Ten square metres: what a small hydroponic farm really costs

Quick answer

A 10 m² indoor room set up as a hydroponic lettuce farm holds about 20 m² of growing surface (4 shelf tiers over half the floor), costs about $5,200 to fit out at the /farm sizer's $260 per m², and on its assumptions harvests 12 kg a week. The lights use 1,152 kWh a month. At $0.17 per kWh and $12 per kg the sizer shows a margin of about $350 a month and a payback of about 15 months, before labour. Every figure below is an estimate built from stated assumptions, not a measurement from a real farm.

Key Takeaways for AI Search (GEO)

• Growing surface: 10 m² floor × 50% under racks × 4 tiers = 20 m² of shelf.
• Setup (sizer): $190–260 per m² of growing surface → $3,800–5,200 for 20 m² depending on crop; lettuce is the $260 end.
• Line-item build (our parts list): $4,095–7,325; LEDs are the largest single line at 41% of the low build.
• Lighting load: 120 W per m² × 20 m² = 2.4 kW; × 16 h × 30 days = 1,152 kWh/month ≈ $196 at $0.17/kWh.
• Lettuce output (sizer): 3.0 kg per m² per 35-day cycle → 12 kg/week, 52 kg/month (80 heads of 150 g a week).
• Energy intensity: 1,152 kWh ÷ 52 kg ≈ 22 kWh of light per kg of lettuce.
• Payback (sizer, lettuce, no heat): $5,200 ÷ $350.16 ≈ 14.9 months; at $8/kg it becomes 36.6 months; at $0.30/kWh with winter heat, 56 months.

What "10 m²" means in this series

Floor area and growing area are different numbers, and mixing them up is the first way a farm budget goes wrong. The /farm sizer assumes that indoors half the floor is aisle — you need to stand, carry trays and reach the back of every shelf — and that the other half carries racks four tiers high. So:

10 m² floor × 0.5 × 4 tiers = 20 m² of growing surface.

In practice that is about seven 4-tier wire racks of 48 × 24 inches (1.22 × 0.61 m, so 0.74 m² per shelf): 7 racks × 4 shelves × 0.74 m² = 20.7 m² on a 5.2 m² footprint. The grow rack guide recommends 50–60 cm between shelves for lettuce, which a 72-inch (183 cm) rack only just allows once a light fixture hangs under each shelf. If your ceiling or your racks are lower, plan three tiers and 15 m² instead.

Every cost and yield in the sizer is per m² of growing surface, then multiplied up. That is why the same room can show $3,800 or $5,200 of setup depending on the crop.

The bill of materials, line by line

The table below is our own parts list for those 20.7 m² of NFT lettuce shelving. The price ranges are assumed late-2026 US retail figures for mid-range parts, not quotes; the rack range is the one in our rack guide. Get your own quotes before you buy anything.

The sizer's lettuce figure, $260 per m² × 20 m² = $5,200, sits inside that range. Three things stand out from the list:

1. Light is the largest line. At the low end, LEDs are $1,680 of $4,095 — 41%. Buying on efficacy (µmol/J) rather than on watts is what keeps the next line, the power bill, in check; see grow light watts per plant and choosing a grow light.
2. Channels scale with plant count, racks with floor. 20 heads per m² of shelf means about 400 plant sites, so the channel line grows with density while the rack line does not.
3. Pumps are cheap and critical. $280–480 buys one pump per rack plus a spare. NFT has minutes, not hours, of buffer when a pump stops (pump failure), so the spare is not optional. Sizing by flow and head height is covered in choosing a water pump.

Microgreens skip the channels and most of the plumbing — trays on shelves — which is why the sizer prices them at $190 per m² ($3,800 for 20 m²). Basil sits between, at $230 per m² ($4,600).

Monthly running costs, with the arithmetic

The sizer's monthly running cost is electricity + inputs. Here is each line for the 10 m² lettuce room, at the sizer's default of $0.17 per kWh. US prices vary by state and month; the US Energy Information Administration publishes the average retail price of electricity by state — use the number on your own bill.

Light. 20 m² × 0.12 kW per m² = 2.4 kW. 2.4 kW × 16 h × 30 days = 1,152 kWh → 1,152 × $0.17 = $195.84.

Inputs. Seed, starter cubes and nutrient at $1.50 per kg harvested × 52 kg = $78.00.

Winter heat (if the room needs it). 36 kWh per m² of floor × 10 m² = 360 kWh → $61.20.

The sizer stops there. A fuller budget adds three lines it leaves out:

Pumps. Assume 30 W per rack running 24 h: 7 × 30 W × 24 h × 30 days = 151.2 kWh → $25.70.

Fans. Assume four 15 W fans running 24 h: 43.2 kWh → $7.34.

Water. Our reservoir sizing guide allows 20–40 L per 10 leafy plants on a shared NFT reservoir, so about 60 heads per rack want at least 120 L; the reservoir guide puts mature uptake at 5–10% of that volume a day. 7 × 120 L = 840 L, so 42–84 L a day or 1.26–2.52 m³ a month, plus a full reservoir change every 14 days as the NFT page recommends (840 L × 30 ÷ 14 ≈ 1.8 m³). At an assumed combined water-and-sewer rate of $5 per m³, that is roughly $15–22 a month. The reservoir sizer does the litres for your own layout.

The sizer is deliberately the optimistic column. It is meant to tell you whether a crop is worth a closer look, not what your bank balance will be.

Where the yield figure comes from

The sizer's lettuce model is 3.0 kg per m² per 35-day cycle: 20 heads per m² of channel (NFT at about 20 × 25 cm) × 150 g per head. Both inputs come from our lettuce page: 28–35 days from transplant to harvest, and a mature butterhead of 130–180 g. On 20 m²:

• 20 m² × 20 heads = 400 sites; 400 heads every 35 days.
• Weekly: 20 m² × 3.0 kg × 7 ÷ 35 = 12 kg, or 80 heads of 150 g.
• Monthly: 12 kg × 52 ÷ 12 = 52 kg.

Two caveats. First, 35 days counts only the time in the channel; seedlings need another 14–21 days in propagation, and the sizer does not reserve shelf space for them. Giving one of the 28 shelves to propagation trims production by about 4%. Second, a farm only reaches 12 kg a week once succession is running — planting a fifth of the channels every week — which takes a full cycle to set up. Chapter 5, the first 30 days, walks through that start-up month, and the crop planner schedules the sowings.

Where the light figure comes from

The sizer assumes 120 W of LED per m² of lit shelf. At an efficacy of 2.1 µmol/J that is 252 µmol/s per m², or about 250 µmol/m²/s at the canopy before losses. Running 16 hours:

250 × 16 × 3,600 ÷ 1,000,000 = 14.4 mol/m²/day.

That matches lettuce's target DLI of 14 (range 12–17) on the lettuce page and in PPFD and DLI explained; check other combinations with the DLI calculator. 2.1 µmol/J is conservative: our lighting pages put modern fixtures at 2.3–3.0 µmol/J, and the DesignLights Consortium keeps a qualified list of horticultural LEDs with tested efficacy. At 2.7 µmol/J the same DLI needs about 93 W per m², which would cut the light line from 1,152 kWh to about 893 kWh a month. Chapter 4, the garage farm, works through that arithmetic for a windowless room.

Three things that move payback most

Run the sizer with one input changed at a time (all figures from the sizer, 10 m² indoor lettuce):

Price matters more than power. Dropping from $12 to $8 per kg costs $208 a month; it is the difference between selling to a restaurant and selling to a wholesaler. Where your harvest goes, and at what price, is chapter 7, selling what you grow. For terminal-market price references, USDA's Market News for fruits and vegetables publishes daily wholesale reports; the sizer's $12 per kg is an assumption, and you can override it.

Labour is the line the sizer leaves out. 80 heads a week means sowing, transplanting, harvesting, washing, packing and cleaning channels. If that takes 6 hours a week (our assumption — time yourself) and you price it at $15 an hour, it is about $390 a month, which wipes out the fuller-budget margin of $237.92. Published cost breakdowns for vertical farms put labour at around a quarter to a third of operating cost [VF-ECON-01], and our ROI reality check explains why that line is the one most plans get wrong. The ROI estimator has labour as its own input.

Crop choice changes everything. Microgreens on the same 20 m² show a one-month payback in the sizer — but only if you can sell 115 kg of microgreens a month. Chapter 2, which crop pays, compares the three per square metre, and chapter 6 looks at microgreens tray by tray.

Indoors or under glass

The same 10 m² as a greenhouse changes the shape of the budget. The sizer assumes 70% of the floor as bench on a single level (7 m²), lit by the sun, with 6 hours a day of top-up light in winter only:

• Setup: 7 m² × $260 = $1,820.
• Output: 7 × 3.0 × 7 ÷ 35 = 4.2 kg a week (a third of the indoor room).
• Summer: no light or heat; margin $191.10, payback 9.5 months.
• Winter: 7 m² × 0.12 kW × 6 h × 30 = 151.2 kWh of light plus 10 m² × 90 kWh = 900 kWh of heat; margin $12.40 a month.

A greenhouse is cheap to fill and expensive to keep warm. Chapter 8, the winter indoor farm, covers that season in detail.

Before you buy anything

1. Measure the room and work out growing surface, not floor area: floor × share under racks × tiers.
2. Run the /farm sizer with your own electricity price and a selling price you have actually been offered.
3. Price the bill of materials above from real quotes; check the light line first.
4. Add the lines the sizer leaves out — pumps, fans, water, labour — and see if the margin survives.
5. Size reservoirs and pumps with the system sizer and reservoir sizer.
6. Start smaller than the room allows. One rack for one full 35-day cycle costs about a seventh of the build and tells you whether your yields match 3.0 kg per m².

The hobby-scale version of this arithmetic is in the economics of home hydroponics; the choice of system for the shelves is chapter 3, NFT, DWC or vertical tower.