Frequently Asked Questions

You only need an espresso machine and a digital scale (preferably accurate to 0.1g). Coffee Rings works with any equipment:

• Entry-level machines: Delonghi, Krups, etc.
• Prosumer machines: Rancilio Silvia, Gaggia Classic
• High-end equipment: La Marzocco, Rocket, etc.

Optional: Timer (often built into scales) and thermometer for more precise measurements.

You don't have to turn every shot into a scientific experiment, but a few basic values are necessary if you want to improve systematically.

Minimum for meaningful recommendations:

• Dose (coffee amount in grams)
• Yield (espresso amount in grams)
• Approximate extraction time
• Simple taste evaluation

Coffee Rings deliberately focuses on a few important values to keep the effort manageable.

Simply start a new analysis in the app:

1. Choose your beans and drink (espresso, cappuccino, etc.)
2. Follow the steps to enter your parameters
3. Rate the taste in 5 simple categories
4. Get up to 3 concrete improvement suggestions

Tip: Start with a shot you know well - this way you'll directly see which next steps Coffee Rings suggests.

Coffee Rings works with all beans, but you'll get much better results with high-quality beans:

Optimal:

• Freshly ground: Grind beans just before brewing
• Local roaster: Freshly roasted, degassed beans (2-4 weeks old)
• Known origin: Single origin or blends with clear flavor profiles
• Visible roast date: Avoid beans without roast dates

Avoid:

• Pre-ground coffee (loses aroma quickly)
• Supermarket beans without roast dates (often stored for months)
• Very dark roasts (less room for adjustments)

Rule of thumb: If coffee doesn't taste good after 10 attempts, it's probably the beans, not your technique.

Absolutely! Coffee Rings works even with limited equipment.

Common limitations:

• No temperature control: Just work with available temperature
• No grinder: Pre-ground coffee is a compromise, but possible
• Fixed grind setting: Focus on dose and time adjustments
• Unknown temperature: Estimate based on machine type (usually 88-93°C)

How to proceed:

1. Enter the parameters you can control
2. Mark fixed parameters as "unchangeable" in notes
3. Focus on recommendations you can implement
4. It might take a few more attempts, but improvements are possible

Limitations: Very light or very dark roasts without temperature control can be challenging. But even then, it's worth trying - surprising improvements are often possible!

No! 25 seconds is a rule of thumb, not a law. Good espresso exists outside this window too.

Coffee Rings considers your entire context:

• Roast level of beans (light = often longer, dark = often shorter)
• Desired drink (espresso vs. americano)
• Your taste goal (more body, less acidity, etc.)

The app suggests optimal timing based on all these factors - which could well be 20 or 30 seconds.

Espresso consists largely of crema right after extraction. Several factors affect volume:

• CO₂ content in the puck (depends on roast date)
• Bean freshness
• Extraction speed
• Crema formation

The problem: 30ml of espresso can weigh between 25g and 35g depending on crema. Weight is reliable, milliliters are not. That's why Coffee Rings exclusively uses grams for yield.

Recommendation: A scale with 0.1g accuracy is ideal, but 1g accuracy also works.

Why precision matters:

• Dosing: 1g difference at 18g = 5.5% strength change
• Ratio calculation: Accurate ratios are crucial for recommendations
• Reproducibility: Consistent measurements for comparable results

Practical tips:

• Budget option: Simple kitchen scales from $20 are sufficient to start
• Timer function: If possible, choose scale with integrated timer
• Placement: Scale should fit under cup for direct weighing

No, only time under full pressure counts. Pre-infusion is recorded separately.

What is pre-infusion? Pre-infusion wets the puck gently before full pressure.

Why: It can reduce channeling and smooth out extraction, especially with lighter tamp or coarser grinds.

How (E61 example): Slightly open the lever/valve until you hear water entering the portafilter, but not enough to start the pump. Hold for a few seconds, then engage full pressure for the shot.

Time measurement:

• Pre-infusion: E.g., 3-5 seconds (enter separately)
• Shot time: Only time under full pressure (e.g., 27 seconds)
• Total: App considers both values for recommendations

A recipe is finished when you're satisfied with the taste - not when all parameters are theoretically ideal.

Positive signs:

• Balanced taste: Acidity, sweetness, and bitterness harmonize
• Repeatability: Last 2-3 shots tasted similarly good
• Your preference: You look forward to the next cup
• Stable parameters: Small changes worsen the taste

When to stop:

• After 8-10 attempts without clear improvement
• When you're satisfied - even if theoretically "optimizable"
• With new beans: Use as baseline and adjust as needed

Tip: Save even "good" intermediate stages as recipes - different profiles for different moods are perfectly fine!

Completely normal! Recognizing taste differences is a skill that develops over time.

Why this happens:

• Habituation: Your palate gets used to the taste
• Subtle changes: Small parameter adjustments = small taste changes
• Morning palate: Taste sensitivity isn't always consistent

Helpful strategies:

• Compare extremes: Try very fine vs. very coarse shot
• Take breaks: Wait 10 minutes between shots
• Drink water: Neutralize palate between tastings
• Focus on mouthfeel: Is coffee more watery, thicker, astringent?
• Note extremes: "Too sour" or "too bitter" is easier than nuances

The Espresso Tutor in the app helps you understand connections between parameters and taste.

Yes, Coffee Rings offers comprehensive export options:

• Individual recipes: Export specific recipes as files
• Entire library: Export your complete recipe cookbook
• Direct sharing: Share recipes as ZIP file with parameters and image

How it works: In recipe view, find export and sharing options. Choose whether to save file locally or share directly with others.

Backup & sync: On Apple devices, iCloud can sync recipes into your private iCloud database (CloudKit) if you allow Coffee Rings to use it. You can switch sync off or reset it anytime via Settings → Apple ID → iCloud → Apps using iCloud → Coffee Rings. On Android devices, the operating system may back up app data through Android backup and restore it after reinstalling the app or moving to another device when this is enabled in device settings.

Languages: Coffee Rings is currently available in German and English. Language is automatically chosen based on your system settings.

Regional settings: On first app launch, Coffee Rings detects your system region and automatically sets:

• Temperature: °C or °F
• Weight: Grams or ounces (metric/imperial)
• Currency: For price calculations with beans

Customizable: All these settings can be changed anytime in the app if automatic detection doesn't fit.

Additional languages are planned, depending on user feedback and demand.

The app is specifically designed for portafilter machines, but the knowledge is transferable.

Direct use: Optimized only for portafilter/espresso machines.

Knowledge transfer possible: The Espresso Tutor explains fundamental physics:

• Temperature effects: On sweetness, acidity, bitterness, balance, body
• Grind effects: Coarser vs. finer and their impact
• Extraction time: How duration influences taste
• Ratios: Understanding coffee-to-water ratio

Application to other methods:

• V60/Pour-over: Adjust grind and pouring speed
• French Press: Optimize time and grind
• Camping espresso: Refine temperature and ratios

The physics remains the same - only the application changes!

Your data is stored locally by default on your device. Coffee Rings doesn't operate any servers.

On Apple devices, iCloud/CloudKit can additionally sync recipes into your private Apple database if you allow Coffee Rings to use it. On Android devices, the operating system may back up and restore app data through Android backup when this is enabled on your device.

Storage & backup options:

• Local app storage: Fully offline usage
• iCloud/CloudKit: Optional sync on Apple devices in your private Apple database, controlled in system settings
• Android backup: System-controlled backup on supported Android devices, controlled through Android or Google settings
• Device backups: Depending on the platform, app data may be included in operating-system backups
• No own servers: Coffee Rings does not operate its own servers for your app data

The developer has no access to local app data, iCloud data, or Android backups.

No, never. I have no access to:

• Your shot data
• Saved recipes
• AI prompts or responses
• Tasting notes
• Usage statistics

I only see personal information if you actively contact me by email. Coffee Rings uses no analytics, no tracking, no telemetry.

When you use AI features, your shot parameters and tasting notes are sent directly from your device to OpenAI and are authenticated with your personal API key.

Important:

• Your API key stays in the protected app storage of the respective platform. On Android, it is stored in encrypted SharedPreferences; on Apple devices, it is stored in protected app storage and, if enabled, in your private iCloud backup
• I as the developer never see the API key or the transmitted data
• You control costs through your own OpenAI account
• Communication runs directly between your device and OpenAI, and Coffee Rings doesn't store AI responses on external servers

More details about AI usage →

Absolutely not! Coffee Rings works without AI and offers all core features.

The offline knowledge base:

• Suggests targeted changes based on your parameters
• Works without internet for the core features
• Costs nothing extra
• Is completely sufficient for most users

AI is just an option: For users who write very detailed notes or want to analyze experimental shots.

AI usage is billed by OpenAI according to your account and chosen model. In typical use, costs per call are a little over a cent.

Realistic cost calculation: Even if you dial in an entire 1kg bean package, AI costs are minimal:

• 1000g ÷ 18g per shot = 55 possible shots
• 55 AI calls × ~1 cent = about 60 cents per package
• Reality: You usually need only 3-5 attempts for good taste
• Actual costs: approximately 3-7 cents per bean package

Cost transparency:

• Coffee Rings charges no additional fee
• You see all costs directly in your OpenAI dashboard
• You can set spending limits anytime
• No additional Coffee Rings fees or subscriptions; OpenAI bills optional AI usage directly through your OpenAI account

Step-by-step:

1. Create OpenAI account at platform.openai.com
2. Generate API key in your dashboard
3. Enter in Coffee Rings Settings → AI Features → Add API Key
4. Start with a low spending limit ($5-10) to control costs

GPT-5.1 will be used with our optimized prompt.

Yes. Coffee Rings is available on Google Play. The iOS version currently offers the broader feature set, while the Android version is being expanded step by step. The core features for documenting and evaluating espresso shots are already available.

Your feedback is very valuable! Coffee Rings is continuously improved, and user feedback is the best way to make the app better for everyone.

How you can help:

• Feature requests: Describe concrete use cases and how a feature would improve your workflow
• Improvement ideas: Even small details can make big differences
• Unusual behavior: If something doesn't work as expected

Contact: Write to me via Support with details about:

• iOS or Android version and device model
• Description of behavior or request
• Screenshots if helpful

This way we improve Coffee Rings together for all users!