The number of feet multiplied by 144 equals inches.
How many gallons of rainwater my roof.
Multiply the area of your roof by the amount of rainfall you wish to calculate for.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall.
So multiply 623 gallons by the number of surface square feet of your roof.
An inch of rainfall on a square foot of surface area yields 623 gallons.
1 500 x 144 216 000 multiply those 216 000 square inches by the rainfall.
1 of rain on 1 000 sf roof will yield 623 gallons.
This means that each square foot captures about 62 gallons per inch of rain.
If your average rainfall was 25 inches year your annual collection potential is 1 120 x 25 28 000 gallons year.
Take the dimensions of the footprint of your roof and convert them to inches.
So each inch of rain on your roof will have 763 gallons of water going down your downspouts.
We ll fine tune it for the real world but let s first do a quick reality check before going any further.
Roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.
Rainwater can be collected from the roofs using the rain water harvesting method.
One inch of rain falling on 1000 sq ft of roof will deposit 623 gallons of water.
Roof area m2 x precipitation amount mm amount collected liters.
You might even want to know how many baths you could get from your rainstorm.
For example if you have a roof that measures 1 500 square feet that equals 216 000 square inches.
When you look at the numbers it s surprising how much water you can collect every time it rains.
How much will your roof be able to capture.
Rainwater collection calculation formulas and equations.
Simply take your roof s square footage and multiply by 62.
To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above.
Consider your roof s size and harvesting capacity.
Either way you would like to know how much rain has fallen how many gallons have come down from the skies onto your roof yard block or town.
Rainwater collection calculator in gallons.
So for each inch of rainfall your roof could collect 1 246 gallons of rainwater.
The answer is about 623 gallons.
Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water.
The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area.
That is the theoretical best case outcome for this scenario.
For every 1 inch of rain and 1 000 square feet of roof you capture about 620 gallons of water.
In the form below choose an area s and a rainfall amount to see how many gallons of water fell from the sky onto that area.
In our example it would be 623 x 2 000 which equals 1 246.