Anchor Holding Power Calculator

Work out anchor holding power instantly with clear inputs, formula shown and shareable results.

About Anchor Holding Power Calculator

Anchor holding power is the anchor mass multiplied by a type-dependent holding factor, then reduced if the scope is short. Scope matters because holding depends on the pull being horizontal at the shank; a short scope lifts the shank and the anchor breaks out at a fraction of its rated hold.

Formula

Anchor holding

holding = anchor mass x holding factor x scope factor; safety factor = holding / expected load

Worked example

With the default values below, Anchor Holding Power Calculator returns Holding power of 3,530. Change any input above and every figure here is recalculated in your browser.

Inputs used

Anchor weight: 45 kg
Holding power factor: 8 x
Scope (chain length to depth ratio): 5 x
Expected wind and current load: 2,600 N

Results

Holding power: 3,530 N
Safety factor against the load: 1.358
Holding power: 360 kgf
Assessment: Marginal - acceptable only in settled conditions

Step by step

1Values used
2Anchor holding
3Holding power= 3,530 N
4Safety factor against the load= 1.358
5Holding power= 360 kgf
6Assessment= Marginal - acceptable only in settled conditions

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Marine results are planning estimates only. Verify against the vessel's approved stability booklet, loading manual, class society rules and applicable maritime regulations before loading or sailing.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Marine results are planning estimates only. Verify against the vessel's approved stability booklet, loading manual, class society rules and applicable maritime regulations before loading or sailing.

Frequently Asked Questions

What holding factor should I use?

Roughly 4-6 for traditional fisherman types, 8-12 for modern high-holding-power designs in good sand or mud, and far less in weed, rock or soft silt.

Why is 5:1 scope the usual minimum?

At 5:1 the catenary keeps the pull near horizontal in moderate conditions. In heavy weather 7:1 or 10:1 is recommended.