DevCalc Logo
DevCalc
Construction Calculator

Water Tank Capacity Calculator

Calculate rectangular or cylindrical water tank capacity in litres, cubic metres, and US gallons from internal dimensions.

Enter the tank's internal dimensions, choose its shape, and optionally set a usable fill level. The result shows gross and usable storage plus an indicative household supply duration.

Tank Dimensions

Use clear internal dimensions, not the outside size of the tank.

Volume and duration are planning estimates. Confirm structural, plumbing, waterproofing, and local requirements separately.

Compare Similar Calculators

House Construction Cost Calculator

Estimate house construction cost in India from built-up area, city tier, quality, and floors. Review per-square-foot rates plus material and labour shares.

View

Concrete Calculator

Calculate concrete volume, cement bags, sand quantity, aggregate quantity, and material costs for slabs, foundations, columns, beams, and construction projects.

View

Staircase Calculator

Calculate staircase steps, riser height, tread depth, total run, stair angle, and stringer length from your floor-to-floor height and available space.

View

More Construction Calculators

AAC Block CalculatorStaircase CalculatorHouse Construction Cost CalculatorBrick CalculatorCement CalculatorConcrete CalculatorTile CalculatorRebar Cutting Length CalculatorPaint CalculatorStamp Duty Calculator

How the Water Tank Capacity Calculator Works

1

Choose the Tank Shape

Select a rectangular tank or a vertical cylindrical tank.

2

Enter Internal Dimensions

Use clear inside dimensions so wall thickness is not counted as stored water.

3

Set the Usable Fill

Allow for freeboard or a level below the tank's full height if needed.

4

Review Capacity

See gross capacity, usable litres, gallons, and estimated household duration.

Water Tank Capacity Formula

Rectangular: L × W × H; Cylindrical: π × r² × H; Litres = cubic metres × 1,000

The calculator converts every entered dimension to metres before finding volume. For a rectangular tank it multiplies internal length, width, and height. For a cylindrical tank it uses half the internal diameter as the radius. Usable capacity is gross volume multiplied by the chosen fill percentage.

Example Calculation

Input: Rectangular tank: 6 ft × 4 ft × 4 ft at 90% usable fill

Output: Gross capacity is about 2,718 litres and usable capacity is about 2,446 litres.

Common Uses

  • • Sizing an overhead household tank
  • • Checking an underground sump
  • • Converting tank dimensions to litres
  • • Estimating backup-water duration

Questions about this calculator

Use internal clear dimensions. External dimensions include the wall thickness and therefore overstate the volume available for water.

A tank may not be filled to the brim because of overflow level, freeboard, pipe position, sediment allowance, or operating practice. Adjust the fill percentage to reflect the actual maximum water level.

One cubic metre equals exactly 1,000 litres. One cubic foot is approximately 28.3168 litres.

No. It estimates liquid volume only. A qualified professional should design the structure, reinforcement, foundation, waterproofing, access, overflow, and plumbing.

How to Calculate Water Tank Capacity

Measure the clear space inside the tank. A rectangular tank uses length × width × water height. A round vertical tank uses π × radius² × water height. After converting the volume to cubic metres, multiply by 1,000 to obtain litres.

Gross Capacity and Usable Storage

Catalogue capacity often describes the tank at its full geometric volume. In practice the overflow, inlet arrangement, freeboard and minimum pump level can reduce the water you can use. The fill control lets you plan with a more realistic operating volume.

Planning Household Storage

Daily use varies substantially with household size, fixtures and habits. The duration result is only a planning comparison based on the daily litres per person you enter. Confirm local supply conditions and obtain professional advice for structural and plumbing design.

Learn more

Latest helpful articles

Recent guides and verified updates selected for this calculator.

View all articles

Governance and Policy

HAL, NCAP, and ASI Sign MoU for Heritage Site Conservation

The Press Information Bureau announced on October 13, 2026, that Hindustan Aeronautics Limited (HAL), the National Culture Fund (NCAP), and the Archaeological Survey of India (ASI) signed a Memorandum of Agreement (MoA) for heritage site conservation. The collaboration focuses on three key sites: Hampi in Karnataka, the Taj Mahal in Agra, Uttar Pradesh, and Bekal Fort in Kerala. HAL has approved ₹23.60 crore in financial assistance for the financial years 2026-27 to 2028-29. The projects aim to preserve and improve tourist facilities at these UNESCO and heritage sites, promoting sustainable heritage tourism. ASI will provide technical guidance to ensure conservation principles are followed.

3 min read

Mining and Energy

Offshore Mineral Block Auction Compliance Deadlines and Process Details

The Ministry of Mines conducted a stakeholders' conference on October 13, 2026 regarding the auction of two offshore mineral blocks - Sevel Rise-01 and West Sevel Ridge-01 in the Andaman Sea. The Invitation for Tender (NIT) was issued on October 1, 2026. Key dates include: Pre-Bid Conference on November 4, 2026, last date for queries November 13, 2026, tender documents available until December 21, 2026, and bid submission deadline of December 28, 2026. The auction operates under the Offshore Areas Mineral (Development and Regulation) Act, 2002 and the Offshore Areas Mineral (Auction) Rules, 2024. Two composite licenses for polymetallic nodules and crusts containing nickel, cobalt, copper and manganese are up for auction covering a total area of 1,632 square kilometers.

3 min read

Weather Services

MoU Signed Between Ministry of Rural Development and National RUDSETI Academy to Strengthen Rural Skill Development

On 12 October 2026, the Ministry of Rural Development signed a Memorandum of Understanding (MoU) with the National RUDSETI Academy (NAR Academy). The purpose of the agreement was to strengthen training standards and institutional capacity. The agreement was formalised in the presence of Secretary (Rural Development) Shri Rohit Kansal. The MoU was exchanged between Joint Secretary (Rural Skill) Shri S. Shashikumar, representing the Ministry, and Director General Shri Raju N. kori, representing the National RUDSETI Academy. The event was reported by the Press Information Bureau (PIB) Delhi and documented in a press release dated 12 OCT 2026.

3 min read

Embed this calculator

Add the Water Tank Capacity Calculator to your website for free. Keep the attribution link in the widget intact.

The embedded route is excluded from search indexing to prevent duplicate-content pages. The main calculator page remains the canonical source.

AS

Written & maintained by Aditya Singh

Aditya Singh is a software engineer and the founder of DevCalc, based in Uttar Pradesh, India. He builds and maintains every calculator on this site using documented formulas, worked examples, and clearly stated limitations, with careful attention to accuracy. Read more about the author →