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Construction Cost and Labour Calculator

How to Calculate Construction Labour Cost: Hours, Cost per Unit and Productivity

Labour is often the biggest and least predictable cost on site. Learn how to work out total labour hours, labour cost, cost per unit and productivity per worker for bricklaying, excavation and concrete, with worked examples and a free calculator.

Last updated 7 November 2026

Why labour needs its own calculation

Materials can be priced from a quantity and a supplier quote, but labour depends on crew size, time, skill and how well the work is organised. A small error in estimated hours becomes a large error in cost, and a gang that works slower than planned eats into your margin quietly.

A simple, repeatable calculation lets you price work, compare crews and check progress against the estimate. KaelSite’s free Construction Cost and Labour Calculator works out hours, cost, cost per unit and productivity from a few inputs.

The formulas

  • Total labour hours = workers × hours per day × days
  • Total labour cost = total labour hours × hourly labour cost
  • Cost per unit = total labour cost ÷ units of work completed
  • Productivity per worker-day = units ÷ (workers × days)
  • Productivity per labour-hour = units ÷ total labour hours

Use decimals for part-days, for example 2.5 days.

What goes into the hourly rate?

Use an all-in rate if you want the cost to be realistic. Basic pay is only part of it. An all-in rate typically includes:

  • Employer’s National Insurance and pension contributions
  • Holiday pay
  • Tools, PPE and training
  • Supervision and overheads

If you use basic pay only, your cost per unit will look cheaper than it really is.

Worked examples

All rates and quantities below are examples only. Use your own figures.

1. General labour
4 workers × 8 hours × 5 days = 160 labour hours
At £25 per hour: 160 × 25 = £4,000

2. Bricklaying
2 bricklayers working 8 hours a day for 4 days, laying 2,400 bricks, at an all-in £32 per hour:
Hours = 2 × 8 × 4 = 64
Cost = 64 × 32 = £2,048
Cost per brick = 2,048 ÷ 2,400 = about £0.85
Productivity per worker-day = 2,400 ÷ (2 × 4) = 300 bricks
Productivity per labour-hour = 2,400 ÷ 64 = 37.5 bricks

3. Concrete pour
6 workers on a 1-day pour of 40 m³ at 8 hours and an all-in £26 per hour:
Hours = 6 × 8 × 1 = 48
Cost = 48 × 26 = £1,248
Cost per m³ = 1,248 ÷ 40 = £31.20
Productivity per worker-day = 40 ÷ (6 × 1) = 6.7 m³

Using the results

  • Pricing: multiply cost per unit by the quantity for similar work, then add materials, plant and margin.
  • Comparing gangs: the same job done by two crews shows which is faster and cheaper per unit.
  • Tracking: compare actual hours from timesheets with the estimate while the work is under way.
  • Pricing extras: a known cost per unit helps you price variations quickly and fairly.

Check productivity against your own records

Published outputs for bricklaying, excavation and concrete vary a lot with the job, access, weather and crew. The most reliable benchmark is your own past work. Record the units completed and hours worked on each job, then use those figures for the next estimate.

What the calculator does not include

This calculator covers labour time and cost only. Materials, plant, delivery, waste disposal and margin are separate. If you want an approximate all-in gang rate, you can fold plant costs into a higher hourly rate, but keep a separate figure when you can so you can see where money goes.

Common mistakes

  • Using basic pay instead of an all-in rate. This makes every unit look cheaper than it is.
  • Forgetting non-productive time. Travel, setting out, breaks, waiting for materials and weather all use hours.
  • Using one rate for a mixed crew. If the gang has different pay levels, use a blended average rate.
  • Entering the wrong units. Bricks, m², m³ and metres are not interchangeable.
  • Relying on optimistic outputs. Estimates based on best-day performance are usually missed.
  • Leaving out supervision. Someone must manage, check and sign off the work.

UK points to know

Working hours matter when you plan crews. Under the Working Time Regulations, most workers’ average working week is limited to 48 hours unless they have opted out, so long days cannot simply be stacked up to hit a programme. CDM 2015 also requires planning, welfare and coordination of the work, which takes time that should be reflected in your estimate. For benchmark cost data across the industry, services such as BCIS publish rates.

Frequently asked questions

How do I calculate total labour hours?
Multiply workers by hours per day by days. For example, 4 workers × 8 hours × 5 days is 160 labour hours.

How do I calculate total labour cost?
Multiply labour hours by the hourly cost. At £25 an hour, 160 hours cost £4,000. Use an all-in rate for a realistic figure.

What is cost per unit of work?
Total labour cost divided by the quantity completed, such as bricks, m³ excavated or m³ poured.

How is productivity per worker calculated?
Per worker-day it is quantity ÷ (workers × days). Per labour-hour it is quantity ÷ total labour hours.

Why are there separate modes for bricklaying, excavation and concrete?
The maths is the same. The modes change the labels so you enter the right unit of work.

Does this include materials and plant?
No. It covers labour time and cost only.

Related calculators

Once you know the labour, you need the quantities and the time. These tools help:

See all of them in our complete guide to free construction calculators.

Keep your site records in one place

Timesheets, progress photos, inspections and daily records help you check the real hours against the estimate. KaelSite helps UK site teams manage inspections, safety and reporting from one mobile-first app. Explore KaelSite features.

References