How to Size a Commercial Coffee Roaster: Capacity Planning, Batch Economics & ROI

An engineering and financial formula guide for specialty roasteries: how to choose between 5 kg, 15 kg, 30 kg, or 60 kg batch capacities based on weekly volume and labor cost.

Sizing Pitfalls: Why 70% of New Roasteries Outgrow Their First Machine Within 18 Months

When opening a specialty roastery or expanding an existing café chain into wholesale roasting, machine capacity is the single most critical capital decision. Under-sizing forces your lead roaster to work 12-hour shifts roasting identical batches, escalating overtime labor costs and thermal wear on equipment. Conversely, over-sizing locks operating capital into oversized drum volumes that cannot roast small 2 kg green samples or seasonal micro-lots efficiently.

At RC-Tech, our thermal engineering desk uses an operational formula based on realistic production hours, gas consumption per kilogram, and green-to-roasted shrinkage rates.

The Weekly Batch Math: Calculating True Machine Capacity

To determine your ideal batch size, never calculate based on the rated batch capacity times 8 uninterrupted hours. Real-world commercial production involves: - 12 to 15 minutes of roasting time per batch. - 3 to 4 minutes of cooling tray retention and destoning. - 5 minutes of between-batch protocol (BBP) thermal stabilization.

This yields an average cycle time of 20 to 22 minutes per batch, or 2.7 to 3.0 batches per roasting hour.

Effective Monthly Throughput (kg) = Batch Charge (kg) × 2.8 batches/hr × Roasting Hours/Week × 4.2 weeks

Here is how RC-Tech equipment maps to commercial weekly production tiers:

| Target Volume | Recommended Roaster | Charge Size | Batches / Week | Weekly Roasting Hours | Monthly Capacity | |---|---|---|---|---|---| | 50 - 250 kg/week | RC CAST-5 | 5.0 kg | 10 - 50 batches | 4 - 17 hrs | Up to 1,000 kg | | 250 - 800 kg/week | RC CAST-15 | 15.0 kg | 17 - 54 batches | 6 - 19 hrs | Up to 3,500 kg | | 800 - 2,200 kg/week | RC CAST-30 | 30.0 kg | 27 - 74 batches | 10 - 26 hrs | Up to 9,000 kg | | 2,200+ kg/week | RC IS-60 / IS-120 | 60 - 120 kg | 37+ batches | 14+ hrs (Shift-based) | Up to 30,000 kg |

The Turnaround Point: When to Upgrade from 5 kg to 15 kg

A common threshold is whether to purchase the CAST-5 or the CAST-15.

If your wholesale roasting volume exceeds 200 kg per week, a 5 kg machine demands approximately 40 batches weekly, consuming roughly 14 hours of pure drum time plus green staging and bagging. In contrast, an RC CAST-15 completes 200 kg in just 14 batches (under 5 hours). The saved 9 hours of weekly skilled labor translates into over 450 hours per year—allowing your head roaster to focus on green sourcing, wholesale sales, and cupping quality control.

Utility & Facility Infrastructure Checklist

Before finalizing your roaster size, verify facility compatibility: 1. Gas Infeed Pressure: The CAST-5 requires natural gas at 20–25 mbar (or LPG at 30–50 mbar). Commercial 30 kg and industrial 60 kg plants require dedicated 3/4" to 1" high-flow gas piping. 2. Exhaust Vent Ducting: Flue pipe diameters range from 150 mm on CAST-5 up to 300 mm on IS-60. Avoid duct runs longer than 12 meters with more than two 90-degree elbows without an auxiliary booster fan. 3. Power Feeds: While ALP-1 and CAST-5 operate on standard single-phase 220V power, CAST-15, CAST-30, and IS-60 utilize 3-phase 380V/400V power to drive high-torque industrial worm gearmotors and independent cooling blowers.

Explore the machinery: RC ALP-1 · RC CAST-5 · RC CAST-15 · RC CAST-30 · RC IS-60 Industrial · RC IS-120 Industrial · RC DE30 Destoner · RC Destoner DE60 · RC Destoner DE120 · RC AFTB Coffee Gas Afterburner Series (AFTB1 / AFTB2 / AFTB3) · RC EXFUSION Smoke Dilution & Exhaust System · RC Industrial Coffee Cooling & Blending Mixer (MIX-60) · RC Premix Low-NOx Combustion Burner