True Variable vs Step Variable Cost: Key Differences Explained
True Variable Cost changes in direct proportion to every unit you make or sell—more output, more cost, and vice versa. Step Variable Cost stays flat for a range of output, then jumps to a new higher level when activity crosses a threshold.
People confuse the two because both move with volume, but the movement feels different: a baker sees flour rise smoothly with every extra loaf, yet oven rental only spikes when the shop needs a second oven.
Key Differences
True Variable tracks each unit; Step Variable leaps only at set breakpoints. Think of hourly wages vs hiring an extra shift. The first climbs steadily, the second jumps when demand outstrips the current team.
Which One Should You Choose?
If output fluctuates daily, lean toward True Variable to stay flexible. If growth is lumpy and you can tolerate plateaus, Step Variable keeps budgeting simpler and avoids constant small changes.
Examples and Daily Life
Gasoline for a delivery van is True Variable—every mile burns fuel. A cloud-storage plan that jumps from 100 GB to 500 GB after you hit a limit is Step Variable.
Can a cost be both types?
Yes. A utility bill often has a base Step Variable fee plus a True Variable charge for each kilowatt used.
How do I spot the pattern on an invoice?
Look for steady line-by-line increases versus sudden jumps; the former signals True Variable, the latter Step Variable.