Retainer invoice calculator

How the monthly retainer is calculated

monthly retainer = included monthly hours × hourly rate

A simple monthly retainer can be calculated by multiplying the agreed monthly capacity by the hourly rate. The result becomes a single fixed-fee invoice line, not an hourly line, because the commercial agreement is a fixed recurring fee rather than a record of hours actually worked.

20 hours/month at €100/hour

20 hours/month × €100.00/hour = €2,000.00 monthly retainer. The final fee should reflect the actual agreement with your client, not only this baseline calculation.

A retainer becomes one fixed-fee invoice line

The calculated retainer becomes a single invoice line: the description you entered (or "Monthly retainer"), quantity 1, and the calculated amount as the rate. It is a fixed-fee line, not an hourly line — the invoice does not need to show the included hours or hourly rate used to plan it.

Check these before invoicing a retainer

• A retainer is not the same as hours already worked — it is a fixed fee for agreed recurring capacity, calculated here as a planning baseline.
• A retainer is not a deposit — a deposit is an upfront payment toward a specific project total, not a recurring fee.
• This tool does not manage recurring or automatic billing — it calculates the fee for one billing period, which you invoice yourself each period.
• Work beyond the included monthly hours may need a separate agreement or invoice line — clarify overage handling with your client before invoicing it.
• Unused included hours are not automatically carried over or refunded unless your agreement says so.
• This calculator does not determine VAT or tax treatment — use the VAT calculator or a tax adviser for that.