Grow-your-own vs store cost calculator for mushroom kits
Enter what the mushroom grow kit cost and what you harvested, and see your cost per pound next to the store price.
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Enter your numbers and press Calculate.
How the math works
It is plain arithmetic, and every number comes from you.
- Total cost is the kit price plus shipping and tax.
- Cost per pound is total cost divided by the weight you picked.
- The store cost of the same weight is the store price times your harvest weight.
- The break-even harvest is total cost divided by the store price per pound.
A worked example
These numbers are made up to show the steps, not a typical result. Say a kit costs $34.99 and shipping and tax add $8, so the total is $42.99. You pick 1.25 lb across the flushes, and the store sells the same mushroom at $12 a pound.
- Cost per pound is $42.99 divided by 1.25 lb, which is $34.39.
- The same 1.25 lb at the store would cost $15.00.
- Break-even is $42.99 divided by $12, which is 3.58 lb.
North Spore says a first flush from its Spray & Grow kits typically weighs between half a pound and 2 lb. On these made-up numbers, one flush would not pay the kit back on price alone. Your store price and your harvest will differ, so run your own.
What weight should I enter?
Enter what you actually weighed, across every flush so far. North Spore says the first flush from its Spray & Grow kits typically weighs between half a pound and 2 lb, and that later flushes are usually smaller. It guarantees the first flush only, so a second flush is a bonus, not something to count on. These are the seller's figures, not our results.
What this does not count
The calculator leaves out your time, a spray bottle if the kit does not include one, and any electricity. Store prices also vary by mushroom and shop, so use the price of the kind you would really buy. To compare kits before you buy, see the best mushroom grow kits. For how to get a good harvest, see how to grow mushrooms at home.
Related pages
Common questions
Is growing mushrooms cheaper than buying them?
It depends on the kit price, how much you harvest and what the mushroom costs at your store. This calculator shows your own numbers side by side. We do not claim that growing is always cheaper.
What yield should I enter?
Enter what you actually weighed. North Spore says the first flush from its Spray & Grow kits typically weighs between half a pound and 2 lb, with later flushes usually smaller.
What does break-even mean here?
It is the harvest weight at which the store price of that weight equals what you spent on the kit and shipping. Below it, buying would have cost less.
Sources
- Spray & Grow Kit FAQ, North Spore. Checked November 11, 2026.
How this page is checked
Cedrick Reese built this calculator and checked it by hand. It only does arithmetic on the numbers you type, so there is no hidden assumption about price or yield. The one outside figure on the page, a typical first flush, comes from North Spore's FAQ and is labeled as the seller's. If the seller changes its figures, the page is updated, and the math itself does not change.