VFD Energy Cost Savings Calculator
Annual dollar savings from adding a VFD to a fan.
Enter your values
Enter the full-speed power in kW.
Enter the average vfd speed in % of full speed.
Enter the annual run hours in hr.
Enter the electricity rate in $/kWh.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Annual energy saved
- 52,031 kWh
- Annual cost savings
- $6764
- New average power
- 6.33 kW
- Percent power saved
- 57.8%
Quick answer
Annual savings equal the power reduction at reduced speed times annual run hours times the electricity rate.
Savings = (P1 - P1 x (N2/N1)^3) x hours x rate
At a glance
| What it does | Annual dollar savings from adding a VFD to a fan. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Full-speed power, Average VFD speed, Annual run hours, Electricity rate |
| Main output | Annual energy saved |
| Formula | Savings = (P1 - P1 x (N2/N1)^3) x hours x rate |
| Cost | Free — no sign-up, no download |
How to use the VFD Energy Cost Savings Calculator
- 1Enter the fan's full-speed power draw and the average speed it will run at with a VFD.
- 2Enter annual operating hours and your electricity rate.
- 3Read the annual energy and cost savings to help justify the VFD payback.
Inputs explained
- Full-speed power(kW)
- Enter the full-speed power in kW.
- Average VFD speed(% of full speed)
- Enter the average vfd speed in % of full speed.
- Annual run hours(hr)
- Enter the annual run hours in hr.
- Electricity rate($/kWh)
- Enter the electricity rate in $/kWh.
Worked example
Using the values the calculator loads with:
Inputs
- Full-speed power15 kW
- Average VFD speed75 % of full speed
- Annual run hours6000 hr
- Electricity rate0.13 $/kWh
Results
- Annual energy saved52,031 kWh
- Annual cost savings$6764
- New average power6.33 kW
- Percent power saved57.8%
Frequently asked questions
How do I find average VFD speed?
Use trend logs from an existing BAS, or estimate from typical load profiles for the application.
Does this include drive losses?
No — VFD and motor conversion losses are small (a few percent) and can be added as a simple derate if needed.
What do I need to enter into the VFD Energy Cost Savings Calculator?
Just 4 values: full-speed power, average vfd speed, annual run hours, electricity rate. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the VFD Energy Cost Savings Calculator work out the answer?
Annual savings equal the power reduction at reduced speed times annual run hours times the electricity rate. It applies the formula Savings = (P1 - P1 x (N2/N1)^3) x hours x rate and shows the working so you can check each step by hand.
Is the VFD Energy Cost Savings Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.