Seed Germination Calculator
Test germination rates and plan how many seeds to sow.
Use ToolFree calculator
Microgreen Tray Calculator
Seed per tray, expected yield and cost per pound for a microgreen grow.
Microgreen Tray Calculator
Chlorova · updated for 2026
Calculator
Quick samples
Click “Calculate” to see your results.
Seed loads are for a standard 1020 shallow flat, and the ~2.75× yield ratio is a healthy fresh-weight average — a dense sunflower tray converts lower by weight than an airy pea mat. Cost per pound reflects only seed you entered; add your own media, water and power to know a real margin.
The microgreen tray calculator sizes a flat of shoots from the seed up: pick a crop and it loads the ounces that fill one standard 1020 tray, multiply by how many trays you are running, and estimate the fresh-weight harvest at a typical conversion ratio. It then turns your seed cost into dollars per tray and — the number growers actually track — cost per pound of greens, which tells you whether a shelf of broccoli microgreens is a hobby or a market booth. Everything keys to the 1020 flat that every rack, dome and scale is built around.
How to Use the Microgreen Tray Calculator
- Pick the crop — the label shows the seed load for one 1020 shallow tray.
- Enter how many trays the grow will run, so totals scale across the whole batch.
- Type the seed cost per tray: divide a bag price by the trays it fills to get this figure.
- Read total seed needed so you buy enough up front rather than running short mid-sow.
- Check expected harvest in ounces and pounds to plan the yield you are actually chasing.
- Compare cost per pound against what greens sell for to judge whether the batch earns its keep.
The Seed, Yield and Cost Formulas, Explained
Three linked steps run off the tray. Seed: total ounces = the crop's per-tray load × tray count. Yield: microgreens convert seed to fresh weight at roughly 2.5–3×, so expected harvest = seed × 2.75, and ÷ 16 turns ounces into pounds. Cost: seed dollars = trays × cost-per-tray, and cost per pound is that total divided by the harvested pounds — the ratio that tells a grower where the break-even sits.
Why the seed loads differ so much: they are not weights of finished greens but of viable seed needed to carpet a tray evenly, and that depends entirely on seed size. A broccoli tray wants about 2.5 oz of tiny brassica seed, while sunflower needs 14 oz of big hulled kernels to hit the same density, and pea sits mid-range at five. The yield ratio folds that difference back in — heavy sunflower converts to a dense mat but a lower multiple of its seed weight, whereas light broccoli gives a delicate, airy crop — so cost per pound, not seed ounces, is the honest cross-crop comparison.
Worked Example: Four Trays of Pea Shoots
- You are running four 1020 trays of pea, seeding at about 5 oz per tray.
- Seed needed: 5 × 4 = 20 oz, so a 1 lb bag plus change covers the sow exactly.
- Expected yield at the 2.75× ratio: 20 × 2.75 = 55 oz, about 3.4 lb of fresh shoots.
- At $2 of seed per tray, the whole grow costs 4 × 2 = $8 of seed.
- Cost per pound: $8 ÷ 3.4 lb ≈ $2.35/lb of seed alone — before media, water and power.
- Compare that to market: pea shoots often sell for $15–$25 a pound, so the seed margin is enormous and the real costs live in the tray, not the bag.
- Run the same four trays in broccoli at 2.5 oz and the seed is cheaper and lighter, but the yield is a fraction of the pea mat — cost per pound, not cost per tray, is what reveals the difference.
Seed Load and Yield by Crop
Typical seed per standard 1020 shallow tray and a rough fresh-weight harvest, before the ordinary variability of a real rack. Hull sizes and germination rates shift these figures.
| Crop | Seed/tray | Yield/tray (oz) | Days to harvest |
|---|---|---|---|
| Pea / shoots | 4–6 oz | 12–16 | 10–14 |
| Sunflower | 12–16 oz | 14–18 | 8–12 |
| Radish (daikon) | 3–4 oz | 9–12 | 8–11 |
| Broccoli | 2–3 oz | 5–7 | 8–12 |
| Wheatgrass | 8–12 oz | 18–24 | 7–10 |
Key Terms
- 1020 tray
- The industry-standard flat (about 10 × 20 in) that every microgreen rack, dome and scale is built around — the calculator's unit tray.
- Seed load
- The ounces of seed that carpet one tray evenly; set by seed size, not by how much green you want.
- Yield ratio
- Fresh greens weighed against dry seed sown — roughly 2.5–3× for a healthy crop, the multiplier behind the harvest estimate.
- Cost per pound
- Seed cost divided by harvested weight — the figure that ranks crops by real efficiency and market margin.
- Hulling
- Removing sunflower seed shells before sowing; unhulled trays drop shells everywhere and complicate the harvest.
What This Means on a Growing Rack
- Buy seed by the tray, not the packet: convert a bulk bag into cost-per-tray (bag price ÷ trays it fills) and feed that number here — it is what makes cost-per-pound meaningful.
- The seed is the cheapest input in microgreens; media, your time and the killed trays that mold quietly dominate real cost, so treat cost-per-pound as a floor, not a bottom line.
- Over-seeding a dense crop like sunflower past its load trades a bigger seed bill for poorer airflow and more rot — more per tray is not more per pound.
- Track your own yield ratio after a few harvests: the 2.75× default is healthy-average, and your rack, water and temperature will move it either way.
- Stack crops by turnover: fast, high-ratio peas and sunflowers pay the rack's rent while the slow, low-yield broccoli fills an order — the cost-per-pound output makes that ranking instantly.
Common Mistakes & Fixes
- Buying a hobby packet and dividing its price by a couple of trays, when bulk seed quoted per tray is what makes cost-per-pound honest.
- Sowing every crop at the same seed weight, so tiny broccoli seeds a bare thin mat and big sunflower seed banks up, molds and wastes product.
- Judging a grow on cost per tray instead of cost per pound, which hides that a light, slow brassica can be pricier per harvested ounce than a heavy pea mat.
- Assuming the yield ratio is guaranteed — a cold rack, old seed or heavy hand on the misting drops the multiple and inflates your real cost.
- Forgetting the killed trays: a batch that went to mold still spent its seed, so count losses when you work out a true per-pound figure.
When to Use This (and When Not To)
Use it to plan any microgreen sow on standard flats — sizing the seed order, projecting the harvest and pricing the crop per pound for a market or a subscription box. It assumes soil-or-mat growing in shallow 1020 trays, so whole-bale wheatgrass, living-mat sales and hydroponic tower greens want their own math. For a single windowsill tray it is more precision than a hobby needs, and to build a full margin add media, water, power and labor on top of the seed cost the calculator reports.
Microgreen Tray Calculator: Frequently Asked Questions
How much seed goes in a microgreen tray?
It depends entirely on seed size: roughly 2–3 oz for tiny broccoli, about 5 oz for pea, and 12–16 oz for sunflower in a standard 1020 shallow flat. The goal is an even single layer of seed covering the medium — dense enough to knit into a mat, open enough to breathe.
How much do microgreens yield per tray?
A healthy 1020 tray typically harvests 8–16 oz of fresh greens, converting seed at roughly 2.5–3× its dry weight. Big sunflower and wheatgrass trays run heavy, delicate brassicas light — and germination rate, temperature and watering all move the number tray to tray.
What is cost per pound and why does it matter?
It is your seed cost divided by the weight you actually harvest — the metric that lets you compare a cheap, light broccoli tray against a pricier, heavy pea tray on equal footing. To price greens for sale or judge whether a crop earns rack space, cost per pound is far more honest than cost per tray.
Are microgreens profitable to grow?
Seed is rarely the problem: even at a couple of dollars a tray, cost per pound from seed alone is a small fraction of what microgreens sell for, often $15–$25 a pound or more. The real costs are media, power, labor and the trays you lose to mold — the calculator shows the seed floor so you can price the rest honestly.
Do I need a special 1020 tray?
Not strictly, but the whole trade is sized around it: a standard 1020 flat is about 10 × 20 inches, and seed loads, yields, domes, racks and scales are all quoted to fit it. Grow in another size and you simply scale the seed and harvest per square foot instead of per tray.
Which microgreen crop is easiest for a first grow?
Pea and sunflower are the classic beginner crops — both germinate fast, forgive a heavy hand, and yield a satisfying heavy tray. Radish is quick and nearly bulletproof too. Broccoli and finer brassicas are slower, need steadier moisture and show their age sooner, which is why they are worth the calculator's cost-per-pound check before you commit a whole rack.
Sources & Further Reading
- Microgreens: Production and Postharvest — University of California Agriculture & Natural Resources
- Growing Microgreens in 1020 Trays — Penn State Extension
- Microgreen Yield and Seeding Rates by Species — Cornell University Small Farms Program
Chlorova Gardening Team
Builds, checks and documents every tool we publish
Chlorova editorial review
Checked against extension-service publications
Formula verified against published references · Updated