VPD Chart vs HydroponicsCalc
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
VPD Chart
This app calculates Vapor Pressure Deficit (VPD) using air temperature, relative humidity, and canopy temperature. It offers real-time charting, sensor integration, and educational tools to understand plant growth environments. Organize data by zones and visualize dew point areas.
- VPD calculation
- Interactive VPD chart
- Sensor integration
- Zone organization
- Dew point visualization
- Grow Timeline
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The app calculates VPD using air temperature, relative humidity, and canopy temperature. View real-time VPD values on an interactive chart. Connect sensors for automated readings or manually input data via intuitive sliders and text inputs. Key features: • Interactive VPD chart with manual input • Default crop types • Organize charts by assigning them to different zones • Display spots that share the same VPD value • Zoom in and out of the VPD chart with a two-finger pinch and drag to pan around • VPD Target - long-press the chart to set a target VPD value • Dew point area visualization • Grow Timeline • Sync sensor historical data by importing it from sensor's app, via cloud APIs, or bluetooth • Explore sensor history by panning and zooming Supported bluetooth devices: • AC Infinity Cloudcom B2, A2, B1 • SensorPush: HT1, HT.w, HT.xw • Govee: H5051, H5072, H5074, H5075, H5100, H5101, H5102, H5103, H5104, H5105, H5174, H5177, H5179 • SwitchBot: Meter, Plus, Indoor Outdoor • Ruuvi: RuuviTag and RuuviTag Pro • Inkbird: IBS-TH1, IBS-TH1 Plus, IBS-TH2, IBS-TH2 Plus • ThermoPro: TP351, TP357, TP358, TP359 • VIVOSUN AeroLab THB1S • Shelly BLU H&T • Xiaomi Mijia 2 (LYWSD03MMC) (original and pvvx firmware) Supported devices with API connectivity: • Govee • Pulse • UbiBot • Ecowitt • Tuya • SensorPush Educational benefits: • Interactive Learning: Explore the dynamics of VPD based on changes in temperature and relative humidity by manipulating input sliders and animating the chart • Canopy - Air Temperature Link: Easily visualize and set values by linking canopy temperature to air temperature • Chart Bands Control: Toggle chart bands on/off (dew, under transpiration, prop, veg, flower, over transpiration) for a comprehensive understanding Included: 1 chart with manual input and grow timeline, device data sync & explore, default crops VPD Chart Plus subscription unlocks: • Unlimited charts • Automated VPD calculation by using sensors as the input data source • Background monitoring and Alerts (temperature, RH, VPD) • VPD history timeline, available on sensor-driven VPD charts • Custom crops Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
HydroponicsCalc
Manage your hydroponic garden with this comprehensive tool. Track reservoir levels, mix nutrients precisely, calculate pH and VPD, and document your grow with a journal and harvest log. Supports both US and metric units.
- Reservoir management dashboard
- Concentrate and EC mixing calculators
- pH and VPD calculators
- Grow journal with photo timeline
- Harvest log and ROI dashboard
- Light schedule tracker
- US & Metric unit support
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HydroponicsCalc is the complete grow-management companion for hydroponic gardeners — from beginners mixing their first concentrate bottles to experienced growers running multiple systems. RESERVOIR MANAGEMENT — FRONT AND CENTRE Your grow systems live on the home screen where you need them. See EC, pH, temperature, volume, and grow stage at a glance. Tap Log to record a reading or journal entry without digging through menus. Get change-due warnings before problems develop. CONCENTRATE MIXER Two modes for every workflow: • Bottle → EC: Enter bottle size and coverage target — get exact gram weights per component, dose rate (mL per gallon), and a live EC estimate. • Target EC → Dose: Enter your desired EC — get the mL-per-gallon dose you need. Supports MasterBlend 4-18-38, Jack's 321, General Hydroponics Flora Series, and more. Save your favourite configurations as reusable recipes. EC CALCULATOR Dial in nutrient strength with confidence. Input dose → see estimated EC. Input target EC → get required dose. An EC reference strip shows typical ranges from seedling to aggressive feeding, accounting for your source water baseline. pH CALCULATOR Enter current pH, target pH, and reservoir volume — get the exact mL of adjuster needed. Supports White Vinegar, Phosphoric Acid (pH Down), Potassium Hydroxide (pH Up), and custom adjusters with calibration mode. VPD CALCULATOR Vapour pressure deficit tracking with colour-coded zone feedback. Input air temperature, relative humidity, and leaf temperature offset — instantly see whether you're in the Too Humid, Seedling, Vegetative, Flowering, or Too Dry zone. GROW JOURNAL WITH PHOTO TIMELINE Document your grows with a date-sorted photo diary. Log observations, deficiencies, feedings, milestones, and harvests — with camera or photo library support. Export a full PDF archive of any journal. HARVEST LOG & ROI DASHBOARD Record wet weight, dry weight, and crop name for every harvest. Track cost-per-gram from your nutrient spend. See yield trends over time. Calculate energy costs from your light wattage and schedule. LIGHT SCHEDULE TRACKER Set your light schedule (18/6, 20/4, 12/12, or custom), log your flip date, and get an estimated harvest date with a countdown. US & METRIC Every calculator works in gallons/°F or litres/°C. One tap to switch — all values update instantly. NO SUBSCRIPTIONS. NO ADS. HydroponicsCalc is a one-time purchase. Everything is included. By HackerHomeLab.com
Screenshots
Verdict
The clearest difference is price: VPD Chart at Free against HydroponicsCalc's $1.99. VPD Chart also leads on ratings volume (30 vs 1) and iOS requirement (15.1 vs 26.5). HydroponicsCalc's advantage is rating (5.0 vs 4.5) and in-app purchases (none vs 2). On ads 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
VPD Chart is free to download; HydroponicsCalc costs $1.99 up front. VPD Chart sells 2 in-app purchases, starting at $3.99 per month. HydroponicsCalc asks for nothing beyond the download.
HydroponicsCalc holds the better App Store score, 5.0 against 4.5. That said, the two scores are not equally well evidenced: VPD Chart has 30 ratings behind it against 1, so its average is the more settled of the two.
| Parameter | VPD Chart | HydroponicsCalc |
|---|---|---|
| Price | Free — better | $1.99 |
| Rating | 4.5 (30 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 73.7% of reviews | — |
| Number of ratings | 30 — better | 1 |
| Update frequency | Every 3 weeks | — |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases — better | Paid |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 15.1 — better | 26.5 |
| Further details — not scored | ||
| Size | 49 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | INNOVO DEV S.R.L. | Douglas Stieber |
Customer experience
VPD Chart
HydroponicsCalc
In-app purchases
VPD Chart
- VPD Chart Plus (monthly)3 Days trial$3.991 Month
- VPD Chart Plus (annual)3 Days trial$29.991 Year
HydroponicsCalc
No in-app purchases
Questions
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Is HydroponicsCalc free?
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