Reservoir volume calculator
Estimate a rectangular reservoir’s working volume from inside dimensions.
Use the result as a starting point.
Enter measured values, check the units, and keep the assumptions beside the answer. This tool supports a growing decision; it does not replace a calibrated meter, a product label, or observation of the crop.
Why it matters: A realistic working volume makes label-rate calculations repeatable and leaves room for roots or an air gap where needed.
Use working depth, not the container’s maximum height.
How to use this tool
Use working dimensions to estimate how much solution is actually available for dosing, top-offs, and reservoir planning.
- Enter the inside length, width, and liquid depth, then choose inches or centimeters.
- Enter the values, check the units, and select Calculate.
- Read the result as a planning estimate, then compare it with the crop and system.
Formula or reference method
Rectangular volume = length x width x working depth. The result is converted to liters and US gallons.
Worked example
A 26 x 18 x 8 inch working volume is about 61.35 L or 16.21 US gallons.
Understanding the result
Use working liquid volume for label-rate calculations, not the container shell rating.
Assumptions and limits
Net pots, roots, headspace, media, and equipment displace liquid. The calculator assumes a rectangular interior.
Common mistakes
Do not use outside dimensions or the maximum container height when the reservoir is only partly filled.