The standard premium for a licensed California bail agent is 10% of the bail amount. If the court set bail at $20,000, the premium is $2,000. That is the figure, and you can work it out for any bail amount with the same arithmetic — the rate does not climb as the number gets bigger.
Where it comes from matters, because it is not a price a bondsman invents on the night. Every surety files its rates with the California Department of Insurance and has them approved, and an agent charges the approved rate. Ten per cent is the standard one. It is not the only one — approved rates below it exist for some circumstances — which is why this page says "standard" rather than "fixed". The court sets the bail amount itself long before a bail agent is involved.
The premium is a fee, not a deposit. It pays for carrying the whole bail amount on your behalf and it is earned once the bond is posted, so it does not come back at the end of the case. That is the single thing most first-time callers have wrong, and it is worth being blunt about: the money people expect to get back is cash bail, paid to the court in full and returned when the case closes — an arrangement that means finding the entire $20,000 yourself first. How a bail bond works as an instrument sets out the rest of what that premium buys.
What is genuinely variable is not the rate but how much has to clear before the bond is posted, and that is what the rest of this page is about. Bail Bond Central quotes the number in full before anything is signed, under CA Bail License #6015872, and there is no charge for the call, for finding someone in the county system, or for the quote itself. The general FAQ covers the questions that are not about money.