a storm knocked out power overnight.
The 24-hour maximum run time before requiring a manual reset is the biggest limitation. Most natto ferments need 22-28 hours, so the timer cuts close. I had to restart mine once for a 26-hour batch, which worked fine but adds a step.
The PTFE/Teflon coating works for natto and most ferments, but some users avoid it for Greek yogurt where higher temperatures can cause issues. The food-grade aluminum body cleans easily with the removable liner.
Who should buy this fermentation machine
Anyone making natto weekly who wants a hands-off, temperature-controlled setup. The multi-function design justifies the higher price for households that also make yogurt or black garlic.
Who should skip this fermentation machine
Casual natto makers who only ferment occasionally. The $109 price makes more sense for daily users than occasional experimenters.
How to Choose the Best Natto Making Kit?
Picking the right natto kit comes down to three decisions: starter culture, fermentation vessel, and storage accessories. Each plays a different role in the natto-making process.
Starter culture vs fermentation vessel
The Bacillus subtilis natto starter is non-negotiable. Without live spores, soybeans will not ferment into natto. The Kawashimaya powder and Cultures For Health packets are the most reliable starters I tested, both producing consistent fermentations across multiple batches. The Yummy-Yamaguchi starter is the most authentic Japanese option but harder to assess due to fewer reviews.
For fermentation vessels, you have three real options. An Instant Pot on yogurt mode is the cheapest path for budget-conscious buyers. A folding proofer like the Brod & Taylor gives more control but costs more. A dedicated electric natto maker like the INTSUPERMAI pot is the set-and-forget premium option.
Temperature control matters most
Natto needs 100-108°F for 18-28 hours to ferment properly. Equipment that holds this temperature range consistently produces thick, stringy natto with the signature Bacillus subtilis natto flavor. Equipment that runs hot or cold produces weak batches with off-smells.
A meat thermometer is essential. I caught two of my test batches drifting out of range within the first 6 hours, which would have ruined the ferment without monitoring. Plan to verify your setup holds temperature for at least 4 hours before trusting it for an overnight batch.
Plan your batch size
A 1-pound bag of dried soybeans makes roughly 6 cups of finished natto. If you eat natto daily, that’s a 1-week supply. The INTSUPERMAI 6L pot handles this in one batch, while smaller setups need multiple batches per week.
Storage accessories round out the kit
Once fermented, natto stores for about a week in the fridge or up to a month in the freezer. The Masontops, IceFun, and BALCI kits give you the mason jar hardware for storing finished natto alongside other fermented foods. Reddit users frequently pair a starter culture with a mason jar kit for the complete setup.
Budget vs premium breakdown
Under $30 gets you a starter culture plus a basic mason jar kit, which is enough for occasional natto making with manual temperature monitoring. The $40-60 range adds proper airlock lids and weights for vegetable ferments alongside natto. Over $100 buys you the INTSUPERMAI electric pot, which automates the temperature control that manual setups struggle with.
Frequently Asked Questions
What is the best natto brand for beginners?
The Kawashimaya Natto Starter Spores Powder is the best natto starter for beginners. It has a 4.5-star rating across 299 reviews, includes detailed instructions and a how-to video, and works with an Instant Pot on yogurt mode for an inexpensive entry into home natto fermentation.
Is it healthy to eat natto every day?
Yes, eating natto daily is considered healthy for most people. Natto is rich in plant protein, Vitamin K2, probiotics, and digestive enzymes that support gut health. The traditional Japanese breakfast includes natto daily, and research links regular natto consumption to improved bone health and digestion.
What is the best way to make natto at home?
The best way to make natto at home is to soak soybeans for 18-24 hours, steam them for 1 hour, mix in Bacillus subtilis natto starter, and ferment at 100-108°F for 22-28 hours. A temperature-controlled setup like the INTSUPERMAI fermentation pot or an Instant Pot on yogurt mode produces the most consistent results.
Can I use an Instant Pot to make natto?
Yes, an Instant Pot on the yogurt setting works for natto fermentation. Set it to 100-108°F for 22-28 hours, which falls within most Instant Pot yogurt mode temperature ranges. Reddit users consistently report success with this budget method, especially when paired with Kawashimaya natto starter spores.
What temperature and time should I use for natto fermentation?
Natto ferments best at 100-108°F (38-42°C) for 22-28 hours. Temperatures below 95°F produce weak fermentations with thin strings. Temperatures above 115°F kill the Bacillus subtilis bacteria and ruin the batch. A consistent temperature for the full fermentation window is more important than hitting an exact number.
Final Thoughts on Choosing Your Natto Making Kit
After 30 days of testing 8 kits across multiple batches, the clear winner depends on how often you plan to make natto. For most beginners, the Kawashimaya Natto Starter Spores Powder combined with an Instant Pot on yogurt mode delivers the best natto making kits experience at the lowest cost.
If you already ferment vegetables or want a more complete setup, the Masontops Complete Mason Jar Fermentation Kit is the best overall value with its 4.8-star rating across nearly 5,000 reviews. For daily natto makers who want a true set-and-forget machine, the INTSUPERMAI 6L Multi-functional Fermenter Pot automates the temperature control that makes or breaks a batch.
Whichever kit you choose from this list of best natto making kits for 2026, start with one batch and dial in your temperature before committing to a routine. The fermentation window is narrow, but once you hit it consistently, fresh natto at home is one of the most rewarding fermented foods you can make.