What Is a Provisional Quantity?
A provisional quantity is an estimated amount of work listed against a priced item in a construction contract — most often in a Bill of Quantities or schedule of rates — where the rate for that item is fixed at tender, but the quantity itself is only an estimate because it can’t be confirmed until the work is actually carried out and measured. Payment for that item is then calculated on the quantity actually measured on site, multiplied by the agreed rate, rather than on the original estimated figure.
Key takeaways
- A provisional quantity is an estimated, non-binding figure for how much of an item of work will be needed — the rate is fixed, but the quantity is not.
- It’s used where the true extent of the work can’t be confirmed until site conditions are exposed, such as excavation depth, rock removal or the extent of associated services.
- Payment is based on the quantity actually measured once the work is carried out, not the original provisional figure — a process called remeasurement.
- A provisional quantity is not the same as a provisional sum — one adjusts a quantity against a fixed rate, the other adjusts an entire dollar allowance.
- Careful site measurement and record-keeping are what make a provisional quantity item easy to reconcile rather than a source of dispute.
What is a provisional quantity?
A provisional quantity is a measured line item in a contract — typically within a Bill of Quantities or a schedule of rates — where the description and rate are fixed, but the quantity shown is only an estimate. It appears because the design intent for that item is already settled, yet the true extent of the work genuinely cannot be confirmed until it is exposed or carried out on site.
The item is usually marked clearly as provisional (often literally “Prov.” or flagged with an asterisk) with an estimated quantity included so tenderers can price a comparable total at tender stage. The contract makes clear, however, that final payment for that item is based on the quantity actually measured during construction, multiplied by the agreed rate — not the original estimate.
Provisional quantities turn up most often on civil, infrastructure and larger commercial contracts that use a measured Bill of Quantities or schedule of rates, though the same principle applies on smaller jobs wherever an item — like excavation depth pending a geotechnical report — genuinely can’t be measured accurately before work starts.
In plain terms
A provisional quantity is a “best guess so far” number attached to a real, priced item — the price per unit is locked in, but the final bill for that line only firms up once the actual amount of work is measured.
What triggers a provisional quantity
A provisional quantity is used wherever the item itself is certain but its true extent depends on conditions that can only be confirmed once the work is under way.
- Excavation and earthworks, where the true depth, rock content or extent of unsuitable material can’t be confirmed until the ground is opened up.
- Underground services or utilities, whose exact length or condition is unknown until they are exposed.
- Structural or civil items — such as piling depth or retaining wall length — that depend on geotechnical conditions confirmed during construction.
- Any measured item where the design is fixed in principle but the site conditions genuinely can’t be surveyed accurately before work starts.
How a provisional quantity works in the contract
In a Bill of Quantities or schedule of rates, the item is listed with its description, unit, an estimated quantity and the tendered rate, but flagged as provisional so everyone reading the document knows the quantity is not firm. The contract wording then states plainly that payment for that item is based on the quantity measured once the work is carried out, not the estimate shown at tender.
This can sit within an otherwise lump-sum contract, as a carve-out for the handful of items that genuinely can’t be fixed in advance, or it can apply across a whole civil or infrastructure contract priced on a full remeasurement basis, where every item is subject to the same as-built measurement.
Because only the quantity is provisional and not the rate, a well-drafted item leaves little room for argument about price — the negotiation, if there is one, is almost always about how the final quantity was measured, not what it should cost per unit.
How a provisional quantity is remeasured and paid
Once the work covered by a provisional quantity item is carried out, it is measured on site — often by survey, as-constructed drawings or agreed site measurement — and the actual quantity is multiplied by the rate fixed at tender to arrive at the true value of that item. The difference between the original estimate and the actual measured amount is then reflected in the next progress claim or the final account.
This reconciliation is usually straightforward precisely because the rate was never in dispute — the only variable being resolved is quantity, which a proper site measurement settles cleanly.
| Item | Description | Provisional qty | Rate | Actual qty | Adjustment |
|---|---|---|---|---|---|
| 4.1 | Rock excavation | 150 m³ | $85.00 | 210 m³ | +$5,100 |
| 4.2 | Sub-soil drainage pipe | 80 m | $62.00 | 65 m | -$930 |
Who measures and confirms a provisional quantity
On civil and larger commercial contracts, a superintendent or quantity surveyor typically measures or jointly certifies the as-built quantity with the contractor, often supported by a formal site survey or as-constructed drawings. On smaller jobs, the builder and client agree the measurement directly, ideally backed by photos, dockets or a simple site record.
Whoever confirms the quantity, good record-keeping as the work proceeds — survey data, delivery dockets, photographs — is what keeps the reconciliation clean and avoids it turning into a dispute at the end of the job.
It is good practice to agree the measurement method in writing before the provisional item is even started, rather than leaving it to be worked out once the work is already done — a simple pre-agreed rule for how depth, length or volume will be measured avoids most disagreements entirely.
Provisional quantity vs provisional sum vs variation
These three terms all describe a figure that isn’t firm at the time of signing, but each one fixes a different part of the price:
- Provisional quantity vs provisional sum — a provisional quantity adjusts the measured amount of an already-priced, already-designed item; a provisional sum is a dollar allowance for work that isn’t designed or specified at all yet.
- Provisional quantity vs variation — remeasuring a provisional quantity against the agreed rate isn’t a variation, because the item and its rate were always part of the contract; a variation changes the scope itself.
- Provisional quantity vs estimate — an estimate is one party’s prediction of total cost; a provisional quantity is a specific, contractually defined figure attached to one line item, always subject to remeasurement under the contract terms.
Common mistakes with provisional quantities
Most disputes over provisional quantities are avoidable and come down to a handful of recurring gaps.
- Treating the provisional quantity shown at tender as a guaranteed final figure, rather than an estimate subject to remeasurement.
- Not agreeing the measurement method — survey, as-built drawings or site dockets — up front, which turns reconciliation into a dispute.
- Failing to keep site records as work proceeds, making it hard to substantiate the actual quantity later.
- Confusing a provisional quantity item with a provisional sum item when preparing or checking a Bill of Quantities.
How My Trade Hub helps with provisional quantities
My Trade Hub’s estimation engine flags provisional items separately within the Bill of Quantities it generates from your plans, so everyone can see at a glance which lines are firm, measured quantities and which are estimates still to be confirmed on site.
Because the underlying measured takeoff is retained rather than thrown away after tender, updating a provisional quantity line the moment a survey, geotechnical report or site measurement comes in recalculates that item — and any downstream totals — in minutes, as part of an estimating workflow built to run 60-75% faster than manual estimation.
Frequently asked questions
What is a provisional quantity in a construction contract?
A provisional quantity is an estimated amount of work listed against a priced item in a contract — usually within a Bill of Quantities or schedule of rates — where the rate is fixed but the quantity is only an estimate, to be confirmed once the work is measured on site.
What is the difference between a provisional quantity and a provisional sum?
A provisional quantity adjusts the measured amount of an item that is already designed and priced at a fixed rate. A provisional sum is a dollar allowance for an entire item of work that isn’t yet designed or specified at all. One resolves a quantity; the other resolves a whole scope.
How is a provisional quantity paid?
Payment is based on the quantity actually measured once the work is carried out, multiplied by the rate agreed at tender — not the original provisional estimate. Any difference between the estimate and the measured quantity is reflected in the progress claim or final account.
Who measures a provisional quantity?
On larger civil or commercial contracts, a superintendent or quantity surveyor typically measures or certifies the actual quantity, often using a site survey or as-constructed drawings. On smaller jobs, the builder and client agree the measurement directly, ideally supported by photos or site records.
Is a provisional quantity the same as an estimate?
Not quite. An estimate is a general prediction of cost. A provisional quantity is a specific, contractually defined figure attached to one priced line item, with a fixed rate and a clearly stated remeasurement process once the work is done.
Can a provisional quantity increase the contract price?
Yes. If the quantity of work actually measured is more than the provisional estimate, the value of that item increases accordingly at the same agreed rate, and the additional amount is added to the contract price through the reconciliation process.
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