A first-pass mass budget for payload integration and configuration trade studies.
Start here
- Enter maximum take-off mass and the aircraft, energy-system and fixed-equipment masses.
- Add your proposed payload and contingency percentage, then choose Calculate.
- Read the payload allowance and remaining mass margin.
How to read the results
A positive mass margin does not establish physical fit, CG or electrical compatibility; use those calculators for the corresponding checks.
Optional aircraft profile: Manual values
Payload and MTOW Budget Calculator
Planning output only. Verify assumptions and results against authoritative data, manufacturer information, approved procedures, test evidence and competent engineering or regulatory review before use.
Calculation basis
Available payload equals MTOW minus empty mass, energy mass, fixed equipment/integration mass and the entered MTOW contingency. Payload margin compares that allowance with the proposed payload.
Limitations and verification
- A positive mass margin does not demonstrate acceptable centre of gravity, structural loads, handling, endurance or regulatory compliance.
- Use the released aircraft definition and measured configuration masses.
- Account for mounts, cables, connectors, cooling, antennas and retained installation hardware.
Version and review status
Formula set: v1.2
Staging review date: 17 August 2026
Status: Staging beta pending user acceptance and cross-browser checks.
Using this calculator
A first-pass mass budget for payload integration and configuration trade studies.
Inputs and units
| Input | Unit or format |
|---|---|
| Maximum take-off mass | kg |
| Platform empty mass | kg |
| Battery or fuel mass | kg |
| Fixed equipment and integration mass | kg |
| Proposed payload mass | kg |
| Mass contingency | % MTOW |
Model and formula
Contingency mass = MTOW × contingency / 100. Available payload = MTOW − empty mass − energy mass − fixed mass − contingency mass. Payload margin = available payload − proposed payload.
Worked example
With MTOW 25 kg, empty mass 12 kg, energy mass 6 kg, fixed equipment 1 kg, proposed payload 4 kg and contingency 5%, the reserved mass is 1.25 kg. Available payload is 4.75 kg and the payload margin after contingency is 0.75 kg. The proposed take-off mass is 23 kg, giving a direct MTOW margin of 2 kg.
Interpreting the result
Keep direct MTOW margin separate from the margin after contingency. The latter is the unallocated allowance after retaining the chosen reserve. The example passes the mass check only; it says nothing about airworthiness or payload suitability.
Limits and verification
- A positive mass margin does not demonstrate acceptable centre of gravity, structural loads, handling, endurance or regulatory compliance.
- Use the released aircraft definition and measured configuration masses.
- Account for mounts, cables, connectors, cooling, antennas and retained installation hardware.
Worked examples checked against the calculator source on . These are reproducible calculation checks, not aircraft trials, site measurements or operational approval. Existing formula versions and technical review status remain as stated above.