Reference
Calculators & tools
Ten working calculators that turn the theory in this knowledge base into numbers for your own kitchen or dryer. Everything runs in your browser — no data is sent anywhere, and everything updates as you type.
These are planning estimates built on simplified models, calibrated with representative literature values. They are excellent for deciding whether an idea is sane and for spotting when something is wildly off. They are not a substitute for measurement — for anything you sell, verify with a moisture or water-activity meter and treat the numbers below as a hypothesis.
Batch maths
🧮 Moisture, yield and water-loss calculator
The workhorse. Given a fresh weight and the moisture before and after drying, it returns the final weight, the water removed, the mass retained and the fresh-to-dry ratio.
💧 Water activity estimator GAB isotherm
Converts between moisture content and water activity using a GAB sorption isotherm with representative parameters for each food class. Use it to check whether “dry enough” really is aw ≤ 0.60 — or to find the moisture content you need to reach a target aw.
GAB parameters used per class are representative literature values (Xm, C, K). Real isotherms vary with variety, ripeness, sugar content and temperature — a measured aw is always authoritative.
⏱️ Drying-time estimator
A first-order thin-layer model with an Arrhenius temperature term and a thickness correction, calibrated for 5 mm fruit slices at 60 °C. It will get you within roughly a factor of two for a new product — enough to plan a day.
🗂️ Dehydrator load and tray sizer
How many trays does a batch need, and when does a load become too heavy for the airflow you have? Enter the batch, the expected yield ratio, the loading density and the tray size.
Energy, cost and solar sizing
💡 Energy and cost calculator
What does a batch actually cost to dry? And is your dryer anywhere near the theoretical energy floor?
☀️ Solar dryer sizing calculator
Sizes a solar air collector for a daily batch: how much water must leave, how much energy that takes, and what collector area delivers it under your local sun.
Preparation and rehydration
🥣 Rehydration calculator
How much water to add to bring dried product back, and how long to soak it.
See the rehydration ratio table for product-specific times and methods.
🍯 Brix and brine mixer
Exact quantities for a sugar syrup or salt brine. Choose your units, state the water you will use, and it returns the solute required by weight.
🧪 Pretreatment dip scaler
Turns a pretreatment recipe into grams of solute for the volume you are actually using.
Sulfites must be declared above 10 ppm in most jurisdictions and can trigger reactions in sensitive people. See sulfites and allergens.
🔁 Unit and temperature converter
The three conversions that waste the most time in a drying kitchen: temperature, mass, and the wet-basis / dry-basis moisture trap.
Plan-a-batch wizard
These calculators, combined: answer six questions and get a complete drying plan with a printable bench card.
📈Batch tracker
Log weigh-ins during a run and plot your own drying curve against the predicted target weight.
📏Measurement & calibration
Verify the numbers you feed these calculators: thermometer calibration, loss-on-drying moisture, approximate water activity.
📄Templates & SOPs
Printable SOPs, batch records and logs — the paperwork side of the same process.
Quick reference card
Print this page, or copy these into your batch log.
| Quantity | Value to remember | Where it is used |
|---|---|---|
| Shelf-stability water activity | aw ≤ 0.60 | The goal of every drying run |
| Final weight formula | W₁ = W₀(100 − M₀)/(100 − M₁) | Yield, batch planning, doneness |
| Latent heat of water | ≈ 2.45 MJ/kg ≈ 0.7 kWh/kg | Energy planning, solar sizing |
| Real dryer efficiency | 20–50 % | Sanity-checking energy use |
| Thickness effect on time | time ∝ thickness (to thickness²) | Slicing decisions |
| Temperature effect on rate | ×2 per 10 °C in the falling-rate phase | Schedule adjustments |
| Jerky lethality | 160 °F / 165 °F poultry | Safety — non-negotiable |
| Jerky stability target | MPR ≤ 0.75 : 1 | Safety and shelf life |
| Wet → dry basis | Md = 100·Mw/(100 − Mw) | Comparing sources |
| Loading density | 2–6 kg fresh per m² | Tray loading and airflow |
| Storage target | ≤ 20 °C, ≤ 60 % RH, dark | Shelf life |