Prism Calculator
Calculator for everything.
Scientific, currencies, history and seven more calculators. In one app.
On a desktop? Point your camerahere to open the App Store.
Exact math.
Not almost.
Most calculators store decimals in binary and quietly round. Prism computes exactly, so the number you see is the number you get.
0.1 + 0.2 = 0.3
In floating point that famously returns 0.30000000000000004. Prism returns 0.3, because it never converts your decimals to binary.
Full scientific. Free.
Trig, logs, powers, roots, factorial, degrees and radians, memory. No paywall on the maths, ever.
Currencies offline
340 currencies with rates built in and cached. No signal, no problem, and a badge tells you the date the rates are from.
History that works
Every calculation saved, searchable, taggable. Swipe a result back into the keypad instead of retyping it.
Seven more calculators
Tip and split, percentages, discount and tax, loan, dates, unit price, BMI. Built in, open to everyone.
Speaks your language
Twelve languages, right to left included, with the number formatting each one actually expects.
No ads.
No subscriptions.
The calculator is free and shows nothing. One purchase unlocks the rest, once, forever.
Free
- Full scientific mode
- Percentages and history
- All 7 mini calculators
- 12 languages
- No ads, no tracking
Unlock everything
- Once. Never again.
- All 5 themes
- Currency converter
- Every converter category
- History export to CSV
What the others charge.
Prices and ratings read from live App Store listings on 16 July 2026.
| App | Price model | Ads | Rating |
|---|---|---|---|
| Prism Calculatorthis app | Free, $3.99 onceno subscription | None | New |
| Calculator₊ | Subscriptions from $1.49/mo | Banner and full screen | 4.67 |
| Calculator with History + | $9.99 once | None | 4.68 |
| Calculator Air | Subscription only, up to $99.99/yr | None | 4.69 |
| Apple Calculator | Free, built in | None | 3.02 |
Questions.
Does Prism have a subscription?
No. Prism has no subscription and never will, and it shows no ads at all. The core calculator is free: percentages, scientific mode and history. A single $3.99 purchase unlocks the rest, once. There is no renewal and no second charge.
Does the currency converter work without internet?
Yes. Prism ships with exchange rates built in and caches the last rates it downloaded. Offline, the converter keeps working and a badge shows the date the rates are from, so you always know how fresh the number is.
What does the $3.99 purchase unlock?
All 5 themes, the currency converter, every unit converter category, the mini calculators with no use limit, and history export to CSV. One time purchase, restorable on your other devices with the same Apple Account.
Why does 0.1 + 0.2 equal 0.30000000000000004 in most calculators?
Most calculators store numbers as binary floating point, and 0.1 and 0.2 have no exact binary representation, so a tiny rounding error survives into the result. Prism computes with exact rational arithmetic instead, so 0.1 + 0.2 returns exactly 0.3. The long answer is here.