Free US UK Calculator — Editorial Team
Our editorial team produces and reviews every calculator, formula, and worked example on freeusukcalculator.com. We write for two markets — the United States and the United Kingdom — and update statutory rates annually each April when HMRC and the IRS publish new tax bands.
Our content principles
- Source every number. Every tax band, contribution limit, statutory rate, or health threshold is linked to an authoritative source — gov.uk, IRS publications, NHS, CDC, WHO, NIST, peer-reviewed research.
- Show the formula. Every calculator displays the underlying maths in plain English, with worked examples for both US and UK scenarios.
- Annual rate review. UK statutory rates (SSP, SMP, ISA allowance, IHT thresholds, NI, PAYE) and US tax bands are reviewed each April. Pages display a "Last reviewed" date and are updated within 7 days of any HMRC, DWP, or IRS rate announcement.
- No financial, legal, or medical advice. Calculators provide estimates only. We always recommend consulting a qualified professional (chartered tax adviser, IFA, GP, solicitor) for material decisions.
- YMYL standards apply. Tax, mortgage, retirement, and health calculators meet "Your Money or Your Life" content-quality standards: explicit assumptions, visible formulas, source citations, disclaimer language, and regular review.
How we keep rates current
The UK government publishes its Welfare Benefits Up-rating Order each spring; the IRS publishes annual inflation-adjusted limits each November/December. Our content review cycle:
- November — IRS publishes next-year limits (401(k), IRA, HSA, FSA contribution caps). We update US retirement and tax calculators within 14 days.
- March — UK Spring Statement / Budget published. We pre-draft updates to UK income-tax calculator, NI calculator, ISA limits, IHT thresholds.
- April — New UK tax year begins. SSP, SMP, NI bands, PAYE thresholds, ISA allowance, IHT nil-rate band, pensions allowance changes take effect. All UK calculators are reviewed in the first week of April.
- Year-round — Health calculator thresholds (BMI categories, BMR formulas, body fat ranges) follow WHO, CDC, NHS, and ACE Fitness guidance. Reviewed if any of these bodies update guidance.
Editorial standards for new content
Every new calculator and blog post passes through a five-stage review:
- Source verification. Every numeric claim must trace to a primary source. Tax rates link to gov.uk or irs.gov. Health thresholds link to NHS, CDC, WHO, or peer-reviewed papers. Math formulas link to academic or standards bodies (NIST, ISO).
- Formula validation. Calculator math is tested against the cited source with at least 3 input combinations, including edge cases (zero, negative, very large, boundary).
- US + UK coverage. Calculators that apply to both markets include a unit toggle, country selector, or parallel worked examples. UK-only or US-only calculators are clearly labelled.
- Plain-English review. All content is written at an 8th–10th grade reading level. Jargon is defined or avoided.
- Disclaimer placement. YMYL calculators always include "Estimate only — confirm with [authority] for your specific situation" language.
Subject-matter coverage
Personal finance
UK PAYE + NI, US federal + state income tax, mortgage amortization, pension and 401(k) planning, ISA limits, debt payoff strategies, retirement projections, credit-score mechanics.
Health & fitness
BMI (WHO standard + Asian-adult modified), BMR/TDEE (Mifflin-St Jeor), macro splits, body fat (US Navy method), pregnancy + due-date calculations, hydration, sleep cycles.
Math & science
Percentages, fractions, algebra, geometry, statistics (mean/median/mode/standard deviation), unit conversions, scientific notation.
Everyday utility
Age calculations, date math, tip calculations (US + UK service-charge conventions), fuel cost, time-zone planning, password security.
Contact & corrections
Spotted an outdated rate or a math error? Please tell us via the contact form. We respond within 2 business days and update the affected calculator within 7 days of any confirmed correction.
Disclosure
freeusukcalculator.com is independent. We do not accept payment for editorial placement. The site is monetised via display advertising. No calculator output is influenced by advertiser interests — all calculations follow the cited source formulas exactly.
Profile last reviewed: 18 May 2026.