Bow Length vs String Length: What to Measure First
Bow length is the bow’s AMO length. String length is shorter, and it must match the bow’s spec, not the limb tip-to-tip measure. On most recurves, expect a string about 3 to 4 inches shorter than AMO length. The wrong size can throw off brace height, hurt accuracy, and make the bow unsafe to shoot. This guide shows how to identify your bow’s length, read string specs, and decide whether you need a new string, a different length, or a brace-height correction.
This guide is part of our Bow measurements guide series.
| Decision factor | Bow Length | String Length | Winner |
|---|---|---|---|
| What it identifies | The bow’s AMO length reference | The ordered loop-to-loop string size for a recurve or longbow | Tie |
| Best use | Choosing the correct bow-size category | Ordering the correct replacement string | Tie |
| What affects fit | Bow model and AMO marking | Bow type, AMO length, brace height, and material choice | String Length |
| Risk of confusion | Low if you read the marking | High if you guess from bow length alone | Bow Length |
| Use in replacement decisions | Starts the lookup | Solves the order | String Length |
Bow length vs string length: what the terms mean
Bow length is the AMO length printed or implied for the bow. String length is the ordered size of the string, and for recurves and longbows it is usually several inches shorter than the bow’s AMO length. A 68-inch AMO recurve commonly uses a 64-inch AMO string, which is why the two numbers do not match.
AMO bow length
For recurve and longbow strings, AMO bow length refers to the bow length, not the string length. That matters because a 62-inch AMO bow is listed with a 58-59-inch string range, while a 68-inch AMO bow is listed with a 64-65-inch string range. The bow marking is the starting point, not the final answer.
AMO string length
AMO string length is the ordered size for recurve and longbow strings, measured loop-to-loop. That is the dimension sellers use when they label replacement strings for traditional bows. It is not the same convention used for compound bow strings.
Why a bowstring is usually shorter than the bow
A bowstring must create brace height when installed, so its measured length is shorter than the bow’s AMO length. A common rule of thumb is that string length is typically 3-4 inches shorter than bow AMO length. Brace height is part of that relationship, which is why the same marked bow can accept a small range of string lengths.
What you’ll need before you measure or replace a string
- The bow’s marked AMO length, if it is printed on the limb or riser
- A tape measure or ruler
- The manufacturer manual or model specs
- A bow stringer
- The old string, only if it is known to fit and is not obviously stretched or damaged
How do you tell if you need the bow length, the string length, or a brace-height fix?
Check the bow’s AMO marking first, then measure brace height next, and use the old string only if it was known good. If the bow length matches the model but brace height is off, the string may need twists rather than replacement. If the old string was unknown or suspect, do not trust it as the sizing reference.
Start with the bow marking
If the limb says 68 AMO, that is the bow length reference. For a recurve or longbow, that number points you toward a shorter string size, not a matching 68-inch string. If the bow has no markings, move to the manufacturer specs or model listing.
Then check brace height
Brace height is the distance from the grip to the string at rest. It changes when string length changes, and the calculator says recurve string length depends on brace height. Typical recurve brace height is given as 8-9 inches, but the bow’s own spec should control.
Use the old string only if it was known good
If the old string is frayed, stretched, or unknown, it can lead you to the wrong order. Measure loop-to-loop only when the string was previously fitting the bow correctly. A string can also be slightly adjusted with twists, so length alone does not tell the whole story.
Measure the right thing in the right order
- Identify whether the bow is a recurve, longbow, or compound.
- Read the marked AMO bow length on the bow or in the model specs.
- Measure the existing string from inside loop to inside loop if it is trusted.
- Measure brace height and compare it to the manufacturer spec.
- Order a new string if the old one is wrong, or add twists if brace height is only slightly off.
Recurve and longbow strings
Recurve and longbow strings should be measured from the inside of one loop to the inside of the other loop. For these bows, the string is usually shorter than the bow, and the final fit depends on brace height after installation. Use a bow stringer for safe stringing and unstringing.
Compound bow strings
Compound bow strings are measured differently. They are measured from serving end to serving end, not including loops. Compound string and cable sizing should follow the manufacturer or model specs, because axle-to-axle length and serving points matter more than the traditional AMO recurve method.
How do you choose the right bowstring length for a recurve or longbow?
Choose by bow type, AMO bow length, and brace height, not by the limb-tip span alone. A 68-inch AMO recurve commonly uses a 64-inch AMO string, and a 62-inch AMO bow is listed with a 58-59-inch string range. Material choice also matters, because different string materials are not interchangeable on every bow.
Common AMO size examples
For quick reference, a 68-inch AMO bow is often paired with a 64-65-inch string range. A 62-inch AMO bow is listed with a 58-59-inch string range. A 70-inch bow generally follows the same pattern: the string is shorter than the bow, with the exact size tied to brace height and bow design.
How material choice affects fit and feel
Dacron B-50 is commonly used on traditional bows and older limbs that need a more forgiving string material. Fast Flight and BCY 8125 are higher-performance materials, but only if the bow is rated for them. The wrong material can be unsafe even when the length is correct.
When a twist adjustment is acceptable
If the string is close but brace height sits a little low or high, adding or removing twists can move the brace height into spec. That is a correction step, not a substitute for a clearly wrong string size. A too-short string should never be used.
Proof table: order the right string the first time
| Bow type | Marked AMO length | Current brace height | Old-string status | Next action | Likely string size direction |
|---|---|---|---|---|---|
| Recurve | 68 inches | 8-9 inches | Known good, loop-to-loop known | Match the old string to the same AMO size and fine-tune with twists | 64-inch AMO string, then adjust if needed |
| Recurve | 62 inches | Below spec | Old string missing | Use model specs and order from the AMO length, then verify brace height after installation | 58-59-inch AMO string range |
| Longbow | 66 inches | Within spec | Old string worn but measured | Replace with the same measured loop-to-loop length if the fit was correct | Usually several inches shorter than bow AMO length |
| Recurve or longbow | Unknown | Unknown | No string and no manual | Find the model specs before ordering; do not guess from limb tip-to-tip length | Use AMO length, then confirm by brace height |
| Compound | Axle-to-axle listed by model | Specified by model | Old string missing | Order by manufacturer string and cable spec, not AMO recurve rules | Use serving-end measurements only |
Common mistakes that lead to the wrong string
Most errors come from treating bow length and string length as interchangeable. Another common mistake is reading a low brace height as proof that the bow needs a shorter bow length, when it may only need a twist correction or a new string of the correct AMO size. Skipping material compatibility can also create a bad fit.
Confusing low brace height with the wrong bow length
A low brace height does not automatically mean the bow is the wrong size. It may mean the installed string is too long, the string has stretched, or the bow needs more twists to come back into spec. Check the bow’s AMO marking before changing the length category.
Ordering by marked bow length alone
Marked bow length is the reference, not the string order number. A 68-inch AMO recurve often needs a 64-inch string, so ordering a 68-inch string would be wrong. If the bow has no manual and the old string is missing, the model spec is the next best source.
Ignoring material compatibility
Dacron B-50, Fast Flight, and BCY 8125 are not universal choices. Some older limbs should stay on Dacron, while many modern recurves can use faster materials if the maker approves them. Using the wrong material can cause wear or limb stress even if the length is right.
Skipping the bow stringer
A bow stringer reduces limb-twist risk during stringing and unstringing. That matters most when the correct size is still being confirmed and multiple installations may be needed. A stringer is part of safe replacement, not an optional extra.
Why is my bowstring shorter than my bow?
That is usually correct for recurves and longbows. The string must create brace height, and AMO bow length is not the same as AMO string length. If the string is only slightly shorter than the bow and brace height lands in spec, the fit may be right.
Say your 68-inch AMO recurve gets a 64-inch AMO string and the brace height lands at 8.5 inches. That is normal. Suppose the same bow ends up with a visibly slack string and a brace height below spec; then the string length or twist count needs attention.
What happens if a bowstring is too short or too long?
A too-short string raises brace height too much, can increase stress, and should never be used. A too-long string can leave brace height too low, affect clearance, and create a noisy shot. Either problem can affect tuning, so the fix is to match the string to the bow and then verify brace height.
If that didn’t work, try this next
- Remove the string and compare the measured loop-to-loop length with the bow’s AMO size.
- Check whether the string material is approved for the bow model.
- Install the replacement with a bow stringer and recheck brace height.
- Add or remove twists only if the length is close and the bow maker allows that adjustment.
Prevention: keep the string’s loop-to-loop length written on the tag or in a note with the bow, along with the brace height that worked best.
Verdict: Bow Length or String Length?
Choose Bow Length if you are checking the bow’s marked AMO length first to identify the bow-size category, like reading a 68 AMO recurve or finding the model/spec listing when the bow has no markings.
Choose String Length if you are ordering a replacement loop-to-loop string for a recurve or longbow, especially when you need the usual 58-59-inch or 64-65-inch AMO string range and want to confirm brace height after installation.
Frequently asked questions
What is the difference between bow length and string length?
Bow length is the AMO length of the bow itself. String length is the ordered loop-to-loop size for a recurve or longbow, and it is usually several inches shorter than the bow. The bow length tells you the category; the string length tells you what to buy.
How do I measure bow string length correctly?
Measure a recurve or longbow string from the inside of one loop to the inside of the other loop. Do not include stretched loops or servings. If the bow is a compound, use the manufacturer’s serving-end measurement instead, because the traditional loop-to-loop rule does not apply.
Is bow string length the same as bow length?
No. A 68-inch AMO recurve commonly uses a 64-inch AMO string, and a 62-inch AMO bow is listed with a 58-59-inch string range. The string is shorter by design so the bow reaches the right brace height when strung.
How do I choose the right string length for my bow?
Start with the bow’s AMO length, then check the model’s brace-height spec. If the old string was known good, match its loop-to-loop length and verify brace height after installation. If the old string is missing, use the bow type and AMO marking rather than guessing from tip-to-tip length.
How do I measure a longbow string length?
Measure from the inside of one loop to the inside of the other loop, just like a recurve string. Then compare that size with the longbow’s AMO length and the brace-height target in the model spec. Longbow designs can vary, so the bow’s approved range still matters.
How do I measure a recurve bow string without guessing?
Read the AMO length on the bow, check the manufacturer spec for brace height, and measure the old string only if it was already fitting correctly. A 68-inch AMO recurve often points to a 64-inch string, but the final confirmation is the brace height after stringing with a bow stringer.
length vs lenght
The correct search term is “length,” not “lenght.” If the spelling is the problem, the fix is simple: search by the bow’s AMO length and the string’s loop-to-loop size. Spelling does not change the measurement rule, but it can keep the right specs from showing up.
