Free Tools

Calculators and reference guides for controlled-environment growing, brewing, climate, and compliance. No signup. Each one answers once — LoopString computes them live from your sensors and alerts you when they drift.

Grow & Cultivation

VPD Chart

Interactive, printable temperature × humidity grid coloured by growth-stage VPD zone.

VPD Calculator

Leaf VPD by growth stage, with the control action to bring it into the band.

PPFD / DLI Calculator

Convert light intensity and photoperiod to daily light integral, with crop targets.

Grow Room CFM Calculator

Size exhaust and circulation airflow for a sealed or vented grow space.

Climate & Psychrometrics

Dew Point Calculator

Dew point plus the dew-point spread and a condensation-risk read.

Wet Bulb Calculator

Wet-bulb temperature and evaporative-cooling potential for HVAC and greenhouses.

Brewing & Fermentation

Brix to SG Converter

Convert Brix ↔ specific gravity ↔ Plato in either direction.

Hydrometer Temp Correction

Correct a hydrometer reading for sample temperature vs calibration.

Keg Carbonation Calculator

Target CO2 volumes and beer temperature to the regulator PSI to set.

Fermentation Temperature Guide

Target fermentation temperatures by style and culture, ales to kombucha.

Compliance

HACCP Temperature Log

Free printable + CSV log template and a guide to frequency and corrective actions.

Temperature Mapping Guide

How to validate a cold room or warehouse and find the hot and cold spots.

Business

ROI Calculator

Estimate the payback of automating monitoring and control vs manual checks.

A calculator answers once. LoopString answers continuously.

These tools give you the number for one set of inputs. LoopString computes them live from the sensors on your Raspberry Pi, holds the target with edge control, and alerts you the moment it drifts.

Start Free See use cases