Internal length: enter a value greater than zero.
How it works
Display litres = internal length × width × water depth ÷ 1,000. Net system litres = display litres − entered displacement + operating sump litres. A 100 × 40 × 40 cm water space holds 160 L before displacement; subtracting 20 L and adding 30 L of net sump water gives 170 L.
What to measure
External dimensions include glass and do not describe the water space. Measure the operating water level, and exclude freshwater top-up reservoirs. Displacement is an input you estimate or measure, not a fixed percentage assumed by this tool. Do not add rear filtration water twice if your measured footprint already includes it.
Measure and document your net system volume →
Use the result
Save the estimated volume on this browser, then use it in the saltwater planner. Keep a note of how you estimated displacement; a precise-looking decimal does not make the underlying measurements exact.
Plan saltwater batches · Estimate ownership cost · Keep your tank records