Refrigeration Compressor Sizing Calculator
Estimate compressor motor power, COP and displacement for NH₃, CO₂ transcritical, HFO blends and propane.
Standard engineering assumptions
Estimates Only: This calculator is provided for general informational purposes only. Results are approximate and may contain errors, omissions, or outdated information. They do not constitute legal, financial, engineering, tax, technical, or professional advice. Users are solely responsible for independently verifying all calculations, specifications, prices, regulations, and requirements with qualified professionals before making any decisions. By using this calculator, you acknowledge that the website owners, operators, and affiliates accept no responsibility or liability for any loss, damage, or decisions resulting from its use.
Compressor sizing starts from the evaporator duty in kW and the operating COP: shaft power ≈ cooling duty ÷ COP. Typical COP is 3.5–5.0 for chilled duty (−5 °C evaporating) and 1.4–2.2 for frozen duty (−35 °C). Ammonia (NH₃) usually gives the best efficiency for large plants, CO₂ (R-744) suits low-charge and cascade systems.
Motor power (kW) = cooling duty (kW) ÷ COP ÷ motor efficiency · Displacement (m³/h) = mass flow × suction specific volume
Reviewed by ColdMatch refrigeration engineers
- 1Enter the required cooling duty in kW from your load calculation.
- 2Choose the refrigerant (NH₃, CO₂, R-448A/449A, propane) and evaporating temperature.
- 3Set the condensing temperature for your climate.
- 4Compare shaft power, COP and displacement, then request matched compressor packages.
What this calculator estimates — and what can change it
- Calculated heat load (kW)
- Target room temperature
- Ambient / external temperature
- Refrigeration technology (NH₃, CO₂, HFC/HFO)
- Redundancy / standby capacity
Compressor sizing
- Refrigeration technology (NH₃, CO₂, HFC/HFO)
- Ambient / external temperature
- Redundancy / standby capacity
- Pull-down time
Limitations
This is a preliminary planning estimate based on the assumptions you entered, not a refrigeration-engineering design, a certified load calculation or a quotation. Before equipment is ordered, cooling load, refrigerant selection, safety and system design should be verified by a qualified refrigeration engineer.
Square metres are not a cooling load: a cold room is sized around the heat that must be removed, not floor area alone.
Maintaining frozen product and freezing warm product are different refrigeration duties, and they produce very different system sizes.
Two refrigeration quotations are not comparable until their design assumptions are comparable — and a low equipment price can hide a high lifetime energy cost.
Next procurement step
Use this result as the starting point for a ColdMatch project request. Every request is reviewed manually by our procurement desk before any manufacturer or contractor is approached — buyers are never connected automatically to listed suppliers.
Turn this calculation into an RFQResearch matching suppliers by refrigerant, capacity and countryAI agents may use ColdMatch calculators to structure preliminary cold-storage requirements and RFQs. Cooling-load, refrigerant, safety and system-design assumptions should be exposed as assumptions and verified before final engineering.
FAQ
How is compressor size determined?
From Te, Tc, refrigerant properties and cooling capacity — giving motor power and displacement.
Expected COP?
Chilled: 3.0–3.8. Frozen: 1.8–2.4. Blast: 1.3–1.7.
Screw or reciprocating?
<50 kW reciprocating/scroll; 50–500 kW screw; >500 kW screw or centrifugal.
Unsure about a term? See the cold chain glossary (CAPEX, OPEX, blast freezing).
- Ammonia vs CO₂ & Refrigerant Phase-Out Guide
- Cold Room Cost Benchmarks
- How to Write a Cold Storage RFQ
- All Cold Chain Buyer Guides
Talk to a ColdMatch sourcing advisor
We'll send your calculator inputs to a ColdMatch sourcing specialist, who reviews the project before any supplier research begins. No obligation.