Hundred Summers

Free calculators

Free, no sign-up, no data collected — the calculators run entirely in your browser, powered by the same engine as the full Hundred Summers plan. Education, not advice.

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Would your retirement have survived 1929?
Replay your pot and spending through every real market sequence since 1928 — the Great Crash, the 1966 inflation grind, the lost decade — and watch each history unfold.
Run my plan through history →
Pension drawdown calculator
How long will your pot last, and what could you sustainably spend? A full year-by-year projection with UK income tax and the State Pension — not a rule of thumb.
How long will my pension last →
Inheritance tax calculator
Nil-rate band, residence band with the £2m taper, a late spouse's allowances, the 36% charity rate — and the 2027 rule that brings pensions into the estate.
Estimate your IHT →
Salary sacrifice calculator
Income tax and NI saved on this year's actual bands — including the 60% relief zone between £100k and £125,140, and your employer's NI saving if they pass it on.
What a contribution really costs →
ISA vs pension calculator
The same slice of gross pay, two routes: pension by salary sacrifice, or ISA after tax and NI — compared with the 25% tax-free lump sum and your retirement tax rate.
Which wins for you →
Annuity calculator
What guaranteed lifetime income a pot could buy at indicative market rates — with the real cost of spouse provision, guarantees, inflation-linking and enhanced health rates.
Estimate the income →
State Pension deferral calculator
Deferring adds a permanent ~5.8% a year — in exchange for the income you give up waiting. Find your honest breakeven age on the statutory rules.
Is waiting worth it →
FIRE calculator
Your Lean, Regular and Fat FI numbers, the age each arrives, and your Coast FI figure — in today's money at real growth, on the same definitions as the app's FIRE card.
Find your FI age →
Voluntary NI calculator
Buying a missing National Insurance year costs ~£900 and adds ~£358 a year of State Pension for life. See the honest after-tax breakeven before you check your forecast.
Is topping up worth it →
7-year rule calculator
What a gift really adds to your inheritance tax bill today — with the nil-rate-band ordering rule most explanations miss, and taper relief applied honestly.
Test a gift →
Mortgage overpayment calculator
Interest saved and years cut, month by month — honestly compared against investing the same money instead, including the payment-free years overpaying buys you.
Overpay or invest →
How much do I need to retire?
Not 25× anything: the pot solved by a full year-by-year projection with income tax on withdrawals and the State Pension modelled properly.
Find your number →
Capital gains tax calculator
The £3,000 exemption, then 18% within your remaining basic-rate band and 24% above — gains stack on income, which is what flat-rate estimates miss.
Calculate your CGT →
Pension carry-forward calculator
This year's (possibly tapered) annual allowance plus unused allowance from three prior years — each tapered on its own income, done properly.
What can I contribute →
Take-home pay calculator
Income tax (rUK or Scottish), NI and student loan on your actual salary — plus your true marginal rate, including the hidden 60% zone.
What do I keep →
Bonus tax calculator
No special bonus rate exists — a bonus is income stacked on top of your salary. See what you actually keep, and what sacrificing it would do.
What my bonus keeps →
Dividend tax calculator
The £500 allowance, then the April-2026 10.75%/35.75%/39.35% rates with dividends stacked as the top slice of your income.
Tax on my dividends →
Child benefit calculator
What you claim, what the £60k–£80k High Income Charge claws back, and the pension contribution that would restore the lot.
What we keep →
Student loan calculator
9% above your plan's threshold, through payroll, until it clears or writes off — a tax in all but name, priced on the real plan table.
What I repay →
Pension projection calculator
Your pot at retirement net of charges — with the today's-money figure and what your fees cost against a zero-fee world.
Project my pot →
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Remortgage calculator
Both deals amortised in full: monthly change, interest saved net of fees, fee payback — and the term trap flagged when it bites.
Is switching worth it →
Equity release calculator
The compound roll-up of a lifetime mortgage against your home's value — how much of the house is left, which providers' calculators don't lead with.
What it really costs →
Life insurance calculator
The DIME method with every part visible — Debt + Income + Mortgage + Education, net of cover you already hold.
Size the cover →
Life expectancy calculator
ONS cohort baselines with honest, clamped adjustments — and the plan-to age with the buffer planners add.
My planning horizon →
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When can I retire?
The earliest age your savings fund every retirement year — found by the app's own solver testing each candidate age with the full projection.
Find my earliest age →
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Self-employed tax calculator
Income tax on profits plus Class 4 NI at the real 6%/2% rates — with the Class 2 abolition explained and the NI edge over employment shown.
Profits to take-home →
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Rental income tax calculator
Rental profit stacked on your other income at real bands — including the April-2027 +2pp property surcharge most calculators don't model yet.
Tax on my rent →
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Marriage allowance calculator
Whether transferring £1,260 of allowance actually pays in your household — both sides priced, with four-year backdating worth over £1,000.
Check our claim →
Tax-free lump sum calculator
Your 25% under the £268,275 cap — and the comparison that matters: all up front, or 25% of every withdrawal tax-free instead.
Up front or slice by slice →
Bond gain calculator
Chargeable event gains with HMRC's top-slicing done properly — the years-held slice, the 20% onshore credit, onshore vs offshore.
Tax on my bond →
Lifetime ISA calculator
The 25% bonus projected to 60 — with the withdrawal penalty priced honestly: it takes 6.25% of your own money, not just the bonus.
Bonus and penalty →
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Mortgage repayment calculator
The true monthly payment and the full interest bill over the term, amortised month by month — with the honest interest-only comparison.
What my mortgage costs →
Redundancy pay calculator
The £30,000 tax-free exemption, the excess stacked on your year's salary at real bands — and what paying it into your pension saves instead.
What I keep →
Care costs calculator
In-home, residential and nursing care compounded at care inflation to when you'd actually need it — with the £23,250 means test explained.
Price the care →
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Downsizing calculator
What selling and buying smaller actually frees after moving costs, tax-free — and the lifetime income that capital could buy at your age.
What moving frees up →
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£100k childcare cliff calculator
The 60% tax zone plus the cliff that removes free hours and Tax-Free Childcare at £1 over £100k — and the pension contribution that gets it all back.
Price the cliff →
Student loan overpayment calculator
Whether overpaying buys anything at all — your loan simulated to write-off with real repayment rules, against investing the money instead.
Overpay or not →
Safe withdrawal rate calculator
Not 4% or 3.5% — your personal rate, solved by a full projection with UK tax on withdrawals and the State Pension.
Find my rate →
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ISA bridge calculator
Retiring before pension access: whether your ISA can carry the gap years — tested with pensions locked until they legally unlock.
Test my bridge →
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Debt payoff calculator
Avalanche vs snowball on your actual debts, month by month — time to debt-free and the interest difference priced, so the choice is informed.
Get debt-free →

Prefer reading? Plain-English guides, the tab-by-tab app guide, and every assumption behind the numbers in the published methodology.

Hundred Summers. Education, not regulated financial advice; projections and results are illustrations, not guarantees.
hundredsummers.co.uk·Methodology & assumptions·contact@hundredsummers.co.uk