Timer 555 Calculator Pro vs 555 Calc
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Timer 555 Calculator Pro
Calculate parameters for monostable and astable circuits. Find component combinations for desired pulse width or frequency. Share circuit files via iCloud Drive or AirDrop.
- Calculate monostable pulse width
- Calculate astable frequency
- Find component combinations
- Adjust component tolerance
- Unlimited combinations (Pro)
- Share circuit files
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This app is used to calculate monostable and astable circuit. Features * Calculate pulse width of monostable circuit * Calculate frequency of astable circuit * Find out combination of components making a desire pulse width in monostable circuit * Find out combination of components making a desire frequency in astable circuit * Share file to iCloud Drive (For iOS8 or later) * Share file via AirDrop Additional Features in the Professional Edition * Unlimited number of combinations * Allow to change tolerance * No ads
555 Calc
This utility app helps engineers and hobbyists calculate resistor values for circuits using the Timer IC 555. Simply input frequency, duty ratio, and capacitor values to get the required resistor outputs.
- Calculate resistor values
- Input frequency
- Input duty ratio
- Input capacitor value
- Timer IC 555 circuit design
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This App calculates registors value, when designing the circuit using Timer IC 555. How to (1) Input Frequency value. (2) Input Duty Ratio. (3) Input C1 Value. (4) Touch ‘Calculate’ button. (5) Registors value will be displayed. Note. * Set Duty Ratio to 50 ~ 99. * If you set Duty Ratio to 50, R1 value will be set to 0.
Screenshots
Verdict
The clearest difference is review sentiment: Timer 555 Calculator Pro at 100% against 555 Calc's 50%. Timer 555 Calculator Pro also leads on rating (4.7 vs 4.0) and ads (none vs shown). 555 Calc's advantage is price (Free vs $0.99) and iOS requirement (11.0 vs 13.2). On ratings volume, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
555 Calc is free to download; Timer 555 Calculator Pro costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Timer 555 Calculator Pro holds the better App Store score, 4.7 against 4.0. Both are backed by a comparable volume of ratings — 3 and 3 respectively. Written reviews point the same way: 100% of Timer 555 Calculator Pro's written reviews are positive against 50% of 555 Calc's.
Timer 555 Calculator Pro ships an update every 3 months, 555 Calc every 20 months. The most recent releases landed on October 23, 2026 and October 13, 2026 respectively.
| Parameter | Timer 555 Calculator Pro | 555 Calc |
|---|---|---|
| Price | $0.99 | Free — better |
| Rating | 4.7 (3 ratings) — better | 4.0 (3 ratings) |
| Positive reviews | 100.0% of reviews — better | 50.0% of reviews |
| Number of ratings | 3 | 3 |
| Update frequency | Every 3 months — better | Every 20 months |
| Ads | No — better | Yes |
| In-app purchases | No | No |
| Monetization | Paid | Ad-supported — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.2 | 11.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 18 MB |
| Age rating | 4+ | 4+ |
| Developer | Siu Yuen Ho | Jibiki Works |
Customer experience
Timer 555 Calculator Pro
555 Calc
In-app purchases
Timer 555 Calculator Pro
No in-app purchases
555 Calc
No in-app purchases
Questions
Is Timer 555 Calculator Pro free?
Is 555 Calc free?
Which has better reviews, Timer 555 Calculator Pro or 555 Calc?
Do Timer 555 Calculator Pro or 555 Calc have ads?
Which is updated more often, Timer 555 Calculator Pro or 555 Calc?
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