Guides

Can I afford it? Planning a purchase

A question comes up that a budget of buckets and horizons does not answer on its own: is it worth planning to buy the children a piano over the coming months? It is not really a question about the piano. It is a question about whether one more commitment fits alongside the ones you have already made. Duration answers it in place, so the spreadsheet you would otherwise keep beside the app is no longer needed.

The short answer

Tell Duration what you expect to earn in a typical month. It totals what your goals and regular buckets already need each month — your commitments — and shows what is left over: free to commit. A new purchase fits when its monthly cost sits inside that figure. All of it lives on a calm strip at the top of the Overview.

Set your expected income

Open Settings → Income and enter what you earn in a typical month. This is a figure you declare, not one Duration guesses: it is the number every affordability answer is measured against.

It is dated, like a goal. A raise is a new version effective from its date, and the earlier value stays in your history — so a report or a future projection can always read the income you expected at the time. Beside the field, Duration shows the trailing average of income actually received over recent months, as a quiet reality-check. Only the number you declare is used in the arithmetic; the average is there so you can sanity-check it.

What counts as a commitment

Two things make up your monthly commitments, and Duration keeps them visibly apart:

Your goals. Each goal’s required pace — a dated target spread over the months to its deadline, or a recurring target each cycle — counted as a firm monthly figure.
Buckets without a goal. A bucket you feed every month but never set a goal on still spends your income. Duration estimates its monthly cost from your recent allocations into it, and labels that part estimated so it never passes for firm. (Give such a bucket a goal and its estimate becomes a declared figure — Duration will gently suggest this.)

One word of care: commitments is a monthly flow — what leaves each month — and is not the same as allocated, which is a balance already parked in your buckets. They are different quantities and are shown apart.

Free to commit — the answer

Free to commit is your expected income minus your commitments. It is the honest answer to “can I take this on?”. When it is comfortably positive you have room; when it turns red you have committed more than you expect to earn, which is the whole-economy sign that something has to give before you add more.

Try it before you commit: the goal form

The most direct way to plan the piano is to make it a goal. When you set a target and a date in the goal form, Duration reads back what it would cost and whether it fits:

This goal needs about 4 000 a month. You have 6 000 free to commit — fits, with 2 000 to spare.

If it does not fit, the form says so plainly, and the remedy is usually to stretch the deadline or free up room elsewhere.

Play with the figures: Explore

Before anything becomes real, you can explore. The Explore what fits link on the Overview strip opens a scratch panel where you can:

nudge your expected income — what if I earned a little more?;
toggle or edit the estimated buckets, to see the effect of trimming one;
add test rows — a hypothetical commitment, either per month or by a date (the piano before it is ever a goal), and watch free-to-commit respond.

Nothing here is saved. It is a lens over your real numbers, not a second plan — close it and your budget is exactly as it was. When a test row turns out to fit, Make a goal takes you to the ordinary goal-creation flow to record it for real. Duration surfaces the decision; you make it.

The flip side: am I living within my means?

Affordability looks forward. The mirror question — did I over- or underspend? — Duration answers in the same idiom, not with a spending report:

On Reports, a plain line reads the month over month: last month you added 6 000 net; this month so far, 2 000 — money added is living within your means, money drawn down is not.
On a recurring goal, a last-cycle line shows what went in and out — the literal “did this envelope hold”.
A negative bucket is money spent beyond what was allocated to it, and free to commit going negative is the same signal at the scale of your whole economy.

Together, expected income, commitments and free-to-commit give you the picture a budget of pots alone cannot: not just where every unit of money sits, but whether the next thing you want is one you can plan for.

Last reviewed: July 2026.