| Field | Example | Notes |
|---|---|---|
| Base Contract Amount | 150,000 | Core value of the agreement. |
| Tax Rate | 16% | Applied to selected taxable base. |
| Overhead Rate | 8% | Applied to direct costs. |
| Profit Rate | 10% | Applied to direct plus overhead. |
| Escalation | 5% / year, 12 months | Prorated by duration. |
| Contingency | 3% | Risk buffer for scope changes. |
The calculator builds a structured total from direct costs and layered adjustments. The simplified model is:
Overhead = Direct × Overhead%
Profit = (Direct + Overhead) × Profit%
Escalation = (Direct + Overhead + Profit) × Escalation% × (Months ÷ 12)
Contingency = (Direct + Overhead + Profit + Escalation) × Contingency%
Discount = (Direct + Overhead + Profit + Escalation + Contingency) × Discount%
Tax = (Taxable Base) × Tax% + Fixed Tax
Total = Direct + Overhead + Profit + Escalation + Contingency + Tax + Bonus − Discount − Penalty
Retainage is shown as withheld by default. If included, it is added to the total as a cost component.
- Enter the base contract amount and choose the contract currency.
- Add taxes and fixed charges such as service, administration, and insurance.
- Set overhead, profit, escalation, and contingency to match your policy.
- Add line items for change orders, reimbursables, or credits.
- Press Calculate to view the breakdown above the form.
- Use the download buttons to export CSV or PDF.
Contract cost structure and drivers
Direct cost starts with the base amount. Fees add predictable overhead. Line items capture change orders. Many projects show 5–20% variation from items alone.
Tax impact and taxable base choices
Tax can be a major driver. A 16% rate on a taxable base of 200,000 adds 32,000. Fixed levies add on top. Mark taxable items to match your rules.
Overhead and profit layering
Overhead is applied to direct costs. Profit follows on top of that subtotal. Example: 8% overhead on 150,000 equals 12,000. Then 10% profit on 162,000 equals 16,200.
Escalation and duration sensitivity
Escalation models price growth across time. It is prorated by months. A 5% annual rate over 18 months applies 7.5%. Longer terms increase exposure to market shifts.
Contingency and risk buffers
Contingency protects against uncertain scope. Many teams set 2–10%. Higher risk contracts use more. Keep it explicit. It helps governance and approvals.
Retainage and reporting outputs
Retainage is often withheld from payments. You can include it as a cost for cash planning. Export CSV for analysis. Export PDF for signoff packs. Use the graph to spot the largest drivers fast.
FAQs
1) What does the grand total represent?
It is the estimated full contract cost. It includes direct costs, rates, taxes, and adjustments. Discounts and penalties reduce the total. Bonuses add to the total.
2) How are line items handled?
Each item uses quantity times unit cost. Choose Add for charges. Choose Deduct for credits. Mark taxable items when they should be included in percentage tax.
3) Why does escalation use months?
Escalation is prorated by duration. Months are converted to years using months divided by twelve. This keeps short contracts from overstating annual increases.
4) Can I model retainage as a cost?
Yes. Enable the retainage checkbox. The calculator then adds retainage to the total. Leave it unchecked to treat retainage as withheld from payments.
5) What is the best way to compare scenarios?
Run one estimate per scenario. Adjust tax, overhead, profit, and risk. Use the breakdown table and graph to compare drivers. Export CSV to track multiple runs.
6) Are exports based on the latest calculation?
Yes. CSV and PDF export the most recent result saved in this session. Recalculate after edits, then download again to keep your records consistent.