The plan total, the difference, and the break-even
The commission plan’s total is its base salary plus the expected sales volume multiplied by the commission rate. The difference is that total minus the guaranteed salary: positive means the commission offer pays more at the volume you entered, negative means the salary does. The break-even is the volume where the two land on the same number, which is the salary minus the base, divided by the rate.
Three money fields feed that arithmetic - the guaranteed salary, the commission base and the expected sales - and each is held between $0 and $1 trillion so an address-bar value cannot push the page into nonsense. The rate itself is clamped to 0%-100%.
The scenario table is separate from the break-even line. It runs seven fixed volumes - $0, $100,000, $150,000, $200,000, $250,000, $300,000 and $400,000 - so the crossing point is rarely a row on the table. The exact break-even is printed as its own stat, which is why the page can answer "how much do I have to sell" without asking you to interpolate a table.
The expected volume is the whole uncertainty
Every other input here is a contract term you can read in an offer letter. The expected sales figure is a guess about the future, and the page treats it as one: it is printed as the assumption behind the hero number, not as a forecast the site endorses.
That distinction runs through the whole comparison. A plan that beats the salary at your target but loses to it in a slow year is not a wrong answer - it is the actual shape of the offer. The table makes the shape visible because it starts at zero sales, where the commission plan pays only the base, and runs up to a strong year, where the commission dominates.
A tie is defined the way the page prints it: any difference under fifty cents rounds to the same whole dollar, so the hero reports the two plans as matching exactly and pushes the decision onto risk rather than pay. That is a deliberate reading of whole-dollar output, not a rounding accident.
What the page cannot know
It cannot weigh the non-financial terms: benefits, retirement match, quota culture, territory quality, or whether commission is paid monthly, quarterly, or only after the customer pays. Those often decide the job more than a few thousand dollars of expected pay, and none of them are inputs here.
It also assumes one flat rate on all sales. Real plans staircase, accelerate above quota, carry a draw, split credit between reps, or cap the upside, and every one of those designs bends the curve the page draws. The arithmetic is exact for the model it runs; the model is simpler than the plan document.
One edge case is handled explicitly rather than left to print an infinity. At a 0% commission rate no amount of volume closes the gap, so the break-even stat reads "never at this rate" and a warning note says the only thing doing any work is the base salary. If that base already matches or beats the salary, the answer is a statement about the base, not about sales.
What the comparison is really testing
A guaranteed salary is a horizontal line: the same money in a bad quarter and a good one. A commission plan is a line with a slope, so the decision turns on the volume you can hold when the pipeline is thin, not the volume you hit in your best month.
The break-even is where those two lines cross, and the distance from your expected volume to that crossing is the margin for error the offer gives you. At the default numbers - a $60,000 salary against a $40,000 base and 10% - the crossing sits at $200,000 of sales, and the expected $250,000 leaves $50,000 of cushion before the salary plan is ahead again.
None of this prices the guarantee itself. Certainty has value that a difference of a few thousand dollars does not capture, because the salary plan also survives the month where nothing closes. A plan that only wins above your realistic number is a bet rather than a raise, and the table is there so the size of that bet is visible before you sign. An estimate, not a return, and not tax advice.
Danfio