Rainwater Harvest Calculator

Estimate how much rainwater your roof can collect with this easy Rainwater Harvest Calculator. Enter roof size, rainfall and efficiency to get annual litres and cubic metres instantly.

How Much Water Is Falling on Your Roof?

More Than You Think… Most people don’t realise that their roof is basically a giant water-collecting machine, quietly wasting thousands of litres every year. With this Rainwater Harvest Calculator, you can finally find out just how much precious rain you could store, save and put to good use.

What This Tool Helps You Do

• See how much water your roof can collect in a full year
• Estimate litres and cubic metres instantly
• Plan barrels, tanks or full rainwater systems
• Save money on water bills while helping the planet

It is simple, quick and surprisingly satisfying, especially when you realise your roof is sitting on a goldmine of free water.

Final Word

Thanks for using the Rainwater Harvest Calculator. If you enjoyed this one, share it, save it or show it to that neighbour who refuses to buy a water butt but complains about his bills.

If you want more tools, have suggestions or want something added, drop a comment. I’m always building the next great garden helper.