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Potato Seed Calculator
Pounds of seed potatoes, cut pieces and estimated harvest for your row feet.
Potato Seed Calculator
Chlorova · updated for 2026
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Click “Calculate” to see your results.
Pieces-per-pound and yield-per-piece are averages for certified seed in decent ground; a wet spring, poor hilling or a variety prone to scab will pull both down. Buy certified disease-free seed from a seed supplier — grocery potatoes are often sprout-suppressed and can carry viruses no rotation fixes, and the harvest you planned on this calculator does not happen if the seed itself is the problem.
The potato seed calculator turns a length of row into the order weight and the harvest you can expect from it. Seed potatoes are sold by the pound and cut into chunks with one or two eyes each, so the real question is not 'how many plants' but 'how many pounds and how many chunks to cut'. Enter your row length, spacing and preferred seed size, and it returns the piece count, order weight, cost and a realistic season yield. That is the arithmetic that keeps a first-year gardener from ordering fifty pounds for fifteen feet of bed.
How to Use the Potato Seed Calculator
- Choose seed size — small whole, medium cut or large cut.
- Enter the row feet you can actually plant in the garden.
- Set the in-row spacing; twelve inches is the conventional default for most varieties.
- Type your supplier's per-pound price to get a real cost.
- Read the pieces, pounds and cost so the seed order actually matches the row you have.
- Order early — the best varieties sell out by late February in most regions.
- Chit (sprout) the seed two to three weeks before your planting window to speed emergence.
The Seed-Potato Order Math, Explained
Pieces to plant = row feet × 12 ÷ in-row spacing, rounded up so the last foot of row still gets a chunk. Each size packs a set number of chunks into a pound — roughly fifteen for small whole, twelve for medium, ten for large — so the order weight is that piece count ÷ pieces-per-pound. Cost is simply the weight times the price. Harvest is a rule-of-thumb per piece: about 1.5 lb small, 2 medium, 2.5 large in good ground and a full season.
Why size matters: a whole small seed puts in one strong sprout and gets to harvest fastest with zero rot exposure, but takes more pounds per foot of row. Large cut potatoes deliver more pieces per pound — cheaper per foot — but every cut face is a wound the soil attacks if it is cold and wet, and a chunk with one weak eye is a hole in the row. Most extension guides recommend one- to two-ounce chunks with at least one eye, cured two days so the cut suberizes before planting.
Worked Example: A Fifty-Foot Run
- You have 50 ft of row and 12-inch in-row spacing planned.
- Pieces: ceil(50 × 12 ÷ 12) = 50 chunks in the row.
- At medium cut size: 50 ÷ 12 ≈ 4.2 lb of seed to order.
- At $6 per pound, that's about $25 of certified seed.
- Estimated harvest: 50 × 2 = 100 lb of table potatoes.
- Small whole seed for the same row would be 50 ÷ 15 = 3.4 lb but often yields less per piece.
- Cut only what you plant that day; chunks left over dry out or rot before the row is filled.
- Hill the row twice — once when sprouts are six inches and again two weeks later — and the yield estimate holds.
Pieces per Pound and Yield
Averages for certified seed in decent ground with a full season. Wet springs, poor hilling or heavy pest pressure pull both numbers down. Small whole seed costs more per row foot but skips the cutting, curing and rot risk entirely, while large cut pieces stretch a single pound the farthest.
| Seed size | Pieces per lb | Yield per piece |
|---|---|---|
| Small whole (egg) | 15 | 1.5 lb |
| Medium cut (tennis) | 12 | 2.0 lb |
| Large cut (baseball+) | 10 | 2.5 lb |
Key Terms
- Seed potato
- A whole or cut potato grown and sold specifically to plant — not a grocery spud, which is often sprout-suppressed.
- Eye
- A bud on the potato's surface that becomes the sprout; every cut chunk must carry at least one.
- Chitting
- Pre-sprouting seed in cool light for two weeks so plants emerge faster and more evenly.
- Hilling
- Drawing soil up around the stems mid-season to catch the tubers forming along the buried stalk.
- Curing
- Letting cut seed chunks dry for a couple of days so the cut face suberizes and does not rot on planting.
What This Means for the Spring Order
- Buy certified disease-free stock, always — volunteer potato viruses carried in grocery seed spread through the ground and stay there; the money the calculator saves you on price-per-pound is never worth it.
- Order in February, not April; the specialty fingerlings and storage varieties sell out by late winter and the leftover stock is whatever nobody wanted.
- Cut larger seed into one- to two-ounce chunks with at least one or two eyes each and let the cuts suberize two days before planting — this is the difference between a full row and a half-row of rotted seed in cold, wet soil.
- For small garden plots, buy whole small seed: it costs more per row-foot but eliminates the cutting, curing and rot risk entirely, and often produces a more uniform harvest earlier.
- Save the smallest, disease-free chunks from your own harvest for next year's seed line, and re-buy certified every third year so the seed stock does not drift toward degeneracy.
Common Mistakes & Fixes
- Ordering pounds of seed based on the size of the bed rather than the number of pieces the row actually holds, and ending up with three times what you can plant.
- Planting grocery-store potatoes as seed and being surprised by sprout-suppression or a virus load that ruins three seasons of soil.
- Cutting seed weeks ahead and letting the chunks dry or rot in a bucket instead of cutting the day of planting with a cured two-day window.
- Skipping the hilling step and harvesting a fifth of the yield the calculator promised, because the stolon and tubers spread upward into un-hilled air.
- Planting too early in cold, wet soil and losing half the pieces to seed rot before they ever break the surface.
When to Use This (and When Not To)
Use it before ordering spring seed so the pounds you buy actually match the row feet you have. It sizes certified seed for a conventional in-row planting; for straw-bale potatoes, container grow-bags or the upright-bale method, spacing and yield per piece are different enough that the numbers here will mislead. It is not the tool for planning how many pounds your family eats — for that use the feed-a-family planner, then bring the required row feet back here to convert them into a seed order.
Potato Seed Calculator: Frequently Asked Questions
How many seed potatoes do I need for a 40-foot row?
At 12-inch in-row spacing that is forty pieces. In medium cut seed at about twelve pieces per pound, that is roughly 3.3 lb of certified seed. Small whole seed takes less weight but costs more per pound, so the total is usually a wash.
Can I plant grocery-store potatoes instead of seed?
You can, but the harvest usually disappoints. Grocery potatoes are often treated to suppress sprouting and can carry viruses that stay in your soil for years. Certified seed is a few dollars more per row and is the reason the yield estimate in this calculator works at all.
How big should a cut seed piece be?
One to two ounces with at least one or two eyes. Smaller chunks sprout weak and rot easily; larger chunks waste seed. Let the cut face dry and suberize for a couple of days in a cool shaded spot before planting to prevent soil rot.
How many pounds of potatoes will one plant give?
Roughly five to ten pounds from a healthy seed chunk in good ground — the calculator uses 1.5–2.5 lb per piece as a conservative planning number because real gardens rarely deliver the top of the range. Hill twice, water evenly and you can honestly push toward the higher figure.
Should I chit or sprout seed before planting?
Yes, if your season is short. Two weeks in cool bright light ahead of the planting date gets stubby green sprouts started, so plants emerge days earlier and the whole harvest shifts forward a couple of weeks. Skip it if you are planting in a wet or very cold window — sprouts snap off easily in hard soil.
When should I order seed potatoes?
Order in late winter, in January or February, while the specialty and storage varieties are still available. By April the good stock is sold out at most regional suppliers, and the leftover is what nobody else wanted to plant.
Sources & Further Reading
- Growing Potatoes: Seed Selection, Cutting and Hilling — University of Minnesota Extension
- Certified Seed Potatoes for Home Gardeners — North Carolina State University Extension
- Potato Yields per Row and Storage Varieties — Penn State Extension
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