High-Low Method Calculator

The high-low method calculator turns two historical cost observations into a simple mixed-cost model. Enter the total cost and activity level from the highest-activity period, the total cost and activity level from the lowest-activity period, and the number of units you want to estimate. The result is variable cost per unit, estimated fixed cost, variable cost at the target volume, and total cost at that target volume.

This tool is for cost behavior analysis. It helps managers estimate how a utility bill, maintenance cost, shipping department, production support cost, call center, delivery route, or service department may change as activity changes. It is different from a break-even calculator, which uses fixed cost and contribution margin to find the no-profit sales level. It also differs from the gross margin calculator and operating margin calculator, which summarize profitability after costs have already been classified.

What the high-low method means

Many business costs are mixed. Part of the cost is fixed within a relevant range, and part changes with activity. A factory’s maintenance department may need a base staff level even when production is low, but extra machine hours can add parts, overtime, and contractor charges. A delivery operation may have vehicle leases and insurance that do not change each week, plus fuel and driver time that rise with miles or orders. The high-low method estimates those two pieces using only the highest and lowest activity observations.

The key word is activity. Activity might be units produced, labor hours, machine hours, shipments, invoices processed, service calls, rooms cleaned, or miles driven. The highest point should be the period with the highest activity driver. The lowest point should be the period with the lowest activity driver. Do not choose the highest and lowest total costs unless those are also the highest and lowest activity levels.

Formula

The calculator first estimates variable cost per unit:

$\text{variable cost per unit} = \frac{\text{high activity cost} - \text{low activity cost}}{\text{high activity units} - \text{low activity units}}$

Then it estimates fixed cost from each point and averages the two values:

$\text{fixed cost from high point} = \text{high activity cost} - \left(\text{variable cost per unit} \times \text{high activity units}\right)$

$\text{fixed cost from low point} = \text{low activity cost} - \left(\text{variable cost per unit} \times \text{low activity units}\right)$

$\text{estimated fixed cost} = \frac{\text{fixed cost from high point} + \text{fixed cost from low point}}{2}$

Finally it estimates total cost at the target volume:

$\text{total cost} = \text{estimated fixed cost} + \left(\text{variable cost per unit} \times \text{target units}\right)$

The form rejects entries where the high and low activity units are equal, because the denominator would be zero.

Worked example

Use the default inputs:

Calculate the variable cost:

$\text{variable cost per unit} = \frac{\$540{,}000 - \$315{,}000}{18{,}000 - 10{,}000} = \frac{\$225{,}000}{8{,}000} = \$28.125$

Calculate fixed cost from the high point:

$\text{fixed cost from high point} = \$540{,}000 - \left(\$28.125 \times 18{,}000\right) = \$33{,}750$

Calculate fixed cost from the low point:

$\text{fixed cost from low point} = \$315{,}000 - \left(\$28.125 \times 10{,}000\right) = \$33{,}750$

The average fixed cost is also $33,750. At 20,000 target units, variable cost is $28.125 multiplied by 20,000, or $562,500. Add the estimated fixed cost and the primary result is $596,250 total cost at 20,000 units. Its note expresses the model as $33,750 plus $28.13 times units, with display rounding applied to the per-unit cost.

How to use the estimate

Use the high-low result as a quick cost equation, not as a final budget by itself. If the target volume is inside the range between the high and low observations, the estimate is an interpolation. If the target volume is above the high point or below the low point, the estimate is an extrapolation and riskier. Step costs can break the model. A warehouse may need a second supervisor after 25,000 orders, a delivery fleet may need another truck after a mileage threshold, and a production line may pay overtime after normal capacity is reached.

The estimate is often useful before a more formal analysis. A manager can test whether fixed cost is large enough to pressure break-even volume, whether a product still supports a healthy gross margin, or whether a planned expansion might improve operating margin. The numbers also support scenario planning: change the target units and watch the variable portion rise while fixed cost stays constant.

Caveats and quality checks

Because the method uses only two observations, unusual periods have outsized influence. Exclude months with strikes, storm damage, emergency repairs, launch costs, discontinued product cleanup, or accounting reclassifications unless those events are expected to recur. Make sure both observations use the same activity driver and the same cost definition. If one point includes freight and the other excludes freight, the slope will not measure true variable cost.

Also check whether the activity driver is causal. Payroll department cost may correlate with headcount better than sales dollars. Maintenance cost may correlate with machine hours better than units if products use machines differently. Choosing the right driver matters more than the arithmetic.

Sources

Source version: issuer pages current when accessed July 9, 2026; no unstated effective year is assumed.

• OpenStax, Principles of Accounting, Volume 2 — open managerial-accounting treatment of cost behavior and estimation.