Ballast to move the CG
How much ballast at a chosen arm brings the to a target, and the new total weight.
Planning and education aid. Not for primary navigation. Full disclaimer
Experimental: not yet fully verified. How results are checked
Add 40.1 lb of ballast; the airplane then weighs 2,290.1 lb.
- New total weight
Provenance
- Computed by
- aviation.loading.ballast 1.0.0, core 0.1.0
- Model
- Ballast = total weight × (target CG − CG now) ÷ (ballast arm − target CG), from taking moments about the datum (FAA-H-8083-1B, chapter 2)
- Accuracy
- Exact for the entered weights and arms. Check the new total weight against the maximum, and secure ballast as the aircraft's data requires
- Notes
- 1 shown with the answer
- Cites
- Federal Aviation Administration, Aircraft Weight and Balance Handbook, FAA-H-8083-1B
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: Ballast = total weight × (target CG − CG now) ÷ (ballast arm − target CG), from taking moments about the datum (FAA-H-8083-1B, chapter 2)
Show your work
CG change needed
target CG − CG now83 − 84.3= -1.3 inBallast
total weight × (target − CG) ÷ (arm − target)2,250 × (83 − 84.3) ÷ (10 − 83)= 40.1 lb
The same steps an agent gets from the MCP server with explain: true.
Accuracy: Exact for the entered weights and arms. Check the new total weight against the maximum, and secure ballast as the aircraft's data requires
Worked example: 2,250 lb at 84.3 in, to 83.0 in with ballast at 10 in. Source: Worked from moments: 2,250 × (83.0 − 84.3) ÷ (10 − 83.0) = 40.1 lb. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- Ballast arm
- 10 in
- CG now
- 84.3 in
- Target CG
- 83.0 in
- Total weight
- 2250 lb
You get
- Ballast weight
- 40.1 lb
- New total weight
- 2,290.1 lb
Review: Not yet independently reviewed by a flight instructor (CFI).
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 5 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Aircraft Weight and Balance Handbook, FAA-H-8083-1B, Federal Aviation Administration, FAA-H-8083-1B. Chapter 2 (shifting the CG: weight moved ÷ total weight = CG change ÷ distance moved; adding or removing weight and ballast).
Terms
- CG: center of gravity
- The point where an aircraft's weight acts. It must stay inside the envelope in the POH for safe control. Source: Aircraft Weight and Balance Handbook
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.
CG — center of gravity
The point where an aircraft's weight acts. It must stay inside the envelope in the POH for safe control.
Source: Aircraft Weight and Balance Handbook