How We Build and Review ToolPond Tools
Who makes the tools, which formulas they use, and how mistakes are corrected.
ToolPond is created, operated and maintained by Shahid Abbas, an individual web developer based in Pakistan. There is no company behind the site at this time. Every calculator and guide is written by the operator. No medical, financial or other expert reviews the content at present, and the site does not claim otherwise.
How a tool is built
- Choose a published method. We use a standard formula or rule where one exists, and name it on the page.
- Write it in the browser. Tools are plain HTML, CSS and JavaScript. Your inputs stay on your device.
- Check against known answers. We test with worked examples whose answers can be calculated independently, and with edge cases such as zero, very large or empty inputs.
- Show the working. Where it helps, the page displays the formula and the steps, so you can verify a result yourself.
- State the limits. Pages explain assumptions and when a result may not apply.
Formulas and sources
| Tool | Method used | Reference |
|---|---|---|
| Pregnancy due date | Naegele's rule: first day of last period + 280 days, adjusted for cycle length. IVF, conception and ultrasound dating use fixed offsets. | ACOG Committee Opinions 700 (estimating the due date) and 579 (term definitions) |
| BMI | Weight in kg divided by height in metres squared. Adult categories from 18.5, 25 and 30. | World Health Organization; CDC adult BMI categories |
| Calories and macros | Mifflin-St Jeor equation times an activity factor. Katch-McArdle when body fat is entered. | Mifflin et al., Am J Clin Nutr, 1990; Katch and McArdle |
| Body fat | U.S. Navy circumference method and a BMI-based estimate. Category ranges follow ACE. | U.S. Navy method; American Council on Exercise |
| Percentage tools | Standard percentage formulas, shown step by step. | Arithmetic definitions |
| Mortgage, loan, auto loan and payment tools | Standard fixed-rate amortization: payment = P × r ÷ (1 − (1 + r)−n). | Standard financial mathematics |
| Compound interest and retirement | Compound growth with regular contributions at an assumed constant return. The 4% rule is shown as a rule of thumb only. | Standard financial mathematics |
| Currency converter | Fixed reference rates for a set of major currencies, not live market rates. | Approximate values |
Where several formulas are in common use, the page says which one it uses.
Keeping content up to date
- Pages show a "last updated" date when their content changes in a meaningful way.
- Values that change over time, such as rates and tax brackets, are labelled as approximate and should be checked against an official source before you rely on them.
- When a reader reports an error we check it, fix it, and update the date.
Games
Games are built in-house in JavaScript. Each game has a guide page that explains the rules, controls and tips. Games are for entertainment only.
Report an error
If a result looks wrong, email shahid_abbas_haider@hotmail.com or use the contact page. Please include the page address and the numbers you entered. We aim to reply within two business days.
See also: Disclaimer · Terms of Use · About ToolPond
Last updated: October 7, 2026