Sizu Riatto
Flush Hour · Chapter 10

What It's Worth

Find out what your mushrooms cost a kilogram and how many tubs pay for the kit, before you buy it. Then dry the small flush and see what a stall would take to break even.

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Opens on the book's tub at illustrative US prices (pick UK above). Change any number to your own and press Calculate.

What one tub uses

Prices (put in your own)

The harvest and the kit

Drying (optional)

A market stall (optional)

Enter what a tub uses and the prices, then press Calculate.

The formula

  • Each line = amount × price per unit: straw = bale price × kg used ÷ bale kg; spawn = price a kg × kg used
  • Cost a tub = straw + spawn + electricity + gloves and mask; cost a kg = cost a tub ÷ kg harvested
  • Saving a tub = the harvest at the shop's price − the cost a tub; payback = the kit ÷ the saving a tub
  • Drying keeps the dry matter: dried = fresh × (1 − fresh water) ÷ (1 − dried water)
  • Stall break-even (kg) = the fee ÷ (your price a kg − your cost a kg)
The book's worked example, Chapter 10. The book's tub: straw 0.83, spawn 7.94, electricity 0.54, four gloves and a mask 4.08: 13.38 a tub. 1,455 g makes that 9.20 a kg, against 22 in the shop and 26.46 for a grow kit's best case. At the shop's price the harvest is worth 32.01, a saving of 18.63, so the 120.50 kit pays back in 6.47 tubs. Dried, the 148 g third flush weighs 17.66 g (8.38 : 1). UK: 14.06 a tub, 9.66 a kg against 15.70.
Check it. Before the drying, call the dried weight of 100 g of your mushrooms; then weigh it once it snaps.

Honest limits. Prices change and vary by shop and region: the stall fee is one market's published day rate, and the selling price is yours to set. A cost per kg leaves out your time, the water and a failed tub; a payback is a worked example, not a promise. The book's tub, its straw and its harvests were worked out on paper from published figures, not grown by us: weigh your own. Prices are illustrative, as seen in November 2026 (US mid prices, with UK beside where they differ), shown without a currency sign; put in your own. No yield or profit is promised. Everything stays in your browser: no sign-up, nothing stored.