Some businesses are unable to give standard prices for goods and services. This may be because the skills, time and materials required for each job vary depending on different customers' needs.
A quote (quotation) is a fixed price offer that can't be changed once accepted by the customer. This holds true even if you have to carry out much more work than you expected.
An estimate is an educated guess at what a job may cost - but it isn't binding. To take account of possible unforeseen developments, you should provide several estimates based on various circumstances, including the worst-case scenario. This will prevent your customer from being surprised by the costs.
If you provide goods or services to other businesses or the public sector, you may have to compete for contracts by submitting a tender. Although value for money can be an important component of many tenders, the way you price your bid can also make the difference between winning or losing business. As with quotations, you're committed to the price you submit in a tender if it is accepted.
You need to know your fixed and variable costs including the cost-per-hour of manual labour and the cost of the materials you'll require. Your quote, estimate or tender is then calculated according to what you think the job will involve.