Is Homemade Tempeh Actually Cheaper?
Tempeh has earned a permanent spot in plant-based kitchens — but at $4–$6 per pound at most grocery stores, the cost adds up fast. Making tempeh at home sounds frugal, but you need to account for every input: dry soybeans, the live-culture starter, and the electricity your incubator draws over a 28–30 hour fermentation window.
The math usually works out in your favor. A pound of dry soybeans expands during soaking and fermentation, yielding roughly 1.5 pounds of finished tempeh. Dry soybeans typically run $1.00–$2.00 per pound in bulk, and a single starter packet ($2.50–$4.00) stretches across four or more batches. Incubation at a gentle 85–90°F draws about 30 watts for 29 hours — roughly 0.84 kWh per batch, which costs less than $0.15 at most U.S. electricity rates.
Put together, a typical batch of homemade tempeh lands between $1.00 and $1.80 per pound, compared to $4.00–$6.00 at retail. That is a 60–75% saving on a protein source that rivals chicken in protein density and beats it on fiber.
Tips for keeping your cost low
- Buy soybeans in bulk. A 25 lb bag from an Asian grocery or co-op can cut your soybean cost by 40% versus packaged beans.
- Re-culture your starter. Some fermenters break off a small piece of each successful batch to inoculate the next one, driving starter cost toward zero after the first packet.
- Use passive incubation tricks. A styrofoam cooler with a low-wattage heat mat can incubate a batch on less electricity than a full-size setup.
- Batch in parallel. The marginal electricity cost of a second or third tray in the same incubator is nearly zero, slashing the per-pound cost further.
Frequently Asked Questions
How much tempeh does 1 pound of dry soybeans make?
One pound of dry soybeans typically yields about 1.5 pounds of finished tempeh after soaking, dehulling, cooking, and 28–30 hours of fermentation. The beans absorb water and bind into a firm cake, increasing in weight even as some moisture evaporates during the warm incubation phase.
How much electricity does incubating tempeh use?
A typical DIY tempeh incubator — a seedling heat mat or small lightbulb setup — draws roughly 25–35 watts. Over a 28–30 hour ferment that works out to about 0.84 kWh. At the U.S. average rate of $0.13/kWh, that is around $0.11 per batch, a negligible fraction of the total cost.
Can I reuse tempeh starter from a previous batch?
Yes. If your batch sporulates fully (turns uniformly grey-white with visible spores), you can dry and save a small portion as starter for the next batch. Many experienced fermenters do this for several cycles, which drives the starter cost toward zero. Commercial starters tend to be more reliable for beginners, but home-saved spores work well once you have a reliable process.
What soybeans are best for tempeh and where do I buy them cheaply?
Dry, non-GMO soybeans work best. Asian grocery stores, bulk-food co-ops, and online retailers often carry 10–25 lb bags at $1.00–$1.50 per pound — far cheaper than the $2.50–$4.00 you'll pay for small packaged bags.
Is homemade tempeh always cheaper than store-bought?
In most cases yes, but location matters. If you live somewhere with very high electricity rates or pay a premium for organic soybeans, your cost per pound can approach the low end of store pricing. The bigger the batch and the cheaper your bulk soybeans, the more you save.