The short answer is that fifteen to twenty per cent of the service price is the normal range in the United States, with twenty being unremarkable for good work and more than that reserved for something exceptional.
The longer answer is that several common situations are genuinely ambiguous, and most of the awkwardness comes from those rather than from the percentage.
The ordinary case
On the service price, before tax. Twenty per cent is a safe default and nobody will think twice about fifteen.
Per person who worked on you. If one person shampooed and another cut, both did work. Splitting a single tip between them is normal, and most salons will do it for you if you say so at the desk.
Not on retail. Buying shampoo is a purchase, not a service. No tip is expected on the product.
The situations people actually find awkward
The owner cut your hair. The old convention was that you do not tip an owner. That convention is largely gone and most owners now accept tips. Tipping is safe; not tipping is also not rude.
You had a discount or a promotion. Tip on the original price if you can. The work was the same amount of work.
The service went wrong and is being fixed. You do not tip on a correction of a mistake. If the same person is fixing it well and graciously, tipping on the original service is a kind thing to do and not an expectation.
You are on a package or a membership. The service still happened. Tip on the normal price of the service, not on the zero you paid today.
Card or cash? Cash reaches the person faster and in full. Card is recorded and appears in their pay — which some staff prefer for exactly that reason. Either is fine, and the idea that cash is meaningfully better for the recipient is less true than it used to be.
There is a service charge on the bill. Ask what it is. A service charge is not automatically a tip — it may go to the business — and the distinction has real consequences. We wrote it up in service charge vs tip: why the label matters.
What salon owners should know about this
If you run a salon, two things in the above cause you problems and both are fixable.
Ambiguity at the desk slows checkout and embarrasses people. A client who does not know whether to tip, how much, or to whom, resolves it by doing nothing and leaving quickly. Clear prompts at the point of payment — sensible default percentages, and an easy way to split between two staff — remove the hesitation entirely.
Your prompts change behaviour measurably. The default options on the screen are the single biggest lever on tip rates in your salon. That is worth setting deliberately rather than accepting whatever your card reader shipped with. Set them too high and you generate resentment; leave them off and you leave money your staff would have received.
The parts that are not etiquette
Some of this is law rather than custom, and it is worth owners knowing the difference.
Tips are taxable income and have to be reported.
Who may share in a tip pool is regulated. The rules on who can and cannot participate are specific, and a pool including the wrong people is not a policy choice. Tip pooling rules covers it.
Whether the card fee can come off a tip has rules that vary. The card fee on a tip and who pays it goes through it.
A service charge is not a tip unless it is distributed as one, and calling it a gratuity does not settle that.
None of those are things a point-of-sale system decides — it will faithfully record an arrangement that is not permitted. They are worth settling before configuring anything.
The one-line version
Fifteen to twenty per cent on the service, before tax, split between everyone who worked on you, on the pre-discount price, and ask what a service charge actually is.