Price Increase Impact Calculator

What this tool does

CM8-337 models a price increase across a range and answers the question that actually decides it: how much volume can we afford to lose before we are worse off than we are now? It works line by line, so a single across-the-board percentage can be tested against products with very different margins, and it shows the effect on contribution rather than revenue.

Everything runs inside this single file — no account, no upload, no network request — which matters when the input is your unit costs and the output is your pricing strategy.

The break-even volume loss

This is the number worth taking away from the whole exercise, and it is a hard fact rather than an opinion. Given a price, a variable cost and an increase, there is exactly one volume loss at which total contribution is unchanged.

It is calculated from unit contribution, not from price. Raising a price by five per cent does not let you lose five per cent of volume — it usually lets you lose a great deal more, because every unit you keep now carries a bigger contribution. On a product priced at 42.50 with a variable cost of 31.20, a five per cent increase lifts unit contribution from 11.30 to 13.43, and you could lose almost sixteen per cent of the volume before standing still.

Most pricing arguments are conducted without this figure, which is why they are usually arguments about nerve rather than about numbers.

Why thin margins can absorb more

The relationship is counter-intuitive and worth internalising: the thinner the margin, the more volume a price rise can afford to lose.

A commodity line priced at 8.90 with a cost of 7.95 has a unit contribution of 0.95. A five per cent increase adds 0.45 to the price — nearly half as much again on the contribution — so it could lose around a third of its volume and still stand still. The premium line with a 39% margin, by contrast, can only afford to lose about eleven per cent.

The practical consequence is that the products people are most nervous about repricing are frequently the ones with the most room, and the ones they reprice confidently have the least. The tool shows both, side by side, so the nerve follows the arithmetic.

Contribution, not revenue

Revenue is shown because people ask for it. Contribution is what the decision rests on, because it is what pays for the fixed costs and everything after them.

A price rise that adds revenue and loses contribution is entirely possible — it happens whenever costs move faster than the price does — and a business tracking only revenue will call that a success for as long as it takes the year-end accounts to arrive.

Put only genuinely variable costs in the unit cost field: materials, bought-in parts, carriage, commission, direct labour where it truly varies with volume. Loading overhead into it inflates the apparent break-even loss and makes a marginal increase look safe.

Modelling cost inflation at the same time

Most price rises are a response to cost rises, so the tool lets you apply a change in unit variable cost across every line at once. This is what keeps it honest: if your costs rose six per cent and you raise prices five, contribution falls even with no volume lost at all, and the tool will say so plainly rather than congratulating you on the increase.

It also exposes lines where cost inflation has already eaten the margin. Where the affordable loss comes out at zero or below, the increase does not even restore the position you were in — that is the "cannot work" verdict, and it is a signal to look at cost or specification rather than price.

Getting the two inputs right

Price must be the price actually achieved after discounts, rebates and settlement terms, not the list price. Using list price is the commonest way this model flatters a decision, because the discount is exactly the part of the margin that is already gone.

Expected volume loss is the soft number, and the tool is deliberately relaxed about it. If you have no evidence, leave it at zero and read the affordable-loss column instead: "we can lose sixteen per cent" is a fact you can act on, where "we will lose three per cent" is a hope. The alternatives column exists only to make you look at the guess again — a commodity bought by tender and a specification-led product with no substitute should never carry the same number.

Contracted volume

The share of a line under fixed-price agreement does not change the arithmetic, but it changes what you can actually collect. An increase applied to a line that is eighty per cent contracted delivers a fifth of the benefit this period and the rest whenever those contracts come round.

The summary table shows how much of your revenue is locked. It is often the answer to why last year's price rise did not show up in the accounts.

Modelling a price cut

Enter a negative increase. The same logic applies in reverse, and it is sobering: the break-even figure becomes the volume you must gain, and it is almost always more than anyone expects. Cutting the price of a line with a 25% margin by ten per cent requires around two-thirds more volume simply to stand still. Very few markets deliver that.

Where the model breaks down

• Unit variable cost is assumed constant. If losing volume costs you a purchasing tier, or leaves a machine half-loaded, the cost per unit rises as volume falls and the real break-even is worse than shown.
• Lines are treated independently. Customers buy ranges. Losing a commodity line can take the profitable spares with it, and no line-by-line model sees that.
• Loss is modelled as a proportion. Where a line is one customer, the honest position is a probability of losing all of it, which behaves very differently from an average — the sample data includes exactly this case and says so.
• It says nothing about competitor response, or about timing. A rise announced badly can lose customers a well-handled larger rise would not.

The formulas

FAQ

Why does a 5% rise let me lose 16% of volume? Because the rise lands entirely on contribution. Five per cent of the price is a much larger percentage of the margin, and the margin is what you are protecting.

The affordable loss is negative. Your cost increase is larger than your price increase, so unit contribution has fallen. No volume outcome makes that better; the increase is not big enough.

Should I use gross margin or contribution margin? Contribution — price less genuinely variable cost. Gross margin usually carries some absorbed overhead, which understates the room you have.

How do I handle a rebate paid at the year end? Deduct it from the price, not from the cost. It is a discount that arrives late.

Can I model different increases on different lines? Yes — that is the point of doing it line by line, and a single across-the-board percentage is almost never the best answer once you can see the affordable-loss column.

Saving your work

Lines, settings and the report header are written to this browser's local storage as you type. Treat Export .json as the real save, which Import .json restores anywhere. Export CSV gives you the model for spreadsheet work. Reset asks twice, then erases everything. There is no undo.

The backup contains your unit costs and your pricing intentions. Both are commercially sensitive — keep it off shared drives and out of anything a customer could receive.

Accuracy & disclaimer

The arithmetic is exact; one of its inputs is a guess. The affordable volume loss is a hard fact given your price and unit variable cost. The expected volume loss is a prediction about customer behaviour, and those are wrong routinely and in both directions.

The model also assumes unit variable cost stays constant as volume changes, which fails if losing volume costs you a purchasing tier or under-loads a machine. Use it to find out how much room you have, not to forecast what will happen — and remember that a price rise is a decision about customers and contracts as well as a calculation.