Chiller Tonnage Estimator
Estimate the chiller tonnage a chilled-water loop needs from its flow rate and supply/return temperatures. Gets the load in tons, kW and BTU/h, adds a design margin, suggests the next standard chiller size and estimates compressor input power.
Input
Loop Temperatures
Design Allowances
Extra capacity added on top of the calculated load. Leave 0 for the bare load.
Typical water-cooled 0.5–0.7, air-cooled 1.0–1.3. Used for compressor input power.
Output
| Property | Value |
|---|---|
| No data yet | |
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/chiller-tonnage-estimator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"flow": "240",
"flowUnit": "gpm",
"supplyTemp": "44",
"returnTemp": "54",
"tempUnit": "f",
"margin": "10",
"efficiency": "0.6"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `chiller-tonnage-estimator` tool (Chiller Tonnage Estimator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
Embed widget
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<script src="https://iotools.cloud/embed.js" async></script>Drop this into your own page — free, no key required, just a link back.
| Cost per API/MCP call | From 5 credits |
|---|---|
| Need more credits? | View pricing |
Also available with
Guides
Estimate the cooling load of a chilled-water loop from its flow rate and supply/return temperatures, and turn it into refrigeration tons, kW and BTU/h. Add a design margin to get the capacity to specify, see the next standard chiller size up, and estimate compressor input power from a kW/ton efficiency.
How to use it
- Enter the chilled water flow and pick its unit (GPM, L/s or m³/h).
- Enter the supply (leaving) and return (entering) water temperatures and pick °F or °C.
- Optionally set a design margin and the chiller efficiency in kW/ton.
The formula
For water, tons = GPM × ΔT(°F) / 24. The tool works in SI internally: kW = flow (L/s) × 4.186 × ΔT(K), then divides by 3.517 kW per ton. One ton of refrigeration is 12,000 BTU/h.
Design margin and standard sizes
The Design Load is the calculated load plus your margin. The Suggested Chiller Size is the smallest common nominal capacity (5, 7.5, 10 … 1000 tons) that covers it. Manufacturers' real model sizes vary, so treat it as a starting point.
Limits
Assumes plain water. Glycol mixtures carry less heat per unit flow, so the real load is lower than shown for the same flow and ΔT. It does not model part-load behaviour, condenser conditions or pump heat.
Privacy
Everything runs in your browser — nothing you enter is sent anywhere.
Related tools
Size the load from the building side with the HVAC BTU Load Calculator, or check the air side with the Duct Velocity Calculator.