Horizon-based budgeting
Know what your money is for — and where it ought to sit.
Duration is a budgeting app for money that doesn't all sit in one account. Every amount gets a purpose and a time horizon, and the horizon decides where it is held — as cash, in a low-risk fund, in shares. Duration keeps the plan and the accounts in step.
| Horizon | Held in | Allocated | Funded | Drift |
|---|---|---|---|---|
| Out-of-pocket | Debit account | 10,000 | 12,000 | +2,000 |
| Short-term | Low-risk fund | 40,000 | 38,000 | −2,000 |
| Medium-term | Mixed fund | 80,000 | 80,000 | — |
| Long-term | Equities | 200,000 | 200,000 | — |
A worked moment: 2,000 assigned to short-term on payday is still in the debit account. Short-term reads 2,000 under and out-of-pocket 2,000 over — one transfer closes both.
If you budget with envelopes and keep your savings invested, you already know the gap.
Zero-based tools assume budgeted money waits as cash: anything invested falls out of the budget and into "tracking accounts". So you keep the reconciliation going yourself — in your head, on your investment platform, or in a spreadsheet — matching what each amount is for against where it actually sits. Duration was built for exactly that work.
What it does
Drift
Allocated is what you have promised; funded is what the accounts hold. Duration shows the gap at every horizon — and the one transfer that closes it.
Goals engine
One-off by a date, or recurring on an anchor you choose. Save a sum, or keep a balance topped up. Two choices cover every target.
Traceability
Every balance is computed from the journal, never stored. Corrections keep their dates. Export everything, any time.
Two-axis model
Purpose says what the money is for. Horizon says when you will need it — and therefore where it should sit.
Import & reconcile
Bring in bank CSVs, sort transactions when you have time, and check each statement ties out — invested accounts included.
Legible, not optimising
Duration records your decisions and shows their consequences. It holds no opinion about markets and moves nothing for you.
Spotlight · goals
Goals that match how you actually save.
A goal is two decisions. When: a date, or a recurring anchor — the 25th of every month, a weekday, a yearly date. What: contribute a sum, or hold a balance. Four combinations, no tangle of target types.
And spending from a bucket never erases what you saved toward it — a drawdown is the goal doing its job, not backsliding.
Spotlight · traceability
Every number traces back.
Duration stores no balances. Every figure is derived from a journal of postings, as of any date you ask — so the numbers cannot quietly disagree with the record. Corrections keep the original date, deletions are recoverable, and the whole ledger is searchable and yours to export.
Stated plainly
- No optimiser
Duration records your decisions and shows you their consequences. It will not move your money for you, or tell you that now is the moment to act.
- Friction on purpose
Deciding where money goes is the one part worth doing by hand — it is where the judgement lives. The tool is here to inform that, not to automate it away.
- A desk, not a phone
Reviewing, reconciling and allocating are sit-down work, not taps on the move. Duration is a web app, made for the desk.
Register interest
Being built now, in earnest.
Duration is in active development, and will open to others once it does what it promises — no sooner. If the picture above is one you recognise, leave your address and you will hear when there is something worth trying.
No newsletter and no marketing lists — just the occasional note when there is real news about Duration. Your address is used for nothing else, and you can ask to be removed at any time.