How does this estimate forgotten work?

It uses your forgotten item count and assumes each missed item represents a modest amount of shipped billable work. The goal is to surface the likely order of magnitude, not produce accounting-grade precision.

Why include admin time in the leakage number?

Because invoice reconstruction, cleanup, and follow-up still consume billable capacity. Even when no work is forgotten, manual billing drags down revenue.

Is this only for hourly billing?

No. The hourly rate is just a simple way to convert lost time and missed work into revenue impact, even if you quote retainers or project fees.

Calculator

Underbilling and revenue leakage calculator

See how much money disappears when merged pull requests go unbilled and invoice prep still depends on memory, notes, or spreadsheets.

The hidden cost of manual billing is not just admin time. It is also the GitHub work that never makes it onto the invoice in the first place.

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Preparing interactive inputs

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Example: monthly billing from a busy GitHub repo

A consultant merges a healthy number of PRs each month, but still reconstructs invoices manually.

Parameters

Merged PRs22 / month

Forgotten items3 / month

Average billable rate$150/hr

Invoice prep time2.5 hours/month

Billing admin time4 hours/month

Results

Estimated revenue leakage

$1,763/month

Time you could recover

6.5 hours/month

Diffbill payback framing

Pays for itself about 88x over

Estimate monthly revenue lost to forgotten shipped work.

Quantify manual invoice prep and billing-admin time in dollars.

Compare the leak to Diffbill’s cost to frame payback clearly.

Common questions

Explore more

Explore more billing workflows and tools

Move from one-off calculations into the pages that explain the full GitHub-to-invoice workflow.

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Comparison

diffbill vs Harvest

Choose diffbill when your billing source of truth is shipped work in GitHub. Choose Harvest when your team still needs timesheets, hour approvals, and classic time-tracking workflows.

Comparison

diffbill vs ChatGPT

Choose diffbill when you invoice regularly and want a repeatable GitHub-to-Stripe workflow. Use manual ChatGPT prompting only if you create a handful of invoices per year and do not need consistency or audit trails.

Comparison

diffbill vs InvoBee

Choose diffbill when you bill from shipped code in GitHub and want PR-sourced line items without rebuilding the month from timers or notes. Choose InvoBee when you want a general-purpose freelancer suite with time tracking, expenses, and projects across any kind of work.

Use case

GitHub invoicing software for freelance developers

If you invoice clients based on shipped code, diffbill gives freelance developers a faster way to capture every piece of delivered work, explain its value in plain language, and send cleaner invoices.