One calculator, two ways in: what the ladder page solves for in each mode, what its five fields do, and what the allocation table and the two cash-flow charts show.
The bond ladder page is one calculator with two ways in. Both build the same thing — a set of gilts whose redemptions land one a year, each rung sized to a draw — and they differ only in which number you supply and which the page solves for.
The two modes
Two links above the title change mode, and the address remembers which one you are in.
Income target
Income target asks for the annual income you want the ladder to pay and solves for the lump sum that buys it, growing the target by the inflation rate you set so each year's draw keeps its buying power.
Lump sum
Lump sum runs the same ladder the other way round: you give the amount you have to invest and the page reports the income it supports. Nothing else changes between modes — the same rungs, the same gilts, the same sizing — only which end of the calculation is the input.
The five fields
| Field | What it sets |
| Length | How many years the ladder runs for, between three and twenty. One rung per year, so the length is also the number of gilts. |
| Income | The target income the ladder should pay each year, in income target mode, grown by the inflation rate across the ladder. |
| Lump sum | The amount you have to invest, in lump sum mode. |
| Inflation | The expected inflation over the period. Two jobs: it grows the target year on year in income target mode, and it deflates every future payment for the chart in today's money. |
| Tax | Your marginal income tax rate, applied to the rungs' coupons. The one field that changes a net figure rather than the ladder's shape. |
What the page gives back
A readout above the charts carries the answer: the income per year in lump sum mode, the lump sum required in income target mode, the number of gilts, the length, the inflation assumed and the tax rate. Under it, the Allocation card takes each rung in turn.
| Allocation column | What it shows |
| Gilt | The gilt chosen for that year, linking to its own page. |
| Dirty price | The mid dirty price per £100 nominal from the report the card names — clean plus accrued. |
| Allocation | Each rung's share of the lump sum: its dirty value divided by the ladder's combined dirty value. |
| Amount | What this rung costs at its dirty price. |
| Quantity | The £ nominal of the gilt the rung buys. |
A CSV control in the page head exports the ladder on screen, with the mode and inputs the form echoes.
How a rung is sized
A rung is one year's draw funded by one gilt whose redemption lands in that year. The ladder buys each rung at its mid dirty price from the report the card names, so the quantity is what that money actually buys rather than a round £100 of face value. Coupons are not reinvested in the model: a rung's year receives its gilts' coupons and, in the year it matures, that gilt's redemption.
The tax rate is applied to coupon income. Gilts are exempt from capital gains tax, so the redemption is not netted.
The two charts
Cash flows, as paid stacks each year's nominal cash flow: the coupon income from the rungs paying that year, plus, in the year a rung matures, that gilt's redemption.
Cash flows, in today's money takes exactly those flows and deflates each future payment at the inflation rate in the form, treating the ladder's first year as today. Every bar is what that year's payment is worth in today's pounds: a real-terms comparison, where later bars are shorter because their purchasing power has been discounted back, not because the amounts change.
What the page does not do
The ladder page is a calculator. It sizes the rungs and shows what each would cost; it places no order, and it does not record the rungs as trades. To put the gilts you buy into a portfolio, book them on Record a trade — one trade per rung, at the prices on your contract notes — and the portfolio valuations, cash-flow and taxable-income reports pick them up.
It is a projection on stated assumptions, not a plan. The gilts are the ones in issue at the report date, and nothing re-runs as prices move.
The seven terms, and where they are explained
The ladder's vocabulary lives in the glossary with everything else — the last seven entries, because a reader meets them here. Income target and lump sum are the two mode links above the title: one builds a ladder that pays a target income each year, the other a ladder from a starting amount. Length is the number of years the ladder runs for. Income is the target, inflation-adjusted income it should pay each year. Lump sum, the field, is the amount there is to invest today. Inflation is the expected inflation over the period, which grows the target and deflates the real-terms chart. Tax is the marginal income tax rate applied to the rungs' coupons.
Explain mode prints each of those sentences on the page's own label, so the definition appears where the field is. The bond ladder guide covers the idea behind a ladder, and income target versus lump sum works the same inputs through both modes.
The keys behind this page are the glossary's ladder-income-mode, ladder-lump-sum-mode, ladder-length, ladder-income, ladder-lump-sum, ladder-inflation and ladder-tax.