About

Billing errors cost freelancers and consultancies between 5% and 15% of annual revenue. The root cause is almost always imprecise time tracking or inconsistent rate application across tasks. This calculator computes total billable amounts from individual task entries, each with its own hourly rate r and logged duration t, then applies tax and optional discounts to produce an auditable invoice summary. It accepts time in both decimal hours and HH:MM format, converting internally to avoid rounding drift.

The tool assumes a flat-rate billing model. It does not handle retainer-based or milestone billing. For blended-rate scenarios, enter each rate tier as a separate line item. Pro tip: courts and tax authorities favor itemized records over lump sums - always break projects into discrete tasks.

Formulas

Each line item produces a billable amount B from logged hours t and the applicable hourly rate r:

B = t × r

The subtotal S aggregates all n line items:

S = n∑i=1 t_i × r_i

An optional discount D is applied (flat amount or percentage of S). Tax T is then computed on the discounted subtotal:

T = (S − D) × taxRate100

The grand total G:

G = S − D + T

Where: t = hours worked (decimal or converted from HH:MM), r = hourly rate in selected currency, n = number of task entries, D = discount amount, taxRate = tax percentage. The effective hourly rate equals Gn∑i=1 t_i.

Reference Data

Professional Role	Typical Hourly Rate (USD)	Common Billing Increment	Annual Billable Target (hrs)
Junior Developer	$50 - 80	15 min	1,600
Senior Developer	$100 - 175	15 min	1,500
UX/UI Designer	$75 - 150	30 min	1,400
Graphic Designer	$45 - 100	15 min	1,500
Copywriter	$50 - 120	15 min	1,400
Management Consultant	$150 - 350	6 min	1,800
Attorney (Associate)	$200 - 450	6 min	1,900
Attorney (Partner)	$400 - 1,000	6 min	1,700
Accountant (CPA)	$100 - 250	15 min	1,600
Architect	$100 - 200	15 min	1,500
Marketing Strategist	$80 - 180	15 min	1,500
Data Analyst	$70 - 140	15 min	1,600
Project Manager	$90 - 175	15 min	1,700
IT Security Consultant	$150 - 300	15 min	1,600
Translator / Interpreter	$40 - 100	15 min	1,400
Video Editor	$50 - 120	30 min	1,400
Photographer	$75 - 250	60 min	1,200
Virtual Assistant	$15 - 40	15 min	1,800

Frequently Asked Questions

Both formats are accepted. Enter 1.5 for one and a half hours, or 1:30 for the same duration. The calculator converts HH:MM to decimal internally by dividing minutes by 60. Use whichever matches your time-tracking method to avoid manual conversion errors.

Many professions bill in increments (e.g., 6-minute or 15-minute blocks). This calculator uses exact time entries without automatic rounding. If your contract specifies increment billing, round each task's hours up to the nearest increment before entering. For example, 0.1 hr of work billed in 15-minute increments should be entered as 0.25 hr.

Tax is computed on the discounted subtotal: T = (S − D) × taxRate ÷ 100. This matches the standard accounting practice in most jurisdictions. If your locale requires tax on the pre-discount amount, set the discount to zero and adjust your invoice manually.

Yes. Each line item has its own rate field. This supports blended-rate projects where, for example, design work bills at $120/hr while project management bills at $90/hr. The summary computes an effective blended rate across all entries.

The effective rate equals the grand total (after tax and discount) divided by total hours worked. It answers the question: "What did I actually earn per hour on this project?" If the effective rate is significantly lower than your target rate, it may indicate scope creep or under-billed administrative tasks.

You can select from several common currencies (USD, EUR, GBP, JPY, CAD, AUD, CHF, INR). The symbol is applied for display formatting only. No currency conversion is performed. All rates and amounts must be in the same currency.