OPEX Budget Calculator

Build a clean operating expense (OPEX) budget from monthly line items, add a contingency, and see totals for your chosen horizon—plus optional benchmarks vs revenue and per employee.

Annual budget view (most common)
$
%
$
$
$
$
$

Results

  • Base monthly OPEX $
  • Contingency (monthly) $
  • Total monthly OPEX $
  • Total budget (horizon) $
  • Annualized OPEX (run-rate) $
  • OPEX as % of revenue %
  • OPEX per employee (monthly) $

What is OPEX Budget Calculator? (or a better fitting intro idea)

An OPEX budget is a forward plan for the recurring operating expenses needed to run the business (typically SG&A and R&D), excluding capital expenditures (CAPEX).

It matters because OPEX is the biggest lever on operating profit/EBITDA, burn rate and cash runway, hiring pace (headcount planning), and variance analysis against actuals.

Formula







Example

Assume a 3-month horizon, 25 employees, and a 5% contingency:

  • Payroll (monthly): $150,000
  • Facilities (monthly): $8,000
  • Software & tools (monthly): $4,000
  • Marketing & sales (monthly): $12,000
  • Other OPEX (monthly): $3,000

1) Base monthly OPEX:

2) Contingency (monthly):

3) Total monthly OPEX:

4) Total budget (3 months):

5) Annualized OPEX (run-rate):

6) OPEX per employee (monthly):

How to Use the OPEX Budget Calculator

Pick a budget horizon, enter your monthly operating expense drivers, and optionally add revenue/headcount to benchmark efficiency. The results update automatically as you change inputs.

  1. Choose your budget horizon

    • Select 3 months, 6 months, or 12 months depending on whether you’re planning quarterly, semi-annual, or annual.

  2. Enter your monthly OPEX drivers

    • Fill in the monthly amounts for Payroll, Facilities, Software & tools, Marketing & sales, and Other OPEX.

  3. Add a contingency buffer (optional but recommended)

    • Set the contingency % to automatically add a buffer to your base OPEX:
    • Base monthly OPEX = Payroll + Facilities + Software & tools + Marketing & sales + Other OPEX
    • Monthly contingency = Base monthly OPEX × (Contingency percentage ÷ 100)
    • Total monthly OPEX = Base monthly OPEX + Monthly contingency

  4. Add benchmarks (optional): revenue and headcount

    • Enter Annual revenue to calculate OPEX-to-revenue, and Average headcount to calculate OPEX per employee:
    • OPEX-to-Revenue ratio = (Total monthly OPEX × 12) ÷ Annual revenue
    • OPEX per employee (monthly) = Total monthly OPEX ÷ Average headcount

  5. Read the results and use them for planning

      • Review Base monthly OPEX, Contingency, Total monthly OPEX, Total budget (horizon), and Annualized OPEX (run-rate).

    - Use Share / Embed if you want to send the scenario to teammates or drop it into a doc.

Frequently Asked Questions

Methodology & Sources

Bibliography

  1. (2019). 7.2 Prepare Operating Budgets (Principles of Accounting, Volume 2: Managerial Accounting) — OpenStax (Rice University)
    Accessed 2025-12-17
  2. (2019). Operating Budget Expenses — Cornell University
    Accessed 2025-12-17
  3. (2021). How to Prepare an Operating Budget (Budget Workshop Presentation, Rev 03-2021) — University Budget Office, University of Maryland (finance.umd.edu)
    Accessed 2025-12-17

Other Calculators in Operations & Workforce Metrics

Operations & Workforce Metrics

Budget vs Actual Variance Calculator
Operations & Workforce Metrics

Cash Runway & Burn Rate Calculator
Operations & Workforce Metrics

Headcount Planning Calculator