ReckonBoxFree calculator widgets for your website
Every calculator on ReckonBox embeds on your own site with a single line of HTML. It is free, there is no signup, and the widget shows the same formula-backed result your readers would get here, kept current by us. Pick a calculator, copy the iframe, and paste it where you want it to appear.
How to embed a calculator
- Open the calculator you want, from the set below or anywhere on the site.
- Scroll to the "Embed this calculator" box and copy the iframe code.
- Paste it into your page, post, or CMS. There is no script to add and nothing to maintain.
Popular calculators to embed
Mortgage Calculator
Your full monthly payment with taxes, insurance, HOA and PMI, plus the two dates the mortgage insurance can actually come off.
Compound Interest Calculator
Grow a balance with regular contributions and see the equation behind it, including the contributions term that ranked calculators run but never print.
BMI Calculator
Find your body mass index, weight category, and healthy weight range for your height, using either the WHO or the Asian BMI cutoffs.
Fuel Cost Calculator
Work out the fuel cost of a trip in miles or kilometres, from your MPG or km per litre and the gas or petrol price, with the cost per mile or per km.
Salary Calculator
Turn a gross salary into net pay per paycheck for 2026, with Social Security, Medicare, federal tax, and real 50-state income tax as separate lines.
Home Loan EMI Calculator
Work out your home loan EMI and total interest, the EMI for every loan size at your rate, and the tax you save under Section 24(b).
Debt Payoff Calculator
Compare the snowball and avalanche methods across all your debts, with both numbers that matter: the interest avalanche saves and when snowball clears one.
Calorie Calculator
Work out how many calories to eat a day to lose, maintain, or gain weight, with your choice of the Mifflin or Harris-Benedict formula.
Sales Tax Calculator
Add sales tax to a price or work the pre-tax price back out of a total, using a dated state-average rate or your own, with the state and local split shown.
AI Value Calculator
See the return on a business AI investment: net value, ROI, payback and NPV, weighing your upfront and ongoing cost against the savings and revenue it drives.
Age Calculator
Find your exact age in years, months and days from a date of birth, with totals in weeks and days, the weekday you were born, and your next birthday.
Tip Calculator
Work out the gratuity and split it across the table, with the pre-tax-versus-total choice made explicit instead of assumed.
Frequently asked questions
Is it really free?
Yes. Every calculator embeds free, on any site, with no account and no usage limit.
Do I have to credit ReckonBox?
The widget carries a small "on ReckonBox" link back to the full calculator. Keep it in place; that link is the only thing we ask for in return.
Will the embedded calculator stay up to date?
Yes. The widget loads live from ReckonBox, so rate changes and fixes reach your readers without you touching the embed.
Will it slow my page down?
The embed is a single lazy-loaded iframe with no script, so it loads after your own content and does not block the page.
Which calculators can I embed?
All of them. Every tool on the site has an embed version, and the ones above are just a popular place to start.