A free Omni Calculator alternative that runs in your browser

Try it now: Percentage Calculator

Calculate percentages, percentage change, increase, decrease, and ratios instantly.

This is the real tool, not a demo. Open Percentage Calculator on its own page.

AltFTool vs Omni Calculator

Omni Calculator is the strongest editorial operation in this list: 3,899 calculators, each with a named author and a named subject-matter reviewer, plus regular audits of health and finance content. On calculator quality and coverage they are ahead of us and we are not going to pretend otherwise. The reason to have AltFTool bookmarked as well is that a calculation is rarely the whole job. Omni is calculators only — no files, no images, no PDFs, no developer utilities — so the step before and after happens somewhere else.

Omni Calculator's free tier, in their own words

• No premium tier, no subscription and no paywall — the homepage advertises '3899 free calculators' and their About page says being 'free of charge' was a foundational decision
• Embedding is free today but explicitly not guaranteed: 'Omni Calculator reserves the right to introduce charges for embedding or using calculators in the future.'
• Advertising cookies are placed by their advertising partners and are used to build a profile of your interests and show you relevant adverts on other sites
• Analytics cookie retention runs long: the storage period 'depending on the country and the purpose of the cookie, may be up to 24 months'
• Calculators only — no file handling, no PDF/image/document tools, no developer utilities
• Coverage is uneven across their 14 categories: Math 683, Finance 610 and Physics 542 are deep, but Ecology has 34 and Food has 70

Checked on 2026-07-25 against www.omnicalculator.com/, www.omnicalculator.com/about-us, www.omnicalculator.com/privacy-policy, www.omnicalculator.com/editorial-policies, www.omnicalculator.com/discover. Vendors change their plans — if something here is out of date, trust Omni Calculator's own page over ours.

What Omni Calculator does better

Plenty of people should keep paying for Omni Calculator, and these are the reasons why.

• Their editorial process is published and genuinely rigorous: build and test the algorithm, write the article with equations and sources, have it 'Reviewed by ... another person specialized in the topic' for fact-checking, then professional proofreading — and the author and reviewer are named under each calculator's title.
• Unmatched long-tail coverage — 3,899 calculators spanning topics most sites ignore entirely, including ecology, food, sports, construction, biology and chemistry, so obscure queries actually get a purpose-built tool.
• A clear, unambiguous privacy commitment on calculator inputs: 'We neither store nor sell the data you enter into our calculators.'
• Content is maintained rather than left to rot — they run 'regular audits for the content that may change with time, especially in health and finance', and the visible 'Last updated' date reflects changes including 'modifications in calculation algorithms'.

And what AltFTool does not do

• Their editorial process — named author, named subject-matter reviewer, professional proofreading, scheduled audits — is more rigorous than ours.
• 3,899 calculators with deep long-tail coverage in physics, chemistry, biology and construction. We do not match that breadth in the sciences.
• Omni publishes a 'Last updated' date that reflects algorithm changes; our calculator pages do not surface that yet.

Visit Omni Calculator

Where each Omni Calculator job goes here

Left: what you clicked on Omni Calculator. Right: the tool that does the same job here.

• Percentage CalculatorPercentage Calculator
• BMI CalculatorBMI Calculator
• Unit conversion calculatorsUnit Converter
• Age CalculatorAge Calculator
• Days Between DatesDays Between Dates Calculator
• Percentage ChangePercentage Change Calculator

The tools that cover Omni Calculator work

• Percentage CalculatorCalculate percentages, percentage change, increase, decrease, and ratios instantly.Open
• BMI CalculatorCalculate your Body Mass IndexOpen
• Unit ConverterConvert units instantly across multiple categories with accuracy.Open
• Age CalculatorCalculates age based on birthdateOpen
• Days Between Dates CalculatorCount the days, weeks and months between any two dates.Open
• Currency ConverterConvert global currencies instantly using accurate real-time rates.Open
• Percentage Change CalculatorFind the percentage increase or decrease between two numbers.Open
• Basic CalculatorA premium glassmorphic calculator. Supports basic arithmetic operators (+, -, *, /), memory storage, signs, and calculation history.Open

Questions people actually ask

Does Omni Calculator cost anything?

No. It is entirely free with no paywall. They do note they reserve the right to charge for embedding calculators in future, which matters if you are planning to embed one on your own site.

Which has more calculators?

Omni, in the sciences — 3,899 across 14 categories, with real depth in physics, chemistry and construction. Our advantage is regional finance and education calculators, plus everything that is not a calculator at all.

Are my inputs private on either site?

Omni states they neither store nor sell what you enter, and our calculators run entirely in your browser. Both sites do carry advertising, and Omni's policy notes advertising partners set profiling cookies.