Extension of time calculator
This is claim arithmetic, not delay analysis. Enter each delay event, who caused it and whether it ran concurrently. Employer and neutral events earn time, employer events that are not concurrent also earn money, and the extension is capped at the gross delay you enter.
On this page
The rules this calculator applies
It does not analyse a programme, find a critical path or decide who is responsible. It adds up the days you enter, using the rules below, and your contract decides whether each rule holds for you.
- Employer-caused events earn time. If they are not concurrent they also earn money.
- Neutral events earn time only.
- Contractor-caused events earn nothing.
- A concurrent event is treated as time only, with no money. This is the tool's explicit assumption, not a statement of law.
- The extension cannot exceed the gross delay you enter, because a contractor cannot be given more time than it is actually late.
- A month is 30 days, so prolongation cost is the monthly time-related preliminaries × days ÷ 30.
Worked example
A project starts on 1 January 2026 with a 365-day duration. The gross delay at completion is 50 days. Time-related preliminaries are AED 90,000 a month.
| Event | Days | Caused by | Concurrent | Time | Money |
|---|---|---|---|---|---|
| Late site access | 20 | Employer | No | 20 | 20 |
| Design change | 15 | Employer | Yes | 15 | 0 |
| Exceptional weather | 6 | Neutral | No | 6 | 0 |
| Late materials | 10 | Contractor | No | 0 | 0 |
| Total | 51 | 41 | 20 |
From days to dates and money
The extension is 41 days, which is below the 50 days of gross delay, so no cap applies. Baseline completion is 1 January 2026 + 365 days = 1 January 2027. The revised date is 1 January 2027 + 41 days = 11 February 2027. The money days are 20, which is 20 ÷ 30 = 0.6667 months. Prolongation cost is AED 90,000 × 20 ÷ 30 = AED 60,000.
If the gross delay were 30 days, the extension would be capped at 30 days, and the money days would still be 20 because they cannot exceed the extension.
Where it fits
A claim needs notices, records and a programme that this page does not provide. The interim payments guide explains how settled amounts reach the certificate. In SupaJack Construct the contract value and payment terms sit in projects and tenders. Related: variation and payment certificate calculator, retention calculator, advance payment recovery calculator, VAT calculator, variation order calculator, delay damages calculator, bank guarantee cost calculator, price escalation calculator, BOQ line total calculator, subcontractor payable calculator.
Worked example
A project starts on 1 January 2026 and lasts 365 days. Late site access (20 days, employer) earns 20 days of time and money. A design change (15 days, employer, concurrent) earns 15 days of time only. Exceptional weather (6 days, neutral) earns 6 days of time. Late materials (10 days, contractor) earn nothing. The extension is 41 days, so completion moves from 1 January 2027 to 11 February 2027. Prolongation is AED 90,000 × 20 ÷ 30 = AED 60,000.
Questions people ask
Is this a delay analysis?
No. It is claim arithmetic only. It adds the days you enter by cause and does not analyse a programme or a critical path.
Why is the extension capped at the gross delay?
A contractor cannot be given more time than the project is actually late. The calculator takes the smaller of the days earned and the gross delay you enter.
What happens if I leave the gross delay blank?
Nothing caps the extension and the result says so. A typed 0 is different: it caps the extension at zero.
How are concurrent delays treated?
As time only, with no money. This is the tool's explicit assumption. Your contract and legal advice decide how concurrency is treated.
Do neutral events earn money?
Not in this calculator. Neutral events earn time only. Some contracts differ, so check yours.
Why 30 days to a month?
It is a stated convention so the result can be repeated. Use your contract's method if it states another.
Do overlapping events count twice?
They should not. Enter the days each event adds to the delay at completion, not the days it lasted.
What are time-related preliminaries?
Site costs that continue with time, such as supervision, site office and temporary facilities. Enter the monthly figure from your tender.
Does the calculator give legal entitlement?
No. Entitlement depends on your contract, notices given and evidence. Take advice before submitting a claim.
Can I use it for the contractor and the employer side?
Yes. Both sides can use the arithmetic to test a claim, with each side applying its own contract position.