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Volume and mass reconciliation

Liquid inventory balance calculator

Compare a simple book inventory with a measured closing inventory for the same liquid. Keep every volume on the same US-gallon and temperature basis, then use the matching density to express the difference in pounds.

Enter your values

Result

Results are based only on the inputs and assumptions shown here. Nothing you enter is sent or saved.

Formula: expected closing = starting + receipts − withdrawals; difference = measured closing − expected closing; lb difference = gallon difference × density

Worked example

Starting with 1,000 US gal, receiving 500 and withdrawing 400 gives an expected 1,100 US gal. A measured 1,090 US gal is 10 gal below that figure: −80 lb at an explicit 8 lb/US gal.

Keep one interval and one volume basis

The receipts and withdrawals must cover the interval between the starting and closing readings. Use one liquid, US gallons, and comparable temperature conditions. Temperature-corrected volumes cannot be mixed with observed volumes unless they are first brought to a common basis.

Read the sign

A negative result means measured inventory is below the simple book balance; positive means it is above. EPA’s inventory-control worksheet uses the same end-minus-book arithmetic. This small calculator does not implement that publication’s full procedures, thresholds or any regulatory test.

A difference does not identify a cause

Measurement resolution, timing, unrecorded transfers, temperature changes or physical loss can affect the balance. This arithmetic alone cannot diagnose a leak. Density converts the signed volume discrepancy to mass only under the stated common-liquid and common-basis assumptions. When expected closing volume is zero, the percentage is left uncalculated.

Explore the related calculation

For a different starting point, try the reference-temperature volume calculator or return to the main calculator. Browse the complete tool directory for this site.

Reference and corrections

The definitions and assumptions above follow these sources; the examples and calculator arithmetic are original to this page.

Found a problem? Email contact@gallonstopounds.org.