Plant Spacing Calculator

Estimate how many plants fit a planting area using your chosen center-to-center spacing. Compare square, rectangular-row and staggered arrangements, then add optional spare plants and a price per plant.

Calculate Your Plant Quantity

Use spacing suited to your plant and growing conditions. The calculator does not recommend spacing for a species.

Measure from the center of one plant to the center of the next, not between foliage edges.

Square spacing uses the same distance along and between rows.

Adds to the purchasing estimate, not the planting density. Leave blank for no spares.

Plant cost — optional

Uses the whole purchase quantity including any spares. Delivery, tax, planting labor and other materials are excluded. Currency selection does not convert prices.

Adding mulch around the planting area? Use the Mulch Calculator to estimate the separate material volume from coverage area and planned mulch depth.

PLAN SPACING BEFORE BUYING PLANTS

How to Use the Plant Spacing Calculator

Enter the usable planting area, choose an arrangement and apply your selected spacing to estimate plant quantity.

  1. Measure the usable planting area

    Enter length and width for a rectangular bed or select the known-area option. Exclude paths, paving and other spaces that will remain unplanted.

  2. Choose a planting arrangement

    Use a square grid for equal spacing in both directions. Choose rectangular rows for different in-row and between-row distances, or staggered triangular spacing for offset rows with equal nearest-neighbor distances.

  3. Enter center-to-center spacing

    Measure from one plant’s center to the next. For rectangular rows, also enter the distance between rows. Use spacing appropriate for your chosen plant and growing conditions.

  4. Review the estimate and optional spares

    Check the estimated plant quantity and planting density. Add an optional spare percentage and price per plant for a purchase estimate. Confirm actual planting positions around the bed edges before ordering.

Spares do not change spacing: The spare percentage increases the purchase quantity after the base plant estimate is rounded up. It does not add planting positions or reduce the selected spacing.

COMPARE PLANTING ARRANGEMENTS

Plant Spacing Calculation Examples

See how row spacing and staggered arrangements affect planting density. Spacing, spare percentages and prices below illustrate the calculations, not planting recommendations.

RECTANGULAR ROWS

Separate plant spacing from row spacing

Estimate plants for a 6 × 4 m area with 40 cm between plants in each row and 50 cm between rows. Add 5% spares.

Planting dimensions
6 × 4 m
Spacing within rows
40 cm
Distance between rows
50 cm
Spare plants
5%
Example price per plant
$2.50 USD
  1. Calculate the planting area

    6 × 4 = 24 m²

  2. Calculate area per plant

    40 cm = 0.40 m; 50 cm = 0.50 m
    0.40 × 0.50 = 0.20 m² per plant

  3. Estimate plants before spares

    24 ÷ 0.20 = 120 plants

  4. Include spares and calculate cost

    120 × 1.05 = 126 plants
    126 × $2.50 = $315.00 USD

ESTIMATED PURCHASE INCLUDING SPARES 126 plants · $315.00 USD

The base area estimate is 120 plants at 5 plants per square meter. The extra 6 plants are spares, not additional planting positions.

STAGGERED TRIANGULAR

Offset rows while keeping equal nearest spacing

Estimate plants for a 20 m² area using triangular spacing of 50 cm between nearest plant centers. Include 10% spares.

Known planting area
20 m²
Nearest plant spacing
50 cm
Calculated row separation
≈ 43.30 cm
Spare plants
10%
Arrangement
Offset alternate rows
  1. Convert the selected spacing

    50 ÷ 100 = 0.50 m

  2. Calculate triangular area per plant

    0.50² × √3 ÷ 2 ≈ 0.216506 m² per plant

  3. Estimate plants and round up

    20 ÷ (0.50² × √3 ÷ 2) ≈ 92.38
    Rounded up: 93 plants

  4. Apply spares to the whole base estimate

    93 × 1.10 = 102.3 → 103 plants

ESTIMATED PURCHASE INCLUDING SPARES 103 plants

This includes 10 spare plants above the rounded base estimate of 93. Actual planting positions depend on the bed boundary and setbacks.

Planting a circular bed?

Use the Circle Area Calculator to find the footprint from its radius or diameter. Subtract any unplanted inner area or paths, then enter the usable total using the known-area option.

Rounding sequence: The calculator first rounds the area-based plant estimate up. It then applies the spare percentage to that whole number and rounds the purchase quantity up again. Calculations use unrounded spacing and area values.

UNDERSTAND SPACING AND DENSITY

Plant Spacing Formulas & Density Table

Compare planting density at the same center-to-center spacing, then check how your chosen arrangement changes the estimated quantity.

Square and rectangular rows

Area per plant = in-row spacing × row spacing

Square planting uses the same spacing in both directions, so area per plant is spacing². Divide planting area by this value to estimate the number of plants.

Staggered triangular planting

Area per plant = spacing² × √3 ÷ 2

Alternate rows are offset by half the plant spacing. Row separation is approximately 0.866 × spacing, preserving equal distances between nearest neighbors.

Theoretical plants per square meter, rounded to two decimal places. No spare plants or boundary adjustments are included. Listed spacings are calculation examples, not recommendations for particular species.
Center-to-center spacing Square grid
plants / m²		 Triangular grid
plants / m²
20 cm 25.00 28.87
30 cm 11.11 12.83
40 cm 6.25 7.22
50 cm 4.00 4.62
60 cm 2.78 3.21
100 cm 1.00 1.15

At the same nearest-neighbor spacing, an ideal triangular grid has approximately 15.47% greater planting density than a square grid. Actual counts in a bounded bed depend on its dimensions, edge setbacks and row positions.

Measure between plant centers

Center-to-center spacing is the distance between planting positions. It is not the gap between leaves, the diameter of a pot or the distance from a plant to the bed edge.

Density does not give an exact boundary layout

Dividing area by area per plant estimates quantity across a repeating arrangement. It does not count individual rows or determine whether each planting position fits inside a narrow or irregular bed.

Calculate different planting groups separately

When groups use different spacing, divide the bed into their intended areas and calculate each group separately. Avoid applying several full-area estimates to the same space unless the planting plan requires it.

Keep spare plants outside the density calculation

The calculator rounds the base quantity up, applies your spare percentage and rounds the purchase quantity up again. Spares increase the order; they do not reduce the selected spacing.

Choose spacing for the plants you intend to grow

The calculator converts your selected spacing into a quantity estimate; it does not choose suitable spacing for a species. For perennial beds, the RHS perennial planting guide discusses spacing and checking the plant’s predicted spread. Use guidance relevant to your plant, variety and intended planting effect.

HELP WITH YOUR PLANTING PLAN

Frequently Asked Questions

Find answers about planting arrangements, center-to-center spacing, estimated quantities and spare plants.

How do I calculate how many plants I need?

Divide the usable planting area by the area allocated to one plant. For a square grid, area per plant is spacing × spacing. For rectangular rows, it is in-row spacing × distance between rows.

The Plant Spacing Calculator rounds this area-based estimate up to a whole plant. It can then add your selected spare percentage to estimate a purchase quantity.

What does center-to-center plant spacing mean?

It is the distance from the center of one planting position to the center of the next. It is not the empty gap between leaves or the distance between the outside edges of pots.

For example, 50 cm center-to-center spacing means neighboring plant centers are 50 cm apart. The calculator does not use foliage diameter to determine that distance.

What is the difference between square and rectangular rows?

A square grid uses equal distances along and between rows. With 40 cm spacing in both directions, each plant is allocated 0.40 × 0.40 = 0.16 m².

Rectangular rows allow different distances. With 40 cm between plants and 60 cm between rows, the allocation is 0.40 × 0.60 = 0.24 m² per plant.

How does staggered triangular spacing work?

Alternate rows are offset by half the selected plant spacing. The distance between rows is spacing × √3 ÷ 2, approximately 0.866 times the spacing.

This preserves equal distances between nearest neighbors. Simply shifting rows sideways while keeping row separation equal to plant spacing is a different arrangement from this calculator’s triangular option.

Does the result show the exact number that fits inside my bed?

No. It estimates quantity from area and planting density, then rounds up. It does not position individual plants or count complete rows.

Bed dimensions, narrow sections, edge setbacks, access paths and where rows start can change the number of actual planting positions. Check the physical layout before ordering.

Does the calculator recommend spacing for my plants?

No. You choose the spacing; the calculator uses that distance to estimate planting density and quantity.

Follow guidance appropriate to the species, variety, growing conditions and intended planting effect. Example spacings on this page demonstrate the arithmetic rather than recommending a distance for every plant.

How are spare plants calculated?

The calculator first rounds the base area estimate up. It then multiplies that whole number by 1 + spare percentage ÷ 100 and rounds the purchase quantity up again.

For example, a base estimate of 93 plants with 10% spares gives 102.3, rounded up to 103 plants to purchase. Spares do not change the spacing or add planting positions to the bed.

Can I calculate mixed planting areas or a single hedge row?

For separate planting groups with different spacing, calculate each group using its allocated area. Avoid assigning the same full bed area to multiple groups unless the planting plan specifically requires it.

A single hedge row needs a linear calculation based on its length, end setbacks and planting positions. This tool uses area-based density and does not provide an exact single-row hedge count.

PLAN YOUR PLANT PURCHASE

Turn Your Planting Area into a Quantity Estimate

Enter your area, arrangement and center-to-center spacing to estimate plant quantity. Add optional spares and a price per plant to plan your purchase.

Calculate Plant Quantity