How much water does a 4 meter round pond hold?

    Every cubic meter of pond water weighs one metric ton - and a 4 m round pond holds 6.3 of them. Enter shape, dimensions and depth to get volume, EPDM liner size, plant count and fish capacity.

    A round pond with a 4 meter diameter and a recommended depth of 1.2 m for fish holds a specific volume of water measured in thousands of liters. The EPDM liner needs to be larger than the pond itself - the formula adds twice the depth plus one meter of overlap on each side. Enter your exact dimensions below to see volume, liner size, plant count and fish capacity.

    Parameters

    Enter data for calculations

    Choose pond shape

    Diameter for round, length for others

    Width for rectangular or kidney shape

    Deeper = better for fish survival in winter

    Fish need a deeper pond

    EPDM avg: $5-10/m2

    Form progress0 / 4 fields

    💡 Fill in all required fields to unlock the calculate button

    Every cubic meter of pond water weighs one metric ton - here is what that means for your garden

    A modest 4 m round pond at 1.2 m depth holds 15,080 liters of water - that is 15 metric tons sitting in your garden. The EPDM liner to hold it measures 7.4 m x 7.4 m and costs around $383 at $7/m2. The calculator works out surface area, volume, liner dimensions, how many plants you need, and how many fish the pond can safely support.

    Four numbers that define your pond

    12.6 m2

    Surface area (4 m round)

    15,080 L

    Water volume (1.2 m deep)

    7.4 x 7.4 m

    EPDM liner needed

    75 fish

    Max capacity (5/m3)

    How to use the garden pond calculator - step by step

    1. Pond shape - round is simplest to build and calculate. Kidney-shaped looks most natural. Rectangular suits formal gardens.
    2. Length or diameter - the main dimension. A 3-4 m pond is a good starting point for most gardens.
    3. Width - only for rectangular and kidney shapes. Leave empty and the calculator defaults to 70% (rectangular) or 60% (kidney) of length.
    4. Depth - 0.5 m for a water feature, 0.8 m for plants, 1.0-1.5 m for fish. Fish need at least 1 m to survive winter.
    5. Fish? - if yes, the calculator shows maximum stocking density (5 fish per m3) and warns if depth is too shallow.
    6. Liner price - enter your local EPDM price per m2 to see total liner cost. US average: $5-10/m2.

    Pond volume and liner size by dimensions

    Pond (round) Surface (m2) Volume at 1 m Volume at 1.2 m Liner size (1.2 m) Max fish
    2 m diameter 3.1 3,140 L 3,770 L 5.4 x 5.4 m 18
    3 m diameter 7.1 7,070 L 8,480 L 6.4 x 6.4 m 42
    4 m diameter 12.6 12,570 L 15,080 L 7.4 x 7.4 m 75
    5 m diameter 19.6 19,630 L 23,560 L 8.4 x 8.4 m 117
    6 m diameter 28.3 28,270 L 33,930 L 9.4 x 9.4 m 169

    Fish capacity at 5 fish per m3 (1.2 m depth). Liner = diameter + 2x depth + 1 m overlap.

    Did you know?

    A 4 m round pond weighs as much as 3 cars. At 15,080 liters (15 metric tons), it is heavier than most SUVs combined. The ground beneath must be compact and level.
    EPDM rubber liner lasts 30-50 years. PVC lasts 10-15 years but costs half as much. Over a 30-year period, EPDM is cheaper because you never replace it.
    Water lilies need exactly 80 cm of depth. Too shallow and the leaves burn. Too deep and they cannot reach the surface. The 0.8 m depth option is designed for them.
    A goldfish produces 1 gram of ammonia per day. With 75 fish in a 15 m3 pond, the pump must cycle the entire volume twice per hour to keep water safe. That is 30,000 liters per hour.

    Practical examples

    Small decorative pond, round, 2 m, 0.5 m deep: Surface: 3.1 m2. Volume: 1,570 L. Liner: 4.0 x 4.0 m (16 m2). No fish - too shallow. Plants: 9. Liner cost: ~$112.
    Mid-size fish pond, round, 3 m, 1.2 m deep: Surface: 7.1 m2. Volume: 8,480 L. Liner: 6.4 x 6.4 m (41 m2). Max fish: 42. Plants: 21. Liner cost: ~$287.
    Kidney-shaped, 5 x 3 m, 1.0 m deep: Surface: 12.8 m2. Volume: 12,750 L. Liner: 8.0 x 6.0 m (48 m2). Max fish: 63. Plants: 38. Liner cost: ~$336.
    Large rectangular, 6 x 4 m, 1.5 m deep: Surface: 24.0 m2. Volume: 36,000 L. Liner: 10.0 x 8.0 m (80 m2). Max fish: 180. Plants: 72. Liner cost: ~$560.
    Tiny water feature, round, 1.5 m, 0.5 m deep: Surface: 1.8 m2. Volume: 880 L. Liner: 3.5 x 3.5 m (12.3 m2). No fish. Plants: 5. Liner cost: ~$86.

    EPDM vs PVC liner comparison

    Feature EPDM (rubber) PVC
    Lifespan 30-50 years 10-15 years
    Price per m2 $5-10 $2-5
    UV resistance Excellent Degrades after 10 yrs
    Flexibility Very flexible, even in cold Stiffens in cold weather
    Fish safe Yes (non-toxic) Yes (if fish-grade)
    30-year cost (50 m2) $350 (1 liner) $350-500 (2-3 liners)

    FAQ

    How deep should a fish pond be?
    Minimum 1.0 m for fish to survive winter in temperate climates. Recommended: 1.2-1.5 m. The deeper zone stays above freezing even when the surface freezes, giving fish a safe refuge. Koi ponds should be at least 1.5 m.
    How many fish can a pond hold?
    The safe rule is 5 fish per cubic meter of water. A 3 m round pond at 1.2 m depth holds 8.5 m3 = about 42 fish. Overstocking causes ammonia spikes and kills fish. Start with fewer and add gradually.
    How do I calculate EPDM liner size?
    Liner length = pond length + (2 x depth) + 1 m overlap. Liner width = pond width + (2 x depth) + 1 m overlap. For a 4 m round pond at 1.2 m deep: 4 + 2.4 + 1 = 7.4 m in both directions. Always round up to the nearest available roll size.
    How much does it cost to build a garden pond?
    For a mid-size 3 m round pond (1.2 m deep): EPDM liner $287, pump $120-200, filter $80-150, plants (21 plants) $126-252, fish $40-200. Total: roughly $650-900 DIY. Professional installation adds $500-1,500.
    Do I need a pump for a garden pond?
    Yes, unless it is a very small decorative water feature with no fish. The pump circulates and filters the water, preventing stagnation, algae bloom and mosquito breeding. Minimum flow: 2x the pond volume per hour. A 15 m3 pond needs a pump rated at 30,000 L/hr.
    Can I keep koi in a garden pond?
    Koi need at least 1.5 m depth and 1,000 liters per fish (more than goldfish). A 4 m round pond at 1.5 m holds 18,850 L, enough for 15-18 koi. They also need higher filtration capacity and produce more waste than goldfish.

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    See also

    2 Meter Round Pond - Volume, Liner Size and Fish Capacity3 Meter Round Pond - Volume, Liner Size and Fish Capacity5 Meter Round Pond - Volume, Liner Size and Fish Capacity6 Meter Round Pond - Volume, Liner Size and Fish Capacity

    Calculator verified by the LiczGrupa.pl team

    Content, formulas and results have been reviewed for accuracy and relevance by our team of specialists.

    Natalia Skrzek

    Reviewed by: Natalia Skrzek

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