Welcome to FluxCentage

FluxCentage calculates the exact quantity of active ingredient needed to prepare a concentration-based solution — fertilisers, pesticides, disinfectants, or any product specified as a percentage. Enter the concentration and volume, and the app tells you precisely how much to measure out.

Interface Layout

Quick Start

1. Open the Calculator tab. Tap the concentration field and type the percentage specified on your product label (e.g. 0.5).
2. Select a volume preset (10 L, 20 L, 50 L, 100 L) or tap the custom field and type your own volume.
3. Choose ml or g depending on whether your product is liquid or solid. (The app assumes a density of 1 g/mL for liquids.)
4. The Result card updates instantly. It shows the quantity to measure and the mixing formula.
5. Tap Save Dosage to name and store the calculation for future reference.

Calculator

The Calculator tab is the core of FluxCentage. All inputs update the result in real time — no submit button needed.

Concentration Input

The concentration field accepts values between 0 and 100 (percent). You can type directly into the field or use the slider below it.

• Tap the field and type a value. The % suffix is decorative — do not include it.
• Values above 100 % are rejected with an inline error message.
• Negative values are rejected similarly.
• The slider and field stay in sync: moving the slider updates the field and vice versa.

Unit of Measure

Use the two pill buttons below the concentration card to select the output unit:

Volume Input

Tap one of the preset pills (10 L, 20 L, 50 L, 100 L) for common tank sizes, or tap the custom field and type any positive number. The volume is always in litres.

• The last volume you entered is remembered between sessions.
• Selecting a preset clears the custom field and vice versa.

Result Card

The result card shows the calculated quantity in large type, the selected unit, and a plain-language formula line: "Mix X ml in Y litres of water."

Result Formatting

The result is rounded automatically to keep the display readable:

Reset

The Reset button at the bottom of the calculator screen clears the concentration field and result. Volume and unit preferences are kept so you can start a fresh calculation without re-entering your tank size.

Formula

The underlying formula is:

quantity = (concentration% / 100) × volume_L × 1000

This gives the result in millilitres (or grams at 1 g/mL density). The calculation happens entirely on-device — no network connection is required.

Concentration Slider

The slider beneath the concentration field provides a visual, touch-friendly way to adjust the percentage. Four scale pills below the slider set the active range, controlling both the slider limits and the decimal precision of the displayed value.

Ranges & Precision

Each range is divided into exactly 100 equal steps. Tick marks appear at 0 %, 25 %, 50 %, 75 %, and 100 % of the active range as visual reference points.

Switching Ranges

Tap a scale pill to switch the active range. If the current concentration value falls within the new range it is preserved; otherwise it is clamped to the new maximum. The selected range is remembered between sessions.

Saved Dosages

The Saved Dosages tab stores named calculations so you can recall and reuse them without re-entering values each time.

Saving a Dosage

1. Complete a calculation on the Calculator tab.
2. Tap Save Dosage on the result card.
3. Type a descriptive name in the save panel (e.g. "Tomato feed — 10 L").
4. Tap Save. The dosage appears at the top of the Saved Dosages list.

Browsing & Searching

The list displays all saved dosages sorted by most recently created. Each card shows:

• The dosage name
• Concentration %, volume (L), and quantity with unit
• A copy icon to copy the quantity to the clipboard
• A delete icon to remove the entry

Use the search bar at the top to filter by name. The stats row below the search bar shows the total number of saved dosages and the database size.

Bulk Selection

Tap the checkbox on any dosage card to enter bulk-selection mode. Additional checkboxes appear on all cards. A share bar slides up from the bottom showing the count of selected items.

Menu Actions

Tap the three-dot menu icon in the top-right corner of the Saved Dosages screen for additional options:

Recipes

A Recipe combines multiple saved dosages into a single named plan for a specific solution volume. Use recipes when you routinely mix several products at once — for example, a weekly foliar feed that includes a fertiliser, a trace-element supplement, and a pH adjuster.

Creating a Recipe

1. Go to the Recipes tab.
2. Tap the green + button (bottom-right corner).
3. Enter a recipe name and the target solution volume.
4. Add the desired dosage components from your saved dosages list.
5. Save the recipe. It appears in the Recipes list with a volume badge and component count.

Recipe Cards

Each recipe card shows:

• The recipe name
• A volume badge (e.g. 10 L) in the brand accent colour
• The number of component dosages (e.g. "3 components")
• A share icon and a delete icon
• A checkbox for bulk selection

Bulk Selection & Sharing

Bulk selection on recipes works identically to the Saved Dosages tab. Select one or more recipe cards to reveal the share bar. Use the QR or Share buttons to send selected recipes to another device or person. Use the red Delete button to remove selected recipes.

Menu

The three-dot menu on the Recipes tab contains a Delete All option with a confirmation dialog.

QR Sharing

FluxCentage can encode saved dosages (or recipes) into a QR code so you can share them with another device by simply showing the screen and scanning.

Generating a QR Code

1. Open the Saved Dosages (or Recipes) tab.
2. Select one or more entries using the checkboxes.
3. Tap the QR button in the share bar that appears at the bottom.
4. A dialog opens showing the generated QR code. Show this to the receiving device.

Scanning a QR Code

1. On the receiving device, open the Saved Dosages tab.
2. Tap the three-dot menu → Scan QR Code.
3. Point the camera at the QR code displayed on the sending device.
4. Valid codes are detected automatically. The imported dosages are added to the list and a toast confirms the count.

Invalid or Unrecognised Codes

If the camera detects a QR code that was not created by FluxCentage, a red error banner appears at the bottom of the scan screen. The scanner continues running — you can try another code or tap the back button to cancel.

Duplicate Prevention

If you scan a code that contains entries already in your list, only the new ones are added. A toast message explains the outcome:

• "All entries already saved" — no new items imported.
• "Imported 1 dosage" or "Imported N dosages" — count of newly added items.

Export & Import

Use file-based export and import to back up your dosages, move them to a new device, or share large collections that would exceed QR code capacity.

Exporting All Dosages

1. Open the Saved Dosages tab.
2. Tap the three-dot menu → Export All as File.
3. The app creates a .json file containing all saved dosages and opens the system share sheet.
4. Choose a destination: save to Files, email, send via messaging, etc.

Importing from a File

1. Open the Saved Dosages tab on the receiving device.
2. Tap the three-dot menu → Import from File.
3. The file picker opens filtered to .json files. Select the previously exported file.
4. The app validates the file format and adds new entries. Duplicates are skipped automatically.

File Format

Export files are compact JSON with the following structure:

Web Platform

When using FluxCentage in a web browser, dosages are stored in browser local storage (SharedPreferences) rather than SQLite. Export and import work the same way — the file content and format are identical across all platforms.

Remove Ads Premium

The free version of FluxCentage displays a native ad card in the Saved Dosages list. Subscribing to the ad-free option removes all advertisements.

Enabling the Ad-Free Experience

1. Open the Saved Dosages tab.
2. Tap the three-dot menu → Remove Ads.
3. Follow the in-app purchase prompts to subscribe.
4. Once the purchase is confirmed, the ad card disappears immediately and does not return.

FAQ & Tips

Why does the result say 0 when I enter a low concentration?

Very low concentrations combined with small volumes can produce results below 0.001 ml/g, which rounds to zero at the displayed precision. Switch to a larger volume (e.g. 50 L or 100 L) to get a measurable result. For ultra-dilute solutions, consider making a stock solution at a higher concentration and then diluting further.

The density note says 1 g/mL — what does that mean?

When you select the ml unit, FluxCentage assumes the active ingredient has the same density as water (1 g/mL). For most water-soluble liquid concentrates this is a safe approximation. If your product has a stated density different from 1 g/mL, weigh the product on a scale and use the g unit for accurate results.

Can I use FluxCentage offline?

Yes. All calculations, storage, and QR generation happen entirely on-device. No internet connection is required for any feature except purchasing the ad-free subscription.

My language is not listed — what language does the app use?

FluxCentage follows your device's system language. Supported locales are English, Spanish (Spain & Latin America), French, German, Romanian, and Portuguese (Brazil). If your device language is not in this list, the app falls back to English.

How many dosages can I save?

There is no artificial limit. The database grows as you add entries; the stats row in the Saved Dosages tab shows the current database size so you can monitor storage usage.

I scanned a QR code but nothing was imported. What happened?

Check two things: (1) the code was generated by FluxCentage — codes from other apps are rejected. (2) Every entry in the code is already in your list — in that case, the toast reads "All entries already saved" and no action is needed.

Tips for faster workflows

• Set the slider range once to match your typical products and leave it — the app remembers it.
• Use preset volume pills for your standard spray tank size so you only need to type the concentration each time.
• Give saved dosages descriptive names like "Fungicide A — strawberries 0.3 %" so you can find them instantly with search.
• Build a Recipe for any multi-product mix you prepare regularly — a single card then reminds you of every component and amount.
• Use Export All as File after a season of use to keep an off-device backup of your dosage library.