Is everything split 50/50 in a divorce?
No. Nine states start from a presumption of equal division; the rest divide marital property fairly, which is deliberately not the same word as equally. And in both systems it is the overall total that gets balanced, not each individual asset cut in half.
Two ideas do most of the work here, and neither of them requires knowing your state's specifics to understand.
The two systems
Community property states treat what you acquired during the marriage as belonging to both of you equally, and generally divide that pool down the middle. There are nine: Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin. A few other states allow couples to opt into something similar.
Equitable distribution states, which is everywhere else, divide marital property fairly given the circumstances. Fair often lands near half, and it does not have to. Courts weigh things like the length of the marriage, each spouse's income and earning capacity, contributions to the marriage including raising children and running a household, age and health, and who the children will live with.
So a 60/40 or 70/30 division is entirely possible in most of the country. It is less common in the nine, but the nine are not uniform either. California directs courts to divide equally. Nevada does too, but a Nevada judge can divide unevenly on finding a compelling reason to, and has to write that reason down, which is the opening if your spouse gambled away, hid, or burned through marital money. Texas divides community property in whatever way is "just and right" and Washington in whatever is "just and equitable," and disproportionate divisions are ordinary in both.
The part almost everyone misreads
It is the marital estate that gets divided, not each asset.
Nobody saws the house in half or splits every account down the middle. The exercise is to value what there is, decide the proportion, and then allocate whole things until the totals come out right. One spouse keeps the house and the other takes more of the retirement. One keeps the business and the other is balanced with everything else.
Which is why "who gets the house" is really a question about the total, and why an asset you care about is often gettable if you are willing to give up value elsewhere.
What is not in the pool at all
All of the below assumes no enforceable prenup - where one exists, it can redraw the whole map. In most states only marital property gets divided, and what you owned before the marriage, inherited, or were given individually is generally separate property that stays yours. But a real minority of states, among them Washington, Indiana, Massachusetts, Connecticut, New Hampshire, and Vermont, put all property into the divisible pot regardless of when or how it was acquired, and treat its origin as a reason to divide unevenly rather than a reason to exclude it. That list is not a closed one, so do not conclude that what you brought in is safe simply because your state is not named on it. Which kind of state you are in changes the whole question.
That distinction does more to determine outcomes than the fifty-fifty question does, and it has its own traps. Marital versus separate property covers it, including the way separate property quietly becomes marital.
Two things that shift the arithmetic
Debts get divided too, and people forget them when they imagine the split. The pool is what you own minus what you owe.
After-tax value is what matters. A dollar in a retirement account and a dollar in savings are not worth the same, because one has tax waiting on it. A settlement that looks even on a spreadsheet can be meaningfully uneven once tax is applied, and that is one of the clearest cases for spending money on a financial professional.
What this means for you
Knowing whether you are in one of the nine tells you what the starting presumption is. It does not tell you the outcome, because the size and character of the pool matter more than the ratio applied to it.
The useful preparation is the same either way: know what exists, know what is arguably separate, and know what things are worth after tax. Gathering your documents is the unglamorous work that makes all of it possible.
Which system your state uses, and what factors a court weighs within it, are state law, and the nine-state list above is the conventional one but a few states have their own variations. Confirm what applies where you live before relying on any ratio.