Balance every stream in minutes with smart checks. Compare inflow, outflow, and buildup across units. Export results to share with your team easily today.
This example uses totals over a period. Try it to see a consistency check.
| Case | Inflow (kg) | Outflow (kg) | Generation (kg) | Consumption (kg) | Initial (kg) | Final (kg) | Expected Accumulation (kg) |
|---|---|---|---|---|---|---|---|
| Reactor over 2 hours | 240 | 220 | 8 | 2 | 250 | 276 | 26 |
This calculator uses the standard total mass balance over a chosen time interval:
If the mass held inside the system is known at the start and end of the interval, accumulation can also be computed as:
In rate mode, the calculator converts rates to totals using: total = rate × time.
Mass balance is the first check engineers run on reactors, storage tanks, evaporators, dryers, distillation columns, and wastewater units. It validates metering, confirms whether a unit is accumulating material, and supports compliance reporting. In batch operations it helps reconcile charge, product, and losses; in continuous plants it helps quantify leaks, purge losses, and yield changes over shifts during commissioning and routine audits, too.
A correct balance starts by defining what is “inside” the system boundary: one vessel, a train of unit operations, or a site-wide process block. Then pick a basis that matches your measurements: per batch, per hour, or per day. Consistent units matter—keep everything in kilograms (or convert at entry) and treat inflows and outflows as positive magnitudes. Generation and consumption represent net creation or destruction inside the boundary, such as reaction stoichiometry or volatilization.
Many instruments report mass flow as kg/h, while inventory readings are snapshot masses. To compare them, convert to totals over the same interval: total = rate × time. Align start and end timestamps for the inventory with the metered period, especially when tanks are filled or drained near the boundary times. For short runs, even a 5‑minute offset can distort accumulation, because the inventory term changes faster than the average flow.
If you can compute accumulation both ways, the difference is a useful quality flag. A small mismatch (often within 1%) suggests reasonable consistency, but acceptable limits depend on measurement uncertainty. Typical Coriolis flow meters can be around 0.1–0.5% of reading in good conditions, while belt scales and level-to-mass conversions may be several percent. When mismatch is large, recheck density assumptions, unit conversions, sign conventions, and whether recycle streams were counted twice.
For multi-component problems, run separate balances on total mass and on key species (e.g., solvent, water, or impurity) to isolate where the error enters. Account for moisture changes, vented vapors, filter cake holdup, and sampling losses. In recycles, balance the overall system first, then individual units. Document assumptions so future shifts can reproduce the reconciliation.
Accumulation is the net change of mass held inside the chosen system boundary over the interval. It equals Final mass minus Initial mass, and should match the term balance when all inputs are correct.
Use rate mode when your measurements are in kg/h (or similar) and you have a defined time period. The calculator converts rates to totals using rate × time, then performs the balance.
To solve for inflow, outflow, generation, or consumption, the balance needs accumulation. Initial and final mass provide accumulation directly, which anchors the equation and prevents under-determined results.
It depends on measurement uncertainty. For well-instrumented liquid systems, ~1% can be reasonable. For solids handling or level-based inventories, several percent may be expected. Use the mismatch as a diagnostic, not a pass/fail rule.
Total mass is conserved, but within a boundary you may see net generation or consumption of a tracked species. Enter the net produced amount as Generation and the net consumed amount as Consumption for that species.
Yes. Sum all feed streams into Inflow and all product, vent, and purge streams into Outflow for the same time basis. Add internal Generation/Consumption only if you are tracking a specific component balance.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.