Page Load Time Calculator (Size, Bandwidth, Latency)
Enter the page weight, connection speed and latency.
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Page Load Time Calculator (Size, Bandwidth, Latency) by TheCalcTools
How the Page Load Time Calculator (Size, Bandwidth, Latency) works
Load time is roughly transfer time (size × 8 ÷ bandwidth) plus latency (round-trip time × the number of sequential round trips for DNS, TCP and TLS set-up and dependent requests).
On mobile networks latency often dominates; cutting requests, using HTTP/2 or HTTP/3, a CDN and preconnect hints helps more than shaving bytes. Rendering and JavaScript time are extra.
The formula
Worked example
Using the default values shown in the calculator:
| Page weight (MB) | 2.4 |
|---|---|
| Connection speed (Mbps) | 20 |
| Round-trip time (ms) | 80 |
| Round trips (DNS, TLS, requests) | 8 |
- 2.4 MB at 20 Mbps takes 0.96 s to transfer plus 0.64 s of latency: about 1.60 s.
Result:
| Estimated load time (s) | 1.60 |
|---|---|
| Transfer time (s) | 0.96 |
| Latency time (s) | 0.64 |
| Main bottleneck | Page size (bandwidth) |
| Size for a 1-second load at this speed (KB) | 900 |
Frequently asked questions
Why is my fast connection still slow?
Latency: each round trip costs the same however fast the line, and pages often need several in sequence.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.