Load Time Estimator
Estimate transfer time for your page weight across slow 3G, fast 3G, 4G and cable, with a budget verdict.
Estimate how long your page weight takes to load on real connections.
Page weight
700 KB
Acceptable, but there is room to trim.
Transfer time
- Slow 3G
- 14.00s
- Fast 3G
- 3.50s
- 4G
- 0.62s
Total page weight: 700 KB
Slow 3G 14.00s
Fast 3G 3.50s
4G 0.62s
Cable 0.19s
// Estimates transfer time only, excluding latency and processing.About the load time estimator
Page weight has a direct relationship with load time on slow connections, and most of the world is not on fibre. A one megabyte page that loads instantly on your laptop takes twenty seconds on slow 3G.
JavaScript is worth watching more closely than images, because bytes of script cost parse and execution time on top of transfer, and that lands on the main thread.
How to use it
- 1Enter the size of each asset type.
- 2Read the total and the verdict against a sensible budget.
- 3Check transfer time across the connection speeds.
- 4Trim the largest contributor first.
Questions
What is a reasonable page weight?
Under a megabyte total is a solid target, and under 500KB is excellent. Above two megabytes you will lose users on mobile connections.
Why is JavaScript called out separately?
Because it costs twice: transfer time, then parse and execution on the main thread. 300KB of script blocks interaction far longer than 300KB of images.
Are these estimates exact?
No. They cover transfer time only, excluding latency, server response and rendering. Treat them as a relative guide.