Comparison

VPD Chart vs HydroponicsCalc

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • VPD calculation
  • Interactive VPD chart
  • Sensor integration
  • Zone organization
  • Dew point visualization
  • Grow Timeline
Features
Read full description

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/

About

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.

Highlights
  • 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
Features
Read full description

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

VPD Chart4 screens
HydroponicsCalc4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

Scorecard6 real differences · 4 level
VPD Chart versus HydroponicsCalc: the parameters behind the verdict, then further details
ParameterVPD ChartHydroponicsCalc
PriceFree — better$1.99
Rating4.5 (30 ratings)5.0 (1 ratings) — better
Positive reviews73.7% of reviews—
Number of ratings30 — better1
Update frequencyEvery 3 weeks—
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases — betterPaid
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS15.1 — better26.5
Further details — not scored
Size49 MB1 MB
Age rating4+4+
DeveloperINNOVO DEV S.R.L.Douglas Stieber

Customer experience

VPD Chart

All ratings30 ratings
Positive86.7%
Neutral3.3%
Negative10.0%
Written reviews19 reviews
Positive73.7%
Neutral0.0%
Negative26.3%

HydroponicsCalc

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

2 purchases

VPD Chart

Subscriptions2
  • VPD Chart Plus (monthly)3 Days trial$3.991 Month
  • VPD Chart Plus (annual)3 Days trial$29.991 Year
None

HydroponicsCalc

No in-app purchases

Questions

Is VPD Chart free?
VPD Chart is free to download, with in-app purchases available.
Is HydroponicsCalc free?
HydroponicsCalc costs $1.99, with no in-app purchases.
Which has better reviews, VPD Chart or HydroponicsCalc?
HydroponicsCalc is rated higher. VPD Chart averages 4.5 out of 5 from 30 ratings, while HydroponicsCalc averages 5.0 from 1 ratings.
Do VPD Chart or HydroponicsCalc have ads?
Neither VPD Chart nor HydroponicsCalc shows ads.

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