Planter Liner Size Calculator

Size liners for raised beds, pots, and boxes. Account for depth, taper, and overhang easily. Download CSV or PDF and cut liner accurately now.

Inputs

Choose the closest planter style.
Outputs follow the chosen unit.
Inside depth from rim to base.
Inside top length.
Inside top width.
Use for tapered planters.
Enter with bottom length.
Inside top diameter.
Extra material above rim for fastening.
Add for thick liners or sharp corners.
Typical: 5–15% for trimming and errors.
Optional cost estimate.
Choose a typical liner thickness.
Helps with practical guidance.
Reset

Example Data

Planter Type Inputs Overhang Waste Estimated Liner Sheet
Rectangular box 80 × 40 × 30 (cm) 5 cm 10% ~ (80 + 2×30 + 2×5) by (40 + 2×30 + 2×5)
Tapered planter Top 70 × 35, Bottom 60 × 25, Depth 28 (cm) 4 cm 12% Uses max(top,bottom) then adds depth and allowances
Circular pot Diameter 45, Depth 35 (cm) 6 cm 8% ~ (45 + 2×35 + 2×6) square sheet
Examples are simplified to show the method. Your results include small pleat allowance for cleaner fitting.

Formula Used

Rectangular / Tapered (sheet dimensions)
L = max(TopLength, BottomLength) + 2·Depth + 2·Overhang + 2·FoldAllowance
W = max(TopWidth, BottomWidth) + 2·Depth + 2·Overhang + 2·FoldAllowance
A small pleat factor is added when depth is large. This helps cover corner folds without coming up short.
Circular (sheet dimension)
SheetSide = Diameter + 2·Depth + 2·Overhang + 2·FoldAllowance
A gentle gather allowance is added to help tuck the liner neatly around the circumference.
Area and waste
Area(m²) = (L(cm) × W(cm)) / 10,000
AreaWithWaste = Area × (1 + Waste% / 100)
If you enter a cost per m², the calculator estimates the liner budget using the waste-adjusted area.

How to Use This Calculator

  1. Measure the inside top dimensions and the inside depth.
  2. If the planter tapers, also measure the inside bottom.
  3. Choose an overhang so you can staple, clamp, or tuck.
  4. Add fold allowance for thick liner and tight corners.
  5. Set a waste percentage for trimming and small mistakes.
  6. Press Calculate to see liner sheet size and area.
Tip: For drain holes, cut small X-shaped slits. Then seal edges with a grommet, patch, or compatible sealant, depending on liner material.

Purpose and Practical Fit

This calculator estimates the flat liner sheet needed to line planters before filling with soil. It supports box, tapered, and round containers, and it adds allowances so the liner can be folded neatly over the rim or fastened under a cap board. Accurate liner sizing reduces stretching, tearing, and messy patchwork during installation.

Measurement Inputs That Matter

Use inside measurements because the liner sits against interior faces. Enter top length and width for boxes, or diameter for round pots. Depth should be measured from the rim seating line to the base. For tapered planters, bottom dimensions improve accuracy by using the larger of top and bottom faces as the governing cut size.

Allowances for Overhang, Folds, and Waste

Overhang provides extra material above the rim for stapling, clamping, or tucking. Fold allowance helps when liners are thick or corners are sharp, where pleats consume material. Waste percentage covers trimming, drain penetrations, and handling errors. For simple shapes, 5% may suffice, while raised beds and heavy materials often need 10–15%.

Calculation Method and Output Use

The sheet dimension is computed by adding twice the depth plus allowances to the governing base dimension. A small pleat factor is included for deep planters to reduce shortage risk at corners or around circumference. Outputs include sheet length, sheet width, and area in square meters, plus an optional cost estimate when a unit price is provided.

Installation Notes for Durability

Dry-fit the liner first, then press it into corners and mark folds. Make small X-slits for drain holes and reinforce with patches or gaskets to prevent spreading. Avoid sharp fasteners directly on the liner; use battens or washers. For outdoor or water-holding planters, select UV-resistant material and increase overhang for secure anchoring. Label cuts, keep seams centered, and store remaining liner flat for future repairs later.

FAQs

How much overhang should I use?

Use 3–8 cm for small pots and 5–12 cm for raised beds. Increase it if you will fold over a rim, clamp under a batten, or expect soil to press hard against edges.

Why does the calculator add a pleat allowance?

Deep planters need folds at corners or gathers around curves. A small allowance helps the liner sit flat without tension, reducing the chance of tears, pinholes, or a liner that stops short.

Should I measure inside or outside dimensions?

Measure inside dimensions. The liner follows the interior walls and base, so inside measurements match the surface the liner must cover. Outside measurements can oversize the sheet and waste material.

What waste percentage is usually safe?

Use 5% for simple cuts and careful work. Use 10–15% for thick liners, tapered planters, drain penetrations, or when you want extra material for patching and reinforcement.

How should I cut drain holes?

Seat the liner first, then mark the hole locations. Cut small X-shaped slits, not large circles. Reinforce with a patch, gasket, or grommet so the opening does not spread over time.

Can this be used for water-holding planters?

Yes. Add more overhang, keep folds smooth, and choose durable pond-grade material. Water weight increases stress, so avoid sharp fasteners and protect edges with battens, washers, or protective strips.

Related Calculators

Pot volume calculatorPlanter volume calculatorContainer volume calculatorRound pot volume calculatorSquare pot volume calculatorTapered pot volume calculatorTapered planter volume calculatorRaised container volume calculatorHanging basket volume calculatorWindow box volume calculator

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.