How this calculator works
Rendering is a per-frame calculation, so the total work is the per-frame time multiplied by the frame count. Splitting that work across machines divides the wall-clock time, provided each machine has a frame to work on and the scene and assets are available to all of them. The table uses a perfect split; real farms lose a little time to distribution, network transfer and the slowest frame at the end. Electrical cost is the power draw times the wall-clock hours, converted to kilowatt hours and multiplied by the tariff. A machine drawing 250 watts for 20 hours uses 5 kilowatt hours. The estimate covers the render machines only, not monitors, cooling or the rest of the studio.
Formula
total render time = render time per frame x number of frames / machines. machines needed = ceil(render time per frame x frames / target time). frames per hour = frames / total hours. energy (kWh) = power (W) x time (h) / 1000. cost = energy x price per kWh.
Worked example
A 2 minute per frame render of 2400 frames on 4 machines takes 120 x 2400 / 4 = 72,000 seconds, or 20 hours, and finishes 2400 / 20 = 120 frames per hour. To finish in 10 hours instead needs 120 x 2400 / 36,000 = 8 machines. At 250 watts each for 20 hours the 4 machines use 5 kilowatt hours, which costs 0.75 dollars at 0.15 dollars per kilowatt hour. One machine alone would take 80 hours.
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Frequently asked questions
Why does doubling the machines not always halve the time?
The calculation assumes a perfect split. In practice frames differ in render time, assets must be copied, and the final frame finishes alone. Small farms often see 70 to 90 percent scaling rather than 100.
What does a render farm cost to run?
Electricity is usually a small part of the cost. Cloud rendering is priced per core hour and includes hardware, cooling and management, so compare it against your own time and hardware rather than against the electricity bill alone.
Does the per-frame time include simulation?
No. Simulations, caches and denoising are separate steps and can dominate the schedule. Time each stage separately and add them, because simulation often cannot be split frame by frame.
How do I improve render time per frame?
Lower sample counts, smaller resolutions, simpler lighting and cached geometry all help. A denoiser can make a low-sample render usable, but check the result before relying on it for the final image.