Four steps
Enter your plan
Add your income, spending, pensions, savings and the big dates ahead. Rough numbers are fine to start.
See your Roadmap
See your money year by year to the end of your plan, with UK tax worked in and figures in today’s money by default.
Explore changes
Try a different retirement age, spending level or big purchase and see what it does to your plan. Foresight can explain what changes.
ProSaving scenarios and the full before-and-after comparison with your plan are part of Pro.
Keep it up to date
Check in your balances now and then and the Roadmap recalculates from them. Your history shows what has moved.
ProPro adds a benchmark, so you can see whether you’re ahead or behind your plan.
How our numbers work
Your Roadmap, scenarios and history all use the same calculation engine. These sections explain how it works and what it leaves out.
One deterministic engine
Every projection in Wealthcast comes from a single deterministic calculation engine. The same inputs always produce the same outputs — there is no hidden randomness and no model that changes its answer between visits. When you compare scenarios, both sides are computed by the same rules, so differences come from your choices, not from noise.
Today's money by default
Projections start in today’s money: what future amounts would be worth today, after inflation. A number thirty years out is directly comparable with your budget now, so growth you see is growth in purchasing power — not inflation dressed up as progress. Roadmap charts can also show future pounds; tables, CSV exports and Foresight stay in today’s money.
UK tax rules built in
Income tax, National Insurance, and the supported UK allowances and wrappers are part of the calculation, not an afterthought. Tax-year figures are maintained centrally in the engine and reviewed when rules change. Your plan shows which tax year and regional income-tax rules it is using.
Plan assumptions and model parameters
The app shows your main plan assumptions. You can change plan settings, while Pro adds custom growth, inflation and salary growth. Some model parameters, including how market returns vary in stress tests, are fixed rather than editable plan settings.
Growth rates are after charges. The defaults are estimates of long-term returns above inflation once typical fund and platform costs are paid, so there is no separate charges box. On Pro, you can adjust the rate if your costs are unusually high or low.
Where we show a saving rate, it is saving divided by gross recurring income — including pension contributions — not take-home pay.
Example: testing an earlier retirement
If you test retiring earlier, Wealthcast keeps the same plan and current balances, changes the retirement timing, then calculates each year again. It applies the supported income, spending, tax and account rules in sequence. The comparison shows what changed and when; it does not decide whether retiring earlier is right for you.
The Roadmap and stress testing
The Roadmap is a deterministic projection: one path, computed from your plan under its current assumptions. Every year follows from the last — income, spending, tax and growth applied in sequence — so you can trace any figure back to what caused it. It shows the logic of your plan, not a forecast of what markets will do.
A stress test varies market returns by design. It re-runs the same plan across up to 5,000 simulated sequences of market returns, stopping early when the result is steady. It can also check a one-year market drop at any age. The Roadmap holds growth steady so you can read your plan clearly. A stress test is where market ups and downs come in. It is a separate second layer, on top of numbers you have already checked.
A stress test reports the share of those runs in which planned spending is covered along the way and the plan finishes on target — for example, 4,300 of 5,000 simulations held up. Its main chart shows that share at each age. Once a path fails, it stays failed. The Asset balances view instead shows how much money every path holds at each age, including paths that fell short earlier. Read the headline as a robustness check on your assumptions: how your plan copes when the same returns arrive in a different order. It is not the probability of what will happen to you, and it does not tell you whether a plan is right for you.
The same page also runs a Market downturn test. Instead of many random sequences, it applies a single run of weak years to your pensions, ISAs and investment accounts. The pattern is one Wealthcast designs and keeps in a versioned table. The test then sets the result beside your usual growth. For your own plan it shows the adjustment applied to each year, when usual growth resumes, and which assets it touches, so you can read the workings. It is neither a record of a past market fall nor a forecast of what markets will do. The growth it applies is after inflation, on the same after-charges basis as your plan’s usual assumptions.
We keep the two apart on purpose. A single blended chart would hide both: you could no longer trace a year in the Roadmap, nor inspect how a stress test was built. Legible, auditable numbers you can interrogate come first, and market volatility is handled as a layer you add on top. Stress testing is part of Pro.
Scope and important limitations
- Wealthcast is an illustrative cashflow modelling tool, not regulated financial advice. We don't recommend products or providers, and we don't rank your options.
- The result depends on the information and assumptions in your plan. Wealthcast does not verify your balances, provider terms or personal tax records.
- The engine models the UK rules it supports, with some documented simplifications. It does not cover every exception in tax law, every pension scheme rule or every future policy change.
- Deterministic means the same inputs produce the same result. It does not mean the future is certain. Markets, inflation, tax rules and your circumstances can change.
- Financial figures come from the calculation engine. Foresight uses those results when explaining your plan and drafting scenarios, but a generated explanation can still be wrong. Nothing changes without your confirmation.
Wealthcast is an illustrative cashflow modelling tool, not regulated financial advice. Projections use simplified assumptions and default to today's money. Your actual outcomes will vary. Read the full disclaimer.