Archery arrow length: why it's draw length plus an offset, not a ratio
A new archer at our club assumed arrow length should scale as a percentage of draw length, like a lot of other sporting-goods sizing rules, and was surprised the actual rule of thumb is just a fixed inch or two added on
We write the way we argue on the bench: exact factor, one sharp trap, one worked example you can re-check.
A new archer at our club assumed arrow length should scale as a percentage of draw length, like a lot of other sporting-goods sizing rules, and was surprised the actual rule of thumb is just a fixed inch or two added on top.
The factor below is the one that ends the argument — write it once, then stop improvising mid-job.
The factor that settles arguments
This is the relationship our converters use. Screenshot it if you have to — just stop re-deriving it from a half-remembered blog post.
Recommended arrow length ≈ draw length + 1 to 2 inches (a rule-of-thumb offset, not a fixed ratio)
Write that line once at the top of your notes. Every later arithmetic step should point back to it instead of inventing a friendlier number mid-stream.
The mistake that keeps showing up
Calculating arrow length as a percentage or ratio of draw length instead of the simpler additive rule of thumb — this mix-up leads to arrows sized noticeably wrong for taller or shorter archers.
I still write the unit next to every intermediate value. It looks pedantic until it catches the one swap that would have shipped wrong.
- Write down the known value in draw length (in).
- Confirm the target unit is really recommended arrow length (in, +1.5in offset), not a similar-looking one.
- Apply the factor: Recommended arrow length ≈ draw length + 1 to 2 inches (a rule-of-thumb offset, not a fixed ratio).
- Round only at the end, to the precision your tool or spec supports.
Worked example
An archer's measured draw length is 28 inches, and they need a recommended starting arrow length.
A 28 inch draw length plus a typical 1.5 inch offset: 28 + 1.5 = 29.5 inches recommended arrow length.
That's about 29.5 inches — the relationship is additive, not a percentage or ratio of draw length.
Flip the factor once as a sanity check. If you do not land near the starting number, you mixed definitions or inverted the direction.
Quick reference table
| draw length (in) | Calculation | recommended arrow length (in, +1.5in offset) |
|---|---|---|
| 1 | 1 × — | — |
| 2 | 2 × — | — |
| 5 | 5 × — | — |
| 10 | 10 × — | — |
Use the table for speed once you trust the factor. Do not use it as a substitute for understanding which definition of the unit you are on.
Why the exact number matters
Arrows that are too short are a genuine safety hazard (risk of overdraw off the rest), while too long affects accuracy and spine performance — getting this rule of thumb right matters more than most sizing guides.
Precision is not about showing off decimals. It is about making sure the shopping list, the machine setting, and the acceptance check are all describing the same physical quantity.
Pocket recap
Add roughly 1 to 2 inches to draw length for a starting arrow length recommendation, then fine-tune with a bow shop's fitting — it's an offset, not a scaled ratio.
Keep the converter link nearby for the next time the same debate shows up in a group chat. Re-typing the factor from memory is how the wrong cousin of a unit sneaks back in.
Try the converters mentioned in this article
FAQ
What is the exact draw length (in) to recommended arrow length (in, +1.5in offset) factor here?+
Recommended arrow length ≈ draw length + 1 to 2 inches (a rule-of-thumb offset, not a fixed ratio)
Should I round partway through the calculation?+
No — carry full precision through the multiplication and round only the final answer, to the precision your tool, gauge, or spec actually supports.
What's the single biggest mistake people make with this conversion?+
Calculating arrow length as a percentage or ratio of draw length instead of the simpler additive rule of thumb — this mix-up leads to arrows sized noticeably wrong for taller or shorter archers.
This article was written by The Turbo Unit Converter engineering desk (Applied units & field metrology) and last reviewed on 2026-07-15 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.