Rain Tank Sizer

Rain Tank Sizer is an offline calculator designed to help estimate rooftop rainwater collection and select a suitable storage tank size.

Enter basic information about your roof, local rainfall, water demand, and storage preferences to calculate how much rainwater may be collected and stored.

Main features

• Estimate rainwater collection from a rooftop area
• Calculate potential water yield using rainfall data
• Compare different tank capacities
• Estimate how long stored water may cover your expected usage
• Adjust roof area, runoff efficiency, rainfall, and consumption values
• Review calculation results in a clear and structured format
• Recalculate results instantly after changing input values
• Use the app without registration or an internet connection

Offline and private

Rain Tank Sizer works locally on your device. Calculation data is not uploaded to a server, and no account is required.

Useful for early planning

The app can help homeowners, gardeners, builders, and property managers make preliminary estimates when planning a rainwater harvesting system.

Important

Results are estimates based on the values entered by the user. Actual rainwater collection can vary depending on rainfall patterns, roof material, gutter efficiency, water loss, tank configuration, and local conditions.

Rain Tank Sizer does not replace professional engineering advice, plumbing calculations, structural assessments, or local building and water regulations.