What is CalcFit? A mental math app built on short timed drills

CalcFit, full name CalcFit: Mental Math, is a mental math app for Android that trains your arithmetic with short timed drills. Each set runs against a timer, the questions get harder as you improve, and mixed rounds lean toward the skills you find hardest. I built it. It works offline with no account.

It is a practice tool, not a calculator. The point is to get faster and more accurate in your own head.

Key points

• Full name: CalcFit: Mental Math.
• What it does: timed speed drills with a separate difficulty level for every skill.
• Six drill types: times tables up to 20, squares and cubes, percentages, fractions, estimation and a mixed speed round.
• Where: Google Play, com.etesttech.calcfit. Not on the App Store yet.
• Who for: teens and adults aged 16 and over, including people preparing for aptitude tests and interviews.

What does CalcFit train?

Drill	What you practise
Times tables	Multiplication up to 20 × 20
Squares and cubes	Recall of squares and cubes
Percentages	Percent of a number, increases and decreases, "what percent is this?"
Fractions	Fractions of a number and fractions as percentages
Estimation	Getting close, fast; answers inside a tolerance count
Mixed speed round	All the skills you have opened, in one timed set

Percentages, fractions and estimation are part of CalcFit Plus. Tables, squares and cubes are there from the start.

How does the difficulty adapt?

CalcFit keeps a separate level for each skill. Answer quickly and correctly and that skill steps up; slip and it eases off. Mixed rounds pull more questions from your weakest skills, and after each set you can jump straight into the skill that needs work.

That matters because most people are not equally slow at everything. You might be quick on tables and slow on percentages. A single difficulty slider hides that; a level per skill shows it.

What do you see after a set?

• Accuracy for the set
• Average speed per question
• Your longest streak of correct answers
• The skills to practise next
• The questions you missed, so you can review them

Who is CalcFit for?

• Aptitude and numerical reasoning tests. Speed on percentages and estimation is what those tests reward.
• Interviews and work. Quick sums in meetings, shops and spreadsheets.
• Keeping sharp. A few minutes a day, with a streak counter and an optional daily reminder at a time you choose.

CalcFit is independent. It is not linked to any exam board or test provider.

Who makes CalcFit?

I do. I am John Osakwe, and I have built apps and websites under Etest Tech Hub since 2015. CalcFit is listed on Google Play under E-TEST APPS. More details are on the CalcFit page.

What CalcFit does not do

• It does not need an account or sign up.
• It does not send your practice history anywhere; it stays on your phone.
• It is not a calculator, and it is not on the App Store yet.

Frequently asked questions

Is CalcFit a calculator?

No. CalcFit is a trainer. It asks you questions against a clock so you get faster at doing the sums yourself.

Does CalcFit work offline?

Yes. It works with no internet connection, and your progress is saved on the phone.

Is CalcFit good for aptitude test practice?

It drills the arithmetic those tests lean on: percentages, fractions, estimation and quick multiplication, all against a timer. It does not copy any test provider's questions and is not linked to one.

Is CalcFit on iPhone?

Not yet. CalcFit is on Google Play for Android. I will add the App Store link here when an iPhone version is live.

What age is CalcFit for?

Teens and adults, aged 16 and over.

How I wrote this

On 3 November 2026 I read the CalcFit Google Play listing and checked search volumes in Google Keyword Planner and Google Trends for the United States. The app details come from the app I built.

By John Osakwe, founder of Etest Tech Hub. I have built apps and websites since 2015, including Etest CBT, FizzFree and Pawlarm.