What percentage of this bar is complete?

The bar is complete by whatever the filled portion shows out of the full length. In general, progress bars use a 0–100 scale, so the percentage is:

complete=filled parttotal bar×100\text{complete}=\frac{\text{filled part}}{\text{total bar}}\times 100complete=total barfilled part​×100

If you share the bar image or the filled/total values, I can give you the exact percentage.