Filesystem Allocation and Slack Calculator
Calculate allocated blocks and internal slack for a list of logical file sizes and a chosen allocation unit.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Round each file separately to whole blocks before summing the allocation.
Allocated bytes=Σ ceil(file bytes/block bytes)×block bytes
Worked example
Files of 1,4096,4097,10000 bytes use 28672 bytes with 4096-byte blocks.
Assumptions and input details
Nonnegative whole byte sizes, zero-byte files consume zero data blocks. Excludes metadata, directories, compression, sparse allocation, deduplication and filesystem-specific reservations.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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