Free financial calculators that show their math
Core-AI publishes browser-based calculators for the personal-finance decisions where the rule is written down somewhere but the arithmetic is hard to do by hand: retirement account limits, equity compensation and the alternative minimum tax, mortgage trade-offs, and health-plan choices. Every calculator states the formula it uses, names the statute or agency guidance it is calibrated to, and walks through a worked example with real numbers.
Who publishes Core-AI
Core-AI is an independent site, built and maintained by its founder, a software architect with twenty-five years of hands-on engineering experience. It is not affiliated with any brokerage, lender, insurer, or tax-preparation firm, and it does not sell financial products or take referral fees from the tools it describes. The site is supported by advertising.
The editorial voice is deliberately neutral. The goal of each page is to tell you what a rule does and what the numbers come out to, not what you should do. None of the people behind Core-AI are licensed tax, legal, or investment advisers, and nothing on the site is individualized advice.
What the site covers
The calculators are organized into four clusters, and each is paired with articles in the Insights section that explain the rule in more depth.
Backdoor Roth pro-rata math, Solo 401(k) versus SEP IRA limits, 401(k) employer match true-ups, HSA growth, 529 state tax benefits, Section 179 vehicle deductions, tax-loss harvesting, and state tax relocation.
Refinance and discount-point breakevens, recast versus refinance, extra principal versus investing, amortization, affordability, BRRRR underwriting, and rent increase versus moving cost.
ISO versus NSO exercises and Form 6251 AMT, RSU withholding shortfalls and underpayment penalties, total-compensation offer comparison, W-2 versus 1099 versus corp-to-corp, and freelance rate pricing.
High-deductible plan with HSA versus PPO at open enrollment, the HSA triple tax advantage, and the long-run reimbursement strategy sometimes called the stealth IRA.
The site is US-focused, with one Australian Age Pension calculator and two UK pension articles that the same audience asked for. Calculators that are still being built are kept out of search results until they meet the standard below.
How each calculator is built and checked
- Primary sources only. Thresholds, limits, and rates come from the IRS, the Treasury, the Federal Reserve, the Consumer Financial Protection Bureau, or the equivalent agency for the jurisdiction, and the page links to that source. If a figure cannot be traced to a source, it is not published.
- The worked example is computed by the calculator's own code. The numbers you read in the prose are the numbers the page produces for those inputs, so the explanation and the tool cannot drift apart.
- Every page states the tax year it reflects and the date it was last reviewed. Annual limits are updated when the agency publishes them.
- Drafting is AI-assisted; publication is not. Explanatory text is drafted with AI assistance, then reviewed against the calculator's code and the cited sources, and run through an automated check for broken links, mismatched schema, and unsupported claims before it goes live.
- Corrections are welcome. If a figure is wrong or a rule has changed, email support@core-ai.app with the page URL. Fixes are noted in the page's review date.
How your inputs are handled
The calculators run as JavaScript in your browser. The figures you type into a calculator are used on your device to produce the result and are not sent to Core-AI's servers as part of the calculation.
Some pages offer an optional AI explanation panel. When it can, that panel runs a model locally in your browser. When your device cannot, it asks for your confirmation before sending your inputs to Core-AI's AI endpoint to generate the explanation. Nothing is sent unless you click the button and confirm. Advertising and analytics on the site use cookies as described in the privacy policy.
Contact
Publisher: Core-AI (core-ai.app), United States
Email: support@core-ai.app
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