Guide · Billing
How storage is measured: the P95 method
Entropia bills your data room storage on sustained use, not on transient peaks. Here's exactly how the P95 (95th percentile) method works, why we use it, and what it means for your invoice.
Updated June 2026·5 min read
What we measure
We measure the total volume of data stored in your data room: every file, across every folder. Rather than reading that figure once and calling it a month, Entropia samples it several times a day.
Sampling frequently means we capture how your storage actually evolves: the steady baseline you rely on day to day, and the brief moments when it climbs, for example when you stage a large batch of files before an upload.
The P95 method
At the end of each month, we don't bill the highest figure we ever recorded. We apply the P95, or 95th percentile, method. All the readings taken during the month are ranked from lowest to highest, and we keep the value that was exceeded only 5% of the time. Everything in that top 5%, the brief spikes, is set aside.
- 1
Sample
Storage is read several times a day, all month long, building a detailed picture of real usage.
- 2
Rank
At month end, every reading is sorted from the lowest value to the highest.
- 3
Keep the P95
We keep the value exceeded only 5% of the time. That figure, your P95, is what you're billed.
Each dot is a storage reading. They follow the data room's gradually rising baseline. The two highlighted peaks, short-lived bulk uploads, fall in the top 5% and are excluded. The dashed line is your P95: the volume you're actually billed.
Why the 95th percentile
Billing on the peak would mean paying for a one-off bulk upload you removed hours later. P95 avoids that: it captures your real, sustained footprint while ignoring the transient peaks that don't reflect how much storage you genuinely rely on. It's the same percentile approach the cloud industry has long used to meter bandwidth.
12 GB
Overcharges you for a single one-off spike.
4.2 GB
Reflects sustained use and ignores short-lived peaks. Fair and predictable.
A worked example
Imagine a data room whose storage grows gradually from about 3 GB to 4 GB over the month. Twice, a large batch of files is staged for upload, briefly pushing it up to 12 GB before the extra files are removed hours later.
Ranked from lowest to highest, the picture is clear: the two highlighted bars on the right are the brief peaks. The P95 line sits just above that everyday range: that's the billed value.
Over that month the peak was 12 GB, but the P95 is 4.2 GB. You're billed on 4.2 GB, your real, sustained footprint, not the 12 GB spike from a bulk upload you no longer keep.
What it means for your invoice
The practical upshot is simple, and more favourable than how data rooms usually bill:
- You're never billed for a transient spike. A peak has to last more than 5% of the month, roughly 36 hours, before it moves your P95.
- Staging large uploads or preparing downloads won't inflate your bill if you remove them soon after.
- You pay month by month, for the storage you actually used that month. Most data rooms charge every GB across the data room's entire booked term, so a document added in the final month is billed as if it had been stored from the start. With Entropia, it isn't.
- The figure on your invoice tracks the storage you sustainably rely on, so it's predictable from one month to the next.
- Storage is assessed per data room, so each data room's billed volume reflects its own usage.
FAQ
If I upload a large batch and delete it the next day, will I pay for it?
No. A one-day spike falls in the top 5% of readings that P95 excludes. Only if elevated storage is sustained, present more than 5% of the month (roughly 36 hours), will it raise your P95.
How often is storage sampled?
Several times a day, throughout the month. Frequent sampling is what lets the P95 distinguish a genuine baseline from a short-lived peak.
What counts toward the measured volume?
The total volume of data stored in the data room: all files across every folder at the moment each reading is taken.
Do other data rooms bill storage this way?
Rarely. The percentile method itself is a long-established cloud and networking standard, but among data room vendors it's uncommon. Most charge every GB across the data room's entire booked term, so a file added late costs the same as one stored from day one, and many bill on peak usage. Entropia's P95, billed month by month on real usage, is deliberately more favourable.