Sector-based construction cost index calculator: Choosing construction index months — Worked Scenario

What this scenario actually checks

Choose the relevant high-level construction index before choosing months, and distinguish the indexed reference month from the date it was published. Compare registered monthly costs using only four high-level index series: overall construction, building, civil engineering, or electrical construction. Both month selectors are limited to observations loaded for the selected series. The built-in KICT series contains observations collected from a secondary dashboard alongside a published KICT reference; individual observations have not all been independently rechecked against the latest primary KICT release.

This walkthrough focuses on choosing construction index months. It follows the published tool inputs, not a new formula or an automatically verified legal, financial, medical or engineering determination.

Start by preparing the right inputs

Choose one of four index categories: overall construction, building, civil engineering or electrical construction. Base and comparison month menus display only registered observations, never future or unpublished months.

Before copying the example, confirm that each entered unit, date, dimension and default matches your real task. Changing only a visible number without revisiting its assumptions can change what the answer means.

• Choose one of four index categories: overall construction, building, civil engineering or electrical construction.
• Base and comparison month menus display only registered observations, never future or unpublished months.
• Enter a construction amount in whole KRW to calculate rate, estimated difference and adjusted amount.

Worked example with the calculator

Use the following input values: Overall construction cost index · Aug 2025 to Aug 2026 · KRW 100 million.

The example output is 130.91 → 138.74 · approximately +5.98% · approximately KRW 5.98 million increase. Uses registered overall construction index (2020=100), retaining the full index ratio in the calculation.

Treat this as a reproducible example, not a result to reuse with different measurements.

What can change the answer

Enter a construction amount in whole KRW to calculate rate, estimated difference and adjusted amount. KICT and ERIK publish different statistical indices. Results are estimates and do not determine contract E/S adjustments.

Can I select a comparison month that has not been published? No. Both month selectors are restricted to the loaded observations for the selected index series; a newer unpublished month cannot be calculated.

Does the index percentage automatically increase my contract amount? No. The percentage change is a reference calculation. Contract adjustments depend on the actual agreement, base dates and applicable rules, not the index ratio alone.

Before using the result for a real decision

For choosing construction index months, check the original measurements and input units, and save the assumptions alongside any number you share.

Where legal rules, official allowances, equipment ratings or contractual conditions matter, consult their current authoritative documents. An illustrative estimate is not a substitute for that verification.

• Reproduce the example before changing inputs
• Check all units and assumptions, including any default values
• Verify official or manufacturer-specific requirements outside the calculator