The two transactions being compared
First estimate the consolidation size: transaction overhead plus the original input count multiplied by input vbytes, plus the new output size. Multiply that total by the current fee rate.
For the later spend, the model compares spending the original inputs with spending one consolidated input of the same input type. The estimated saved size is the number of inputs removed multiplied by input vbytes. Apply the assumed future fee rate to that saving.
A higher future fee is an assumption
A positive net saving means the future input-fee saving exceeds the consolidation fee under your inputs. It is not a forecast that future fees will reach that level. Try a lower future fee rate and a higher current fee rate to see how sensitive the result is.
For example, many small inputs may be expensive to spend when fees rise. But if only one of those inputs would have been used later, the all-inputs comparison overstates the saving. Change the scenario to match the intended spend.
Privacy and wallet structure still matter
Consolidation can link coins in ways that reveal more about common ownership. It can also remove the flexibility of keeping separate outputs. This arithmetic tool does not measure those trade-offs. Actual wallet fee estimation should account for the final transaction format, integer fee rounding and whether the assumed new output can be spent with the input size you supplied.
Questions about this tool
Does this scan my UTXOs?
No. You enter the count and size assumptions manually. No address, key or wallet connection is required.
When is the comparison most relevant?
When the same original inputs would otherwise be spent together in one future payment and the new output uses the assumed input type.