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billable-hours

A billable hours calculator tracks work time in fractional hours and computes the invoice amount. Useful for freelancers, lawyers, consultants — anyone billing by the hour. The ZTools Billable Hours tool offers two modes: a stopwatch (start / stop / pause) for live tracking, and a manual entry form for retroactive logging. Multiple rates per client / task, rounding rules (nearest 6 / 15 / 30 minutes), tax / discount, and CSV export of the time log.

Use cases​

Track hours for a client project​

Stopwatch starts when you begin work, pauses for breaks, stops at end of day. Tool sums total billable hours.

Calculate an invoice​

Total hours × rate = invoice amount. Tool handles multi-rate (different tasks at different rates) and tax.

Retroactive logging​

Forgot to start the timer? Manually enter time blocks (start, end). Tool computes total.

Compare planned vs actual​

Estimated 40 hours; actual 47. Tool shows over/under.

How it works​

  1. Add a task — Name, client, rate. Tool shows live timer or accepts manual time entry.
  2. Track time — Stopwatch with start / pause / stop. Multiple concurrent tasks if needed.
  3. Configure rounding — Lawyers often round to nearest 6 minutes (0.1 hour). Some round up to 15 minutes. Tool supports both.
  4. Export — CSV with task / client / hours / rate / amount. Plug into invoice software.

Examples​

Input: 3.5 hours @ $100/hour

Output: $350 (with rounding off).

Input: Same time, rounded up to nearest 15 min

Output: 3.75 hours × $100 = $375.

Input: Multi-rate: 2 h research @ $80, 1.5 h drafting @ $120

Output: $160 + $180 = $340.

Frequently asked questions​

Does it persist across sessions?

Tool uses localStorage (or @capacitor/preferences in mobile) — your data stays on the device. Closing the browser keeps logs; clearing browser data wipes them. Always export CSV regularly as backup.

How are partial hours rendered?

Decimal (3.5) by default. Toggle to show as HH:MM (3:30) for invoices that prefer that format.

Tax / discount handling?

Optional tax % applied to subtotal. Discounts are flat or percentage. Both shown in invoice export.

Multi-currency?

Pick currency per client. Tool tracks separately so cross-currency invoicing doesn't mix.

Privacy?

All client-side.

Tips​

  • Export CSV at the end of every week — protects against accidental browser data wipe.
  • For lawyer billing, round to 6-minute increments (0.1 hour). Most legal billing systems expect this.
  • For freelance work, track in 15-minute increments — simpler invoices.
  • Tag time by task type when possible — easier to identify which projects are most profitable.

Try it now​

The full billable-hours runs in your browser at https://ztools.zaions.com/billable-hours — no signup, no upload, no data leaves your device.

Open the tool ↗

Last updated: 2026-05-06 · Author: Ahsan Mahmood · Edit this page on GitHub