3D Render Time Calculator (animation frames, render farm & finish time)

Understanding the 3D render time calculator — concept and principle

Rendering an animation can take hours or days. This calculator estimates how long: it multiplies the number of frames by the render time per frame and spreads the work over the computers you have, so you can see the total machine time and when the last frame will be finished.

How it is calculated

Frames = length (s) × frame rate, rounded up

Total machine time = frames × time per frame

Frames per machine = ⌈frames ÷ machines⌉

Wall-clock time = frames per machine × time per frame

Render minutes per second of animation = time per frame × frame rate

• Time per frame is in minutes; frame rates of 24, 25, 30 or 60 fps.

The principle

An animation is a sequence of still images. Each one must be rendered, so total work is simply the number of frames times the work per frame. Frames are independent, so they can be shared between computers, a render farm. Because each computer renders whole frames, the machine with the most frames sets the finish time, which is why the frame count per machine is rounded up. Doubling the frame rate doubles the work for the same length of animation.

Worked example

Default inputs: 20 s at 24 fps, 3 minutes per frame, 2 computers.

1. Frames = 20 × 24 = 480.
2. Total machine time = 480 × 3 = 1,440 min = 24 hours.
3. Frames per machine = ⌈480 ÷ 2⌉ = 240.
4. Wall-clock time = 240 × 3 = 720 min = 12 h 00 min (12 hours).
5. Render minutes per second of animation = 3 × 24 = 72.

How to read the result

Use the wall-clock time to plan deadlines and the total machine time to estimate cloud render costs, which are often charged per machine-hour. Render a few test frames from the most complex parts of the shot, because time per frame can vary greatly with motion blur, particles, volumetrics and reflections. Add a margin for loading scenes, saving files and re-rendering problem frames.

Common mistakes

• Timing a simple frame and applying it to the whole animation.
• Forgetting that 60 fps needs 2.5 times as many frames as 24 fps.
• Ignoring compositing and encoding time after rendering.
• Assuming all machines are equally fast.

Frequently asked questions

How many frames are in 10 seconds at 30 fps?

300 frames.

Does doubling the machines halve the time?

Roughly, if they are equally fast and the frame count divides evenly.

How do I reduce render time?

Lower samples, use denoising, simplify lighting or optimise heavy effects.

Why is total machine time useful?

Cloud render services usually charge by machine time, so it estimates cost.

Sources: Arithmetic of frame-based animation: frames = duration × frame rate; total time = frames × time per frame; ceiling division over machines