James Blanckenberg

Founder & Editor, FinCalcHub.

Background

I'm James — the person behind FinCalcHub. I started the site in 2024 after spending years running the same compound-interest, retirement, and take-home-pay numbers on a notepad and finding no single tool that handled all three regions I care about (the USA, the UK, and South Africa) without paywalls, sign-up forms, or pre-calculation ads.

I was born and educated in South Africa, moved to the United Kingdom in my twenties, and have spent the better part of two decades managing my own money across the three tax regimes that most of my family, friends, and former colleagues now live under. That cross-border life is what most of the content here is about: the maths is universal, but the wrapper around it — the tax tables, the contribution caps, the account types, the rebates — changes every time you cross a border. Sites that handle one region well usually pretend the other two don't exist; sites that try to handle all three usually water the math down to the point of uselessness. FinCalcHub exists in the gap between those two failure modes.

I'm a sole operator, not a venture-backed startup. I write the calculators, the explanations, and the underlying formulas; I also run a sister site for small-business owners called BusCalcTools. My professional background is in product and technology, not regulated financial advice — and that's deliberate. The site sticks to the lane that doesn't need an advisory authorisation: running the actual published math, citing the primary source for every figure, and pointing readers at a qualified professional whenever the question moves from "what does the formula say" to "what should I do".

The reason I write about personal finance specifically — rather than business finance, which is what BusCalcTools is for — comes down to lived experience. Cross-border income, pension consolidation, contribution-cap stacking across the UK ISA and the SA TFSA, the mechanics of a UK SIPP holding USD-denominated assets, the SA Two-Pot system rolling out alongside an unchanged UK auto-enrolment scheme: these are problems I've actually had to solve, with my own money, against the actual published rules. The articles and calculators on FinCalcHub are the tool I wanted when I was the user.

Areas of focus

The site has four topic clusters I write about regularly. Each cluster has a calculator (or several) at its centre and a set of explanatory articles around it.

• Compound interest and investment projections. The math of FV = PV(1 + r/n)^n·t, what to use for r in nominal vs real terms, how to interpret a "7% expected return", sequence-of-returns risk, the difference between a Monte Carlo simulation and a deterministic projection.
• Tax across three regions. UK income tax + National Insurance + dividend tax + the personal-allowance taper above £100,000; US federal brackets + FICA + state-level effects at a high level; South African PAYE + primary/secondary/tertiary rebates + medical credits + the retirement-fund deduction cap.
• Retirement. How much you actually need (with the 4% rule, the 25× rule, and where they break); the mechanics of a 401(k), Roth IRA, SIPP, ISA, TFSA, and SA RA; the SA Two-Pot system; how the UK State Pension's qualifying years interact with private provision; FIRE numbers under each region's tax regime.
• Mortgage and home-purchase math. The standard amortising annuity formula; how UK stamp duty, SA transfer duty, and US closing costs change the all-in cost; rent-vs-buy break-even; refinance and re-mortgage math; how income multiples and DTI ratios are applied by lenders in each region.

Sources used routinely

The articles I write reference the same primary sources, week in and week out. The full source hierarchy is on the editorial policy page; the headline list of the publications I open most often:

• United Kingdom: HMRC (tax tables, NI thresholds, ISA limits, pension allowances, dividend tax), GOV.UK (state pension, stamp duty land tax, marriage allowance), the Bank of England (Bank Rate, inflation reports, monetary policy summaries), the Office for National Statistics (CPI, RPI, regional wage and house-price data).
• United States: the IRS (federal tax brackets, retirement contribution limits, standard deduction, RMD tables), the Social Security Administration (FICA, OASDI wage base, benefit formulas), the Bureau of Labor Statistics (CPI-U, employment statistics, wage data), the Federal Reserve and FRED for historical series.
• South Africa: SARS (PAYE tables, primary/secondary/tertiary rebates, retirement-fund deduction limits, medical tax credits, capital gains tax inclusion rate), the South African Reserve Bank (repo rate, MPC statements, inflation reports), Statistics South Africa (CPI, labour-force survey data), GEPF and the major retirement-fund administrators for fund-specific rules.
• Markets and long-run data: S&P, MSCI, and FTSE Russell for index data; Robert Shiller's published series for long-run US equity returns; Aswath Damodaran's annually-updated datasets for risk premia and historical returns; the Halifax and Nationwide house-price indices for UK property; FNB and Lightstone for SA property.

Editorial responsibilities on the site

As the sole operator, I sign off on every calculator and every article that goes live. The specific responsibilities that come with that:

• Calculator logic. I write the formula for every calculator on the site, by hand, in JavaScript. I test each formula against a worked example calculated independently (usually in a spreadsheet against a regulator's published table) before the calculator goes live.
• Source verification. Every quantitative claim in an article — every tax band, every contribution cap, every historical return — is checked against the primary source before publication. I do not cite a figure unless I've opened the source and verified the figure myself.
• Review cycles. I run the annual deep review for each jurisdiction (April for the UK post-tax-year-end, February/March for SA after the National Budget, January for US after the IRS publishes new limits). The quarterly review of top-traffic pages is also mine. Reader-reported corrections are acknowledged within 24 hours and published within 48 where they're factual.
• Schema and metadata. The structured data (JSON-LD, OpenGraph, breadcrumbs) on every page is written by hand. dateModified is bumped whenever a page is reviewed.
• Corrections. Every correction email comes to me personally. I reply to every one.

What I do not do

FinCalcHub is deliberately narrow about what it is. The list of things I, as the author, do not do:

• Investment advice. I will not tell you which fund to buy, what your asset allocation should be, or whether to buy or sell anything. Where a calculator needs an expected return as an input, the page explains the historical evidence and leaves the choice of input to you.
• Tax advice. I am not a registered tax practitioner in any jurisdiction. I explain how the tax rules work in general terms; I do not advise on a specific tax position, structure a tax return, or sign off on filings.
• Regulated financial planning. I am not authorised by the Financial Conduct Authority (UK), registered with the Financial Sector Conduct Authority (South Africa), or registered as an investment adviser with the SEC or any state authority (USA). I will not produce a financial plan or advice document for any reader.
• Product recommendations. I will not recommend a specific bank, broker, lender, insurer, or investment platform. The site does not run "best of" lists and does not take affiliate fees from product issuers. Where an article needs to mention a product type — an ISA, a SIPP, a 401(k) — it describes the wrapper, not the provider.
• Anonymous content. Every calculator and article on FinCalcHub carries my byline. There are no ghost-written articles, no unsigned posts, and no AI-generated content published as my own work.

For questions that move beyond what the site is built to do — a specific tax position, an estate plan, a recommendation between two pension wrappers — please consult a qualified professional in your jurisdiction. The "About" and "Editorial policy" pages explain who to look for.

Where to find me elsewhere

The two places I post under my own name, in personal-finance and calculator-building contexts:

• LinkedIn — professional background, work history, and the occasional post about something I've learned building the site.
• BusCalcTools — the sister site for small-business owners, with the same editorial standards applied to profit margin, pricing, and cash-flow calculations. If you run a business as well as a household, both sites are worth bookmarking.

Contact and corrections

Spotted a calculation that doesn't match your situation, a tax band that's out of date, or a typo? Email [email protected]. The corrections workflow, end to end: every email gets a personal reply within 24 hours confirming receipt and whether I agree the page needs changing; factual corrections are verified against the primary source and published within 48 hours; substantive rewrites take longer and you'll be told that up front; where a correction materially changes an answer a reader might have acted on, the change is noted visibly on the page rather than silently edited. The full corrections process is on the editorial policy page.

— James