Hi Kate,
Don't forget that you also need to cover costs including stamp duty. A generous rule of thumb is 6% for all costs.
So you need at least 5% for the bank and 6% for costs. So your savings/equity/FHOG need to be 11% of the value of the property.
Or, as Simon suggests, 26% if you want to avoid LMI costs.
Cheers, Medine