Castlecrag vs Seaforth: true annual running costs compared (2026)
Last updated July 2026 · council rates current NSW schedules, ATO 88c/km, Opal & Translink fares, AER electricity benchmarks
Castlecrag (Willoughby rates (OLG) and Seaforth (Northern Beaches rates (OLG) attract comparison from buyers considering suburbs across different council areas at similar distances from Sydney CBD (7.8 km and 8.6 km).
Castlecrag runs $640 a year cheaper than Seaforth, driven mostly by council rates. Over 10 years at 3% growth that gap compounds to about $7,337.
Over 10 years these two cost about the same to run. The difference here isn't money — it's location, schools and lifestyle.
Get the free report: 10-year costs, flood & fire risk, crime, schools and overall verdict →Castlecrag
Seaforth
Annual cost breakdown
| Category | Castlecrag | Seaforth | Difference |
|---|---|---|---|
| Council rates | $1,341 | $1,766 | -$425 |
| Water & sewerage | $1,548 | $1,548 | - |
| Commute (driving) | $2,379 | $2,594 | -$215 |
| Commute (public transport) | $1,920 | $1,920 | - |
| Home insurance | $2,150 | $2,150 | - |
| Body corporate (unit) | $2,600 | $2,600 | - |
| Total (driving) | $7,418 | $8,058 | -$640 |
| Total (public transport) | $6,959 | $7,384 | -$425 |
Green = cheaper. Commute: ATO 88c/km, 220 working days. Insurance AI-estimated; actual premiums vary. Council rates: average residential rate (NSW, IPART-uplifted).
| Dwelling | Castlecrag | Seaforth | Difference |
|---|---|---|---|
| House | $2,148 | $2,148 | - |
| Unit | $1,716 | $1,716 | - |
Estimated from AER residential benchmarks for each suburb's climate zone at 2025 rates (QLD 30c/kWh, NSW 33c/kWh incl. supply charge; unit ≈ 75% of a house). Get the free report for a breakdown by your exact number of occupants.
Cost breakdown chart
Annual cost breakdown — Castlecrag vs Seaforth (2026-27)
What the numbers show
Castlecrag costs $640 less per year to run by car. Held over ten years at 3% annual cost growth, that gap compounds to $7,337 in favour of Castlecrag.
The biggest single gap is council rates at $425 per year.
On public transport the gap is $425 per year, $6,959 from Castlecrag versus $7,384 from Seaforth.
10-year cumulative cost projection
| Year | Castlecrag cumulative | Seaforth cumulative | Difference |
|---|---|---|---|
| Year 1 | $7,418 | $8,058 | $640 |
| Year 3 | $22,928 | $24,906 | $1,978 |
| Year 5 | $39,383 | $42,781 | $3,398 |
| Year 10 | $85,039 | $92,376 | $7,337 |
Assumes 3% annual cost growth. Excludes purchase price, mortgage, and personal expenses.
Frequently asked questions
Is Castlecrag or Seaforth cheaper to live in?
Castlecrag is cheaper to run by car at $7,418 per year versus $8,058 for Seaforth, a difference of $640 annually. Figures cover council rates, water, commute (ATO 88c/km), and home insurance. Source: SuburbCost 2026 data.
What are council rates in Castlecrag and Seaforth?
Annual council rates for a house are $1,341 in Castlecrag (Willoughby rates (OLG) and $1,766 in Seaforth (Northern Beaches rates (OLG). Water and sewerage adds $1,548 in Castlecrag and $1,548 in Seaforth. Both figures are the average residential rate reported to the Office of Local Government, uplifted by each council's IPART rate peg.
How does the commute cost compare between Castlecrag and Seaforth?
Annual driving commute costs are $2,379 from Castlecrag and $2,594 from Seaforth to Sydney CBD (ATO 88c/km). Public transport costs $1,920 from Castlecrag and $1,920 from Seaforth.
What is the 10-year cost difference between Castlecrag and Seaforth?
At 3% annual cost growth, Castlecrag costs a cumulative $85,039 and Seaforth costs $92,376 over 10 years by car. The cumulative difference is $7,337 in favour of Castlecrag. Excludes purchase price, mortgage, and personal expenses.
Which of Castlecrag and Seaforth is best to actually live in?
You've got the costs. Get the free personalised report for the rest: a clear verdict on which suburb wins, the full flood, fire and crime risk profile, nearest schools, estimated electricity cost by number of occupants, and your own loan or rent stress-tested over 10 years. No spam.
Related comparisons
Sources: Willoughby rates (OLG and Northern Beaches rates (OLG rate data, water utility pricing (QLD: Queensland Urban Utilities / Unitywater; NSW: Sydney Water / Hunter Water), ATO 88c/km, and SuburbCost AI insurance estimates. Data updated July 2026.