Pond Liner Size Calculator: Liner, Volume and Pump Flow
Work out the liner size for a garden pond from its length, width, depth and edge overlap. Also get a water volume estimate, a planting shelf allowance and a pump flow. Runs in your browser.
Your measurements stay in this browser. Nothing is uploaded or sent to a server. The formulas are rules of thumb marked UNSOURCED.
The tool failed to load. Please reload the page.
Report a problem or suggest an improvement
Nothing is sent until you press Send. Your measurements are included only if you tick the box, and you can see the full report below first.
When to use this
- You are digging a garden pond and need to know how big a liner to buy.
- You want a rough number of gallons or litres to choose a pump or treatments.
- You plan a planting shelf and want to see how it changes the volume.
How to use
- Choose feet or metres and pick the shape of the pond.
- Type the length and width at the widest point, the deepest point and the overlap you want on each edge.
- If you plan a planting shelf, type its width and depth. Otherwise leave it blank.
- Press Work out liner size. Read the liner size, the rounded buying size, the volume and the pump flow, and look at the cross-section.
Examples
- 10 ft by 6 ft, 2 ft deep: With 1 ft of overlap on each edge the liner is 10 + 2 x 2 + 2 x 1 = 16 ft long and 6 + 2 x 2 + 2 x 1 = 12 ft wide, 192 square feet. A plain rectangular box of that size holds 120 cubic feet, about 898 US gallons.
- The same pond with a 1 ft planting shelf: A shelf 1 ft wide and 1 ft deep removes 28 square feet of 1 ft of depth, so the volume falls to 92 cubic feet, about 688 gallons. The liner size does not change.
Understanding the result
The liner has to cover the pond across the top, down both walls and across the bottom, plus the overlap. That is the pond size plus twice the depth plus twice the overlap, in each direction. The tool then rounds up to a whole foot or half metre. Volume is length x width x depth less what the shelf takes up, scaled by a shape factor. The pump flow is the volume times the number of turnovers per hour, rounded up.
Limitations
- The formulas are rules of thumb marked UNSOURCED, not a liner maker's figures. Steep, uneven or rocky walls, deep pockets and waterfalls need extra liner.
- Volume of an irregular pond uses a rough 70 percent factor and may be off by a lot. For stocking fish or dosing treatments, measure the real volume with a meter or by filling.
- Pump flow ignores lift height, hose length and filters. Check the pump maker's flow curve at your real head height.
- Liner is sold in set sizes that vary by maker, so the rounded size is only a guide. The tool does not know any shop's stock.
FAQ
How do I work out the size of a pond liner?
Add the length, twice the deepest depth and twice the edge overlap for the liner length. Do the same with the width for the liner width. This tool does the sums and rounds the result up.
How much overlap should a pond liner have?
About 1 ft (0.3 m) on each edge is a commonly quoted allowance, enough to bury under the edge stones. It is an UNSOURCED rule of thumb, so change the number if your design needs more.
Does a planting shelf change the liner size?
No. The liner still has to follow the walls and the shelf, and the total distance across is the same. The shelf lowers the volume of water.
How big a pump do I need for my pond?
A common starting point is a pump that moves the whole pond volume once an hour, so a 900 gallon pond wants about 900 gph. Real needs depend on fish, filters, waterfalls and the lift height, so check the pump maker's data.
Are my measurements sent anywhere?
No. The sums run in your browser. Nothing you type is uploaded or sent to a server.
Related tools
- Fencing
Post and Footing Concrete Calculator: How Many Bags for Your Holes
Count the concrete bags and gravel for fence post or deck footing holes. Pick up your fence or deck plan, set hole size and depth, get a buy list and a drawing. Runs in your browser.
- Landscaping
Retaining Wall Block Calculator: Blocks, Caps, Base and Drainage Stone
Enter wall length, height and block size. Get blocks, caps, base gravel, drainage stone and drain pipe in one buy list, with a course-by-course profile drawing. Feet or metres. Runs in your browser.
- Fencing
Deck and Fence Stain Calculator: How Many Gallons from Your Plan
Turn a deck or fence plan into the area to stain and the gallons to buy: tops, edges, railing, stairs, pickets on both sides, posts and rails, with coats and a range. Runs in your browser.
- Landscaping
Paver Calculator: How Many Pavers, plus Base Stone and Sand for a Patio
Count the pavers for a patio, plus base stone, bedding sand, joint sand and edge restraint, layer by layer. Add waste and see a purchase list in tons or tonnes. Feet or metres. Runs in your browser.
More in Home & DIY
- Decking
Deck Board Calculator: How Many Boards, and Which Lengths to Buy
Enter your deck size and get a board buy list by length, a cut plan with staggered joints, the layout drawn to scale, joist and screw counts. Feet or metres. Runs in your browser.
- Fencing
Fence Picket and Post Calculator: Pickets, Posts, Rails and Concrete
Plan a fence run by run: posts, pickets, rails cut from stock lengths, concrete bags and a drawing of every run with gates. Feet or metres. Runs in your browser, nothing is uploaded.
- Walls
Wallpaper Calculator: How Many Rolls, with a Strip-by-Strip Plan
Enter your walls, doors and windows and the roll size and pattern repeat. Get the rolls to buy, every strip drawn on each wall, and a cut plan for each roll. Feet or metres. Runs in your browser.
- Tiling
Tile Calculator with Grout and Thinset: How Much Should You Buy?
Enter the surface, tile size and joint width. Get tiles with waste, boxes, grout bags and thinset bags in one buy list, plus a to-scale layout drawing. Feet or metres. Runs in your browser.