Backup window & bandwidth calculator
How long for the first backup? Does the daily incremental fit within 24 h? Enter your volume and uplink — the result is instant.
In one sentence
The first backup transfers the whole volume (except on Proxmox VE → PBS direct, where dedup cuts the data up front), then the daily incremental only moves what changed. Duration depends on the effective rate = min(your uplink, the ingestion ceiling) × the real network efficiency. This tool estimates both durations and tells you whether a 24 h RPO holds.
Indicative estimate — not a promise
Real throughput depends on chunking, hashing, the protocol and machine load. No number here is guaranteed. The default efficiency (50 %) is anchored to our 1 TB field case: 876 GB transferred in 20h30, i.e. ≈ 47 % of a 200 Mbps link. Use it to size and compare scenarios, not as an SLA.
Your parameters
Observed on our 1 TB field case (≈ 47 %).
Used to estimate the daily incremental.
Estimated results
min(200, 200) × 50 %
Transferred: 1.00 TB
0.05 TB/day changed
24 h RPO achievable — the incremental fits within a daily backup.
How to read the result
RPO ≠ RTO
RPO (Recovery Point Objective) is the maximum acceptable data loss: a daily incremental that fits within 24 h gives you a 24 h RPO. RTO (Recovery Time Objective) measures the restore time — it depends on download bandwidth and the target, not on this send window.
The first backup is the bottleneck
It moves the most data. Via the Gateway it ships the whole volume; via Proxmox VE → PBS dedup cuts it up front. If the estimate runs into several days, a local seed is often the right answer. To pick the right path, see the “choose your backup method” guide.
Where the default efficiency (50 %) comes from
On a 1 TB Windows server, our first PBS backup transferred 876 GB in 20h30, i.e. ≈ 47 % of a 200 Mbps link (75 % deduplicated chunks, 57 % end-to-end savings). We round conservatively to 50 % as the default efficiency. Read the case study →
Go further
This calculator sizes the send window. To design the end-to-end path — protocol, ingestion, PBS protection — these resources complete the estimate.
Unsure about your backup window?
We measure your real throughput, pick the right path (Gateway or PVE → PBS) and size the seed. 15-minute technical chat, no commitment.