Salary Increase & Promotion Calculator

What this tool does

CM8-335 tests whether a pay rise or a promotion is actually worth taking. It compares your package before and after — base, the bonus you really expect, the employer's pension contribution and benefits — against the hours the job will really take, the leave you will really get and any change to the commute. It then answers three questions the offer letter never does: is this an increase in real terms, what happens to what you earn an hour, and what rate are you being paid for the additional time.

Everything runs inside this single file: no account, no upload, no network request. Your salary and your private view of a promotion never leave your computer.

The marginal rate, and why it is the important number

A promotion is a transaction. You are selling additional hours and additional responsibility, and being paid a specific amount for them. The marginal rate is that price: the increase divided by the extra hours a year the new job takes.

Comparing it against what you already earn an hour is uncomfortable and clarifying in equal measure. A sixteen per cent rise that adds nine hours a week is roughly four hundred extra hours a year — and if the increase is six thousand, those hours are being bought at about fifteen an hour by somebody who is already paying you more than twenty for the ones they have. Framed as a percentage it is a good rise. Framed as a transaction it is a discount, and the discount is on your time.

This does not make it a bad decision. Promotions buy position, scope, the next job and sometimes work that is simply more interesting, and none of that is on this page. But the trade should be made deliberately. The specific failure this tool exists to prevent is accepting a step that leaves you worse off an hour without ever noticing, and then being unable to explain a year later why the rise did not feel like one.

Nominal and real

An increase below inflation is a pay cut described as a rise, and the sample data includes one because almost every annual review round contains one. The tool shows both figures side by side and computes the real increase properly — by deflating the nominal one rather than subtracting the inflation rate, which is close enough at small numbers and materially wrong at large ones.

The stacked chart splits every increase into the part that merely keeps you level with prices and the part that is a genuine improvement. It is a small piece of arithmetic that changes how a review letter reads.

What counts as the package

Base salary, the bonus you actually expect rather than the one at target, the employer's pension contribution as a percentage of base, and other benefits valued at what they would cost you to buy.

The pension line deserves attention because it moves quietly. A promotion that raises base by five per cent while dropping the employer contribution from seven per cent to four is close to no increase at all, and nothing in the letter will say so. Equally, a modest regrade that adds two points of pension can be worth more than a bigger-looking rise — as the sample data shows.

Estimating the hours after — the honest way

Every ranking in this tool turns on hours a week after, and it is the number people fill in most optimistically. Nobody accepting a promotion believes they will be the one who cannot get out of the building.

Do not use the contract. Do not use what the manager offering it says. Ask the person currently doing the job what time they leave, how often they work at weekends, and whether they take their leave. If the role is new, find the nearest equivalent. Where you genuinely cannot find out, add at least a fifth to your current hours for any role with people reporting into it, and note the assumption — the number of reports is the best available predictor of how the hours column will turn out, which is the only reason it is on the form.

The break-even test

The second summary table asks the question the other way round: how many extra hours could this increase absorb before it stops being worth anything? The increase over the standstill position, divided by what you earn an hour today, gives the number of hours it buys. Compare that with the hours the move actually adds.

A comfortable margin means the offer survives the hours running over, which they usually do. A negative margin means the rise was spent before you started. This framing is often more persuasive in a conversation than a percentage, because it is specific: "this increase covers about a hundred and eighty extra hours a year, and the role adds four hundred" is difficult to argue with.

Which baseline to compare against

By default the marginal rate and the break-even test compare the new package against today's package uplifted by inflation, not today's package as it stands. That is the honest baseline: staying where you are and receiving nothing makes you worse off, so the real question is whether the offer beats the standstill, not whether it beats zero.

Switch to the flat comparison in Settings when you want the nominal figures — for instance when the rise is being awarded on top of a separate cost-of-living increase, so inflation has already been dealt with elsewhere and counting it twice would understate the offer.

Tax

No tax of any kind is applied unless you enter an effective rate yourself, because this tool is used everywhere and a wrong assumption would be worse than none. Enter your own effective rate — total deductions divided by gross, not your marginal rate — on every row if you want the after-tax picture.

One point is worth knowing where a rise crosses a threshold: the effective rate after the rise is higher than before, so entering the higher figure is the conservative choice. If a large part of an increase disappears in deductions, that is exactly the case where the after-tax marginal rate is worth calculating properly, because the hours are unchanged and the reward is smaller than it looks.

Using it in the conversation

The break-even framing is a better negotiating instrument than a number you would like, because it is about the role rather than about you. It also points at the cheapest things an employer can move: a day a week at home, extra leave, or two points of pension often cost far less than the equivalent salary, sit outside the pay-review approval process, and shift this calculation considerably. Salary is usually the single hardest thing on the list to change.

If a promotion is declined, model the pay rise you would accept instead before the conversation rather than after it. The sample data includes exactly that row.

What it deliberately ignores

Career trajectory, what you would learn, the people, security, how the title reads on your next application, and whether the work is any good. Every one of those can be worth more than the entire arithmetic here. A promotion with a poor marginal rate can be an excellent decision — and one taken with the numbers in front of you is a decision rather than a drift.

The formulas

FAQ

The marginal rate is blank. The move adds no extra hours, so there is no marginal rate — a rise for the same job is simply better, and the tool has nothing clever to add.

The marginal rate is negative. The new package is below the standstill baseline: after inflation you would be going backwards, and doing more hours for the privilege.

Should I count the phone at weekends? Yes. Add a realistic weekly figure to the hours after. Being available is not the same as working, but it is not free either, and a role where it happens every weekend is not a thirty-nine-hour job.

My promotion is worse an hour. Should I refuse it? Not necessarily — but you now know what you are buying and what it costs, which puts you in a position to ask for something that closes the gap. A day a week at home or five days of leave frequently does.

Why is the real increase not just the rise minus inflation? Because that approximation drifts as the numbers grow. Deflating properly is exact, and at the sort of figures a promotion involves the difference is visible.

Saving your work

Moves, settings and the report header are written to this browser's local storage as you type. That storage belongs to one browser on one computer.

Treat Export .json as the real save, which Import .json restores anywhere. Export CSV gives you the comparison for spreadsheet work. Reset asks twice, then erases everything. There is no undo.

The backup contains your salary, an offer made to you and your candid opinion of it. Keep it off shared drives and out of work accounts.

Accuracy & disclaimer

The most useful figure here depends on a number nobody can verify in advance: how many hours the new job will actually take. People accepting promotions underestimate it almost without exception.

A low marginal rate is not by itself a reason to refuse. Promotions buy position, scope and future options, and those can be worth far more than this arithmetic. What the tool prevents is the specific mistake of taking a step that leaves you worse off an hour without noticing. No tax is applied unless you enter a rate yourself, and nothing here is financial, tax or career advice.