Disk Space Allocator (Partition Planner)
Plan disk partitions by percentage and see each one's size in GB/TB, with a visual bar and an over-allocation warning. Runs entirely in your browser.
Allocation
About this tool
Planning how to carve up a disk or volume is easier in percentages than in raw gigabytes, but you ultimately need the concrete sizes. This planner lets you set a total capacity and add as many named partitions as you like, each with a percentage of the whole; it instantly converts those percentages into actual sizes in your chosen unit and draws a proportional bar so the split is easy to see. It tracks how much remains unallocated and warns clearly if your partitions add up to more than 100% of the disk. It is handy for sketching a server's storage layout, dividing a NAS, or planning an LVM or cloud volume before you commit. The arithmetic is exact and runs entirely in your browser; nothing is saved or sent anywhere.
How to use it
- Set the total disk size and unit.
- Add or edit partitions, giving each a name and a percentage.
- Watch the bar and the per-partition sizes update live.
- Keep the total at or below 100% — the tool flags over-allocation — then copy the plan.
Frequently asked questions
- How are partition sizes calculated?
- Each partition size is its percentage of the total: size = (percent ÷ 100) × total capacity. A 30% partition of a 1000 GB disk is 300 GB. The unallocated remainder is 100% minus the sum of all partitions.
- What happens if my percentages exceed 100%?
- The tool shows an over-allocation warning and tells you by how much, in both percent and size. You cannot physically allocate more than the disk holds, so reduce one or more partitions until the total is 100% or less.
- Should I leave some space unallocated?
- Often yes. A small unallocated margin gives flexibility to grow a partition later, and some systems benefit from slack (for example, leaving headroom on SSDs can help wear-leveling). The planner shows the unallocated amount so you can decide deliberately.
- Does this use decimal (GB) or binary (GiB) sizes?
- It treats the total and the results in the same unit you pick, so the percentages are exact regardless. Be aware that drive manufacturers quote decimal GB (10⁹ bytes) while operating systems often report binary GiB (2³⁰ bytes), which is why a "1 TB" drive shows as ~931 GiB.
- Can I plan more than a few partitions?
- Yes — add as many as you need. Each gets its own color in the bar, and the totals and warnings update for any number of partitions.
- Is my plan saved or uploaded?
- No. It lives only in the page while open and is computed locally. Use the copy button to save the plan as text yourself.