Calculator Inputs
All fields support practical garden drying scenarios.Formula Used
Dry matter stays constant during drying. The calculator uses:
- Dry matter: DM = Wet × (1 − Mi)
- Final mass: Final = DM ÷ (1 − Mt)
- Water removed: Water = Wet − Final
- Energy: kWh = (Watts ÷ 1000) × Time
Time is estimated with a practical model that scales with water removed and tray area, then adjusts for temperature, airflow, thickness, and ambient humidity.
How to Use This Calculator
- Select a produce preset to preload typical moisture and temperature.
- Enter your wet load and confirm moisture targets for storage.
- Set trays, tray area, and layer thickness to match your setup.
- Adjust airflow and humidity to reflect your drying environment.
- Press Calculate to see yield, time, and cost above the form.
- Use CSV or PDF exports to save the latest batch summary.
Example Data Table
| Produce | Wet Load (kg) | Initial Moisture (%) | Target Moisture (%) | Trays | Temp (°C) | Estimated Time (h) |
|---|---|---|---|---|---|---|
| Herbs | 2.00 | 80 | 10 | 6 | 45 | 6.5 |
| Fruit slices | 3.00 | 85 | 15 | 8 | 60 | 8.0 |
| Mushrooms | 1.50 | 92 | 8 | 6 | 50 | 7.2 |
Batch Weight Planning
Fresh garden produce is mostly water, so a small wet load can become a small dry yield. Leafy greens often start near 90% moisture, herbs around 75–85%, and many fruits 80–88%. Entering the correct starting moisture helps the calculator predict water removal and the final stored weight with better accuracy. If you do not know moisture, start with a preset, then refine using your observed dry yield after a test.
Tray Capacity and Airflow
Drying performance depends on exposed surface area. The capacity check uses tray area, tray count, layer thickness, and a packing factor to estimate whether airflow will be restricted. For many home dehydrators, 0.10–0.15 m² per tray and 4–8 mm layers are a workable starting range for sliced produce. When loads exceed capacity, pieces shadow each other, humidity rises inside the chamber, and time increases sharply.
Temperature and Humidity Effects
Higher temperature speeds evaporation, but quality can drop if heat is excessive. Herbs commonly do well near 40–50°C, while fruits and roots often finish reliably around 55–65°C. Ambient humidity matters too: at 70% RH the same batch may take hours longer than at 40% RH because the air carries less additional moisture. If outdoor air is humid, use stronger airflow, smaller batches, or dry during drier daytime periods.
Time, Energy, and Cost Tracking
The time estimate scales with water removed and tray area, then adjusts for temperature, airflow, thickness, and humidity. Once time is estimated, energy is calculated as watts ÷ 1000 × hours. For example, a 600 W unit running 7.5 hours uses about 4.5 kWh; multiply by your rate to budget each harvest batch. Tracking cost helps compare methods, including sun pre-drying.
Storage Targets and Consistency
Target moisture is a storage decision. Many herbs are stable near 8–12%, and fruit leather or slices may be safer near 12–18% depending on thickness and sugar. Record your notes, rotate trays for even drying, and cool samples before sealing. Aim for repeatable thickness, similar piece size, and consistent tray spacing. Consistent loading and measured results reduce waste and improve shelf life.
FAQs
1) What is a good target moisture for dried herbs?
Most herbs store well near 8–12% moisture. They should feel crisp and crumble easily. Let them cool fully before sealing to avoid trapped humidity and condensation.
2) Why does the calculator warn about tray capacity?
Overloading reduces airflow and raises internal humidity. That slows drying, increases energy use, and can leave damp pockets. Reduce wet load, spread thinner, or add trays to restore airflow.
3) How do I choose initial moisture if I do not know it?
Start with a preset that matches your crop type. After one batch, compare the predicted dry yield with your actual yield, then adjust initial moisture until the estimates match your experience.
4) What thickness should I use for faster drying?
Thin, uniform layers dry fastest. Many slices perform well at 4–8 mm. Very thick pieces can case-harden outside while staying damp inside, especially in humid conditions.
5) How accurate is the time estimate?
It is a practical estimate, not a lab measurement. Fan strength, tray design, and crop structure can shift results. Use the first run to calibrate airflow and thickness for your specific dryer.
6) How can I reduce drying cost?
Improve airflow, avoid overloads, and keep thickness consistent. Pre-drain or pat-wet produce dry. Dry during lower humidity periods when possible, and batch similar items together to reduce stop-start cycles.
Downloads
Run a calculation first to store a session result.