Oar Size Calculator
Measure the distance between the oarlocks across the boat. The calculator applies the traditional 7:25 rule to give the oar length, the nearest stock size, the inboard and outboard lengths and the handle overlap.
- Oar length
- Inboard
- Stock size
Measure between the centres of the oarlocks.
Oar length comes from the span between the oarlocks. Take half the span, add 2 in, then multiply by 25 and divide by 7. A boat 48 in across the oarlocks needs oars about 93 in long, so 7.5 ft oars. About 7/25 of each oar sits inboard of the oarlock.
Oar length chart
7:25 rule. Search for a span.
| Span (in) | Oar (in) | Stock size (ft) | Inboard (in) |
|---|---|---|---|
| 36 | 71.4 | 6 | 20 |
| 40 | 78.6 | 6.5 | 22 |
| 44 | 85.7 | 7 | 24 |
| 48 | 92.9 | 7.5 | 26 |
| 52 | 100 | 8.5 | 28 |
| 56 | 107.1 | 9 | 30 |
| 60 | 114.3 | 9.5 | 32 |
| 66 | 125 | 10.5 | 35 |
Rounded to half feet.
Span and oar
7:25 rule. Slide the span.
The boat is drawn from above with both oars.
How to size oars
Span to oars. Step through it.
Measure
Oarlock span.
Leather the oars where they sit in the oarlocks to protect them and stop squeaks.
Rowboat, dinghy or sculling oars
Oar types. Compare them.
Wide hull.
Narrow.
Racing.
Racing sculls use carbon oars of fixed length set by the rigger.
Before you buy
Oar checks. Tick each item.
Tick each item as you go.
Buttons or collars stop the oars sliding out through the oarlocks.
What you get
Oar sizing. Each tile explains one result.
Inches.
Feet.
Length.
Length.
Handles.
Oars that are too short make you work hard for little speed.
Frequently Asked Questions
No question matches that search.
How long should my oars be?
Half the oarlock span plus two inches, times twenty-five divided by seven.
What size oars for a ten foot boat?
Usually about six and a half to seven feet, depending on the oarlock span.
What is the inboard length of an oar?
The part from the handle to the oarlock, about seven twenty-fifths of the length.
Should oar handles overlap?
Yes, by a few inches, with one hand passing above the other.
What are oar leathers?
Leather sleeves where the oar rests in the oarlock.
Are longer oars better?
Only to a point. Too long and the stroke feels heavy.
How do I measure oarlock span?
Measure straight across between the centres of the two oarlocks.
Pull a better stroke
Size the oars for your boat's span and every stroke is long, smooth and easy.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.