Tool
Plant spacing calculator
See how many plants a bed holds at a given spacing — useful before you sow or buy seed.
Your result
About 32 plants
- Bed length (m)
- Bed width (m)
- Spacing (cm)
What this calculator does
It estimates how many plants a rectangular bed will hold if you space them on a simple grid. Use it to sanity-check a seed order, plan how much to sow, or decide how far apart to thin seedlings. It answers a planning question, not a growing one: spacing affects airflow, light and how much each plant competes for water and nutrients.
When to use it
- Deciding how much seed to buy for a fixed bed.
- Planning how many seedlings to raise indoors.
- Working out thinning distances once plants are up.
How to use it
- Measure the bed you actually want to plant — inside edges, not the whole plot.
- Find the spacing on the seed packet or seed catalogue.
- Enter all three above; the result is the number of planting positions.
Worked example
A bed 2.4 m by 1.2 m, planted at 30 cm spacing, gives 8 positions along the length and 4 across — about 32 plants. If the packet says 20 cm instead, you would fit 12 by 6, or roughly 72 plants from the same bed.
Typical spacings
| Crop | Typical spacing |
|---|---|
| Lettuce | 20–30 cm |
| Carrot | 5–8 cm |
| Onion sets | 10 cm |
| Tomato (indeterminate) | 45–60 cm |
| Beans (bush) | 15–20 cm |
| Courgette | 60–90 cm |
Spacing varies by variety and growing style; always check the packet. Close spacing gives more plants but smaller, hungrier ones.
Limitations
- Grid estimate. Beds sown in offset (staggered) rows fit slightly more than a square grid allows.
- Paths and edges are not counted. Exclude them from the dimensions or you will overestimate.
- It ignores growing habit. Trailing or sprawling crops need far more room than their planting distance suggests.
Frequently asked questions
Should I use the spacing on the seed packet?
Yes — it is the best default. This tool just multiplies it over your bed dimensions.
Why do I get fewer plants than expected?
The calculation rounds down at each edge, so the last part-row is not counted. That is deliberate — plants near an edge often get left out anyway.
Does closer spacing increase yield?
Up to a point, then it reduces size and increases disease risk through poor airflow. Follow the packet unless you are deliberately growing cut-and-come-again crops.
Related guides
Sources and research notes
Spacing figures are typical ranges from horticultural guidance; final spacing always follows your own seed packet and conditions.