How to measure your pond
For a more accurate liner size, follow the pond’s slopes and floor with a long rope, strong thread or measuring tape.
Recommended: measure along the pond’s surface
Many ponds have sloping sides and a bottom that is shorter and narrower than the top. Measuring the actual surface follows the shape the liner must cover.
- 1Length: lay a long, non-stretch rope or strong thread from one top edge, down the slope, across the floor and up the opposite slope to the other top edge. Keep it against the surface, without pulling it tight across dips.
- 2Mark both top-edge points on the rope. Lay it out straight and measure between the marks with a tape, in sections if needed. A long flexible measuring tape can follow the same route directly.
- 3Repeat across the width. Check several routes in each direction, including the deepest areas, and keep the longest measurement for each direction.
- 4Add extra liner at both ends of each measurement for anchoring, including the route to and through your trench and any tail. Agree this allowance with your installer.
These measurements already include the slopes and floor. Do not add depth again. To price the final sheet size, choose “Cover / sheet” in the calculator and enter the length and width including anchoring allowance.
Work out my priceFor curved, stepped or irregular ponds, send a sketch, photos and measurements before ordering. The rectangular calculator cannot decide the fit or seam layout for you.
Alternative: a quick calculator estimate
For a quick calculator estimate, measure the top length, top width and deepest point in feet. For a closer fit on sloping sides, use the rope method in the full guide.
- 1Length: across the top, from edge to edge, on the longer side.
- 2Width: across the top on the shorter side.
- 3Depth: from the top edge down to the deepest point.
Before you measure
- Use a non-stretch rope, strong thread or a long flexible measuring tape. Pacing it out with your feet is not accurate enough.
- Finish digging first. Measure the pond as it will be, not as you plan it.
- If the sides are uneven, use the longest length and the widest width.
- Remove stones and roots from the walls. They can puncture the liner.
Quick sheet-size estimate
Sheet length = length + (2 × depth) + 3 ft Sheet width = width + (2 × depth) + 3 ft
This formula does not account for slopes or a smaller pond bottom, so it can give a larger sheet than needed. It includes 1.5 ft extra per edge for anchoring. Check your actual trench layout before ordering.
Example: for a pond 40 × 30 ft and 6 ft deep, the formula estimates a 55 × 45 ft sheet.
The water-capacity tool estimates storage only. Changing its bottom measurements does not change the quoted liner size. Use surface measurements for the sheet; have the installer confirm slopes, anchoring and drainage for your site.
Watch the 32-second measuring guide
A diagram explainer, not footage of a customer pond or the supplied material. English and Hindi captions are available. Read the written measuring steps too.
The 40 × 30 ft pond, 6 ft depth and 1.5 ft edge allowance are examples. Confirm the actual surface route and trench plan for your pond.
Plan the trench and overflow
Water capacity, extra liner and drainage do different jobs. Work them out before the sheet is made.
How water storage is calculated
Straight walls: length × width × water depth × 28.3168 = litres. Water depth is the total depth minus the gap to the overflow.
Sloping sides: volume = water depth ÷ 6 × (bottom area + 4 × halfway area + waterline area). Use areas at the actual water level, not the full pond rim. Multiply cubic feet by 28.3168 for litres.
Example: a straight-sided 40 × 30 ft pond, 6 ft deep, with the overflow 1 ft below the rim stores about 1,69,900 litres at 5 ft water depth. Sloping sides reduce this amount.
How much water will it hold?When does it overflow?
Flow starts when water reaches the outlet inlet or spillway crest. Place it below the rim and send the water to a protected discharge route so it does not wash away the bank. Keep the outlet clear.
Leave a vertical gap between the design high-water level and the top of the bank. This freeboard helps keep waves and rising water from washing over the bank. The normal overflow level alone does not set the highest storm water level.
Pipe diameter or spillway width depends on the rainfall, land draining into the pond, outlet slope and expected flow. A local irrigation technician should size it from those details.
What about the anchor trench?
Burying and compacting soil over the liner in an anchor trench helps resist wind lift and liner movement. It does not add to the pond’s water capacity. The installer should choose its position and size for the soil, bank and liner.
It holds the liner edge in place. The quote includes 1.5 ft of extra liner per edge; that is a sheet allowance, not the trench depth or width.
Calculate the trench & see why it helps
This calculation uses a continuous rectangular trench outside the pond rim, with vertical trench walls. The liner goes down, across the base, back up the far wall and then extends as a tail. Use your installer’s measurements; there is no standard size that suits every pond.
Enter 0 if none.
Enter 0 if none.
Enter the trench measurements to see how much to dig and how much extra liner is needed.
See the trench formula
Extra liner per edge = setback + (2 × trench depth) + trench width + tail.
Soil volume = trench centre length × trench width × trench depth. Centre length = 2 × (pond length + pond width) + 8 × setback + 4 × trench width.
Calculation & planning references
Common pond sizes: formula estimates
These are quick formula examples, not a cutting plan for a sloping or irregular pond. Open a size to check its estimated price with current rates and allowance.
| Pond (L × W × depth) | Estimated sheet | Area |
|---|---|---|
| 20 × 15 × 4 ft | 31 × 26 ft | 806 sq ft |
| 30 × 20 × 5 ft | 43 × 33 ft | 1,419 sq ft |
| 40 × 30 × 6 ft | 55 × 45 ft | 2,475 sq ft |
| 50 × 40 × 8 ft | 69 × 59 ft | 4,071 sq ft |
| 60 × 60 × 10 ft | 83 × 83 ft | 6,889 sq ft |
| 100 × 80 × 12 ft | 127 × 107 ft | 13,589 sq ft |
Have your final sheet measurements?
Enter the length and width after adding your anchoring allowance. Keep Cover / sheet selected for rope measurements. Pond liner mode is only for an estimate from the pond’s top size and depth.
See all sheet pricesYour price
An example size is filled in. Change it to your measurements.
Size of the sheet you need
Your price
₹4,350
Sheet price. Delivery extra.
- Sheet size
- 20 × 30 ft
- Area
- 600 sq ft
- Weight
- ≈ 12 kg
- Tarpaulin @ ₹7.25/ sq ft
- ₹4,350
Collect free from our godown in Chettukuzhy, Idukki at an agreed time, or check transport to your pincode. Confirm the carrier, freight and total with us before paying.
Check delivery before giving an address
Only the pincode is needed for this estimate.
Preparation usually takes 2–4 days after size confirmation. Courier transit is additional. Confirm packing, carrier acceptance and the final charge with us before paying.
The order form checks delivery again for the final size. No name or full address is needed here.
Send the size first, without filling the order form. We confirm the material, fit and delivery before payment.