Chain Length Calculator · Links & Length

Chain Length Calculator

Work out the correct chain length in links from chainring, cog and chainstay

Drivetrain Diagram

For derailleur bikes use the largest chainring and largest cog. The derailleur takes up the slack on all other combinations.

Drivetrain

Chainring teeth (front)

Cog teeth (rear)

Chainstay length

Chainstay = centre of bottom bracket to centre of rear axle. Typical: road 405–420 mm · MTB 425–450 mm · gravel 425–440 mm.

Bike Type

Drivetrain

Common gear ranges

Chain Length

🔗 Standard Chain

Recommended chain length

—

Links (exact)

—

Buy (even links)

—

Chain length

—

Chain length (cm)

—

Chainring

—

Cog

—

Chainstay (in)

—

Extra links

—

Calculation breakdown

Term	Value	Working	Subtotal

Always confirm on the bike before cutting. A chain that is one link too short can damage the derailleur; one link too long can cause poor shifting.

\n';var escaped = toolHtml .replace(/&/g, '&') .replace(//g, '>') .replace(/"/g, '"');embedCodeTextarea.value = ''; }window.toggleEmbedPanel = function () { if (embedPanel.style.display === 'none' || embedPanel.style.display === '') { generateEmbedCode(); embedPanel.style.display = 'block'; } else { embedPanel.style.display = 'none'; } };window.copyEmbedCode = function () { embedCodeTextarea.select(); if (navigator.clipboard) { navigator.clipboard.writeText(embedCodeTextarea.value).then(function () { alert('Embed code copied!'); }).catch(function () { alert('Press Ctrl+C'); }); } else { alert('Press Ctrl+C'); } };function bindAll() { [chainringInput, cogInput, chainstayInput, chainstayUnit, drivetrainType].forEach(function (el) { el.addEventListener('input', calculate); el.addEventListener('change', calculate); }); }if (document.readyState === 'loading') { document.addEventListener('DOMContentLoaded', function () { bindAll(); calculate(); }); } else { bindAll(); calculate(); } })();

Creator & Maintainer

Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.

Rate this Tool

User Ratings:

0 out of 5 stars (based on 0 reviews)

Excellent

Very good

Average

Poor

Terrible

A chain that’s one link short will snap a derailleur. One link long and the rear mech won’t take up the slack. Getting the count right before you cut saves a £30 chain and a walk home. This chain length calculator uses the Sheldon Brown formula, which has been the workshop standard for decades. It takes three measurements off your bike and returns the link count in seconds. Road, gravel, mountain, single-speed, and internal gear hub setups are all covered. Full suspension frames get a two-link cushion for chain growth through the travel. The math runs locally, so nothing gets uploaded.

How to Use the Chain Length Calculator

Count the teeth on your largest front chainring and enter the number.
Count the teeth on your largest rear cog and enter that too.
Measure your chainstay length. Centre of the bottom bracket to centre of the rear axle.
Pick the unit you measured in. Millimetres is the easiest to get right.
Choose your drivetrain type from the dropdown.
Read the recommended link count in the hero panel.
Check the breakdown table underneath to see how each term contributes to the total.

For a derailleur bike, always use the largest chainring and the largest cog. The derailleur handles the slack on every other combination.

How the Chain Length Calculator Formula Works

The Sheldon Brown formula drives the whole calculation.

Formula: Links = 4C + F/2 + R/2 + 2
Where C = chainstay in inches, F = chainring teeth, R = cog teeth

Chain pitch on a bicycle is half an inch, so chain length in inches equals links divided by two. A 116-link chain measures 58 inches end to end, or about 147 cm.

Chainstay converts to inches before the formula runs. Millimetres divide by 25.4. Centimetres divide by 2.54. The formula assumes a derailleur bike, so it includes the slack needed for the cage to move through its range.

Full suspension frames add two extra links because the chain grows as the rear triangle compresses. The tool adds that automatically when you pick “Full suspension” from the dropdown. Single-speed, fixed gear, and internal gear hub setups don’t get the extra, since their chain path is fixed.

Chains must have an even number of links to join properly. The calculator rounds the exact figure up to the nearest even number. If the exact total lands on 114.3, you buy 116 links. If it lands on 116.0, you buy 116. The rounding is always up, never down, so you never come up short.

Worked Example

A gravel bike with a 42-tooth chainring, a 42-tooth largest cog, and a 428 mm chainstay.

Chainstay in inches: 428 ÷ 25.4 = 16.85 in
Term A (4C): 4 × 16.85 = 67.40
Term B (F/2): 42 ÷ 2 = 21.00
Term C (R/2): 42 ÷ 2 = 21.00
Constant: 2.00

Exact total: 67.40 + 21.00 + 21.00 + 2 = 111.40 links

Rounded up to even: 112 links
Chain length: 112 ÷ 2 = 56.00 inches, or 142.24 cm

The badge reads “Standard Chain” because 112 links falls in the 96-to-115 band.

That 112-link count fits most gravel setups with a 1× drivetrain. If you’re swapping to a smaller cassette later, you’ll probably need 114 or 116. Buy 116 and cut down to fit. Cutting up isn’t an option.

Frequently Asked Questions

How do you calculate chain length?

Use the Sheldon Brown formula: links = 4C + F/2 + R/2 + 2. C is chainstay length in inches, F is the largest chainring tooth count, and R is the largest cog tooth count. Round up to the nearest even number.

How many links does my bike chain need?

It depends on chainstay length and your largest chainring and cog. Road bikes typically need 108 to 114 links. Gravel and mountain bikes need 112 to 118. Single-speed setups run 96 to 104. The calculator gives you the exact number for your setup.

What is the Sheldon Brown formula for chain length?

L (inches) = 2C + F/4 + R/4 + 1, where C is chainstay in inches, F is chainring teeth, and R is cog teeth. Multiply by two to get links. It’s the standard formula used in bike workshops and matches manufacturer recommendations within one link.

How do I measure chainstay length?

Measure from the centre of the bottom bracket spindle to the centre of the rear axle. Use millimetres for the cleanest result. Road bikes sit at 405 to 420 mm. Gravel is 425 to 440 mm. Mountain bikes go up to 450 mm. Your frame’s geometry chart lists the exact figure.

How long is a 116-link chain?

A 116-link chain measures 58 inches, or about 147.3 cm. Bicycle chain pitch is half an inch, so chain length in inches equals links divided by two. Most 11-speed and 12-speed chains ship at 116 or 114 links.

Why do chains need an even number of links?

Inner and outer plates alternate along the chain. To close the loop, one end must be inner and the other outer. An odd number leaves two of the same type facing each other, which can’t be joined without a special half-link. The calculator always rounds up to the nearest even number.

Does chain length matter for a single-speed bike?

Yes, but there’s no derailleur to take up slack, so the chain has to be exact. Single-speed and fixed-gear setups often use a half-link or an eccentric bottom bracket to fine-tune tension. The formula still works, but you might need to adjust the rear wheel position in the dropouts.

Can I use a chain that’s one link too long?

One link too long is usually fine on a derailleur bike, but the chain may slap the chainstay in small gears and the derailleur cage may not tension properly. On a single-speed or internal gear hub, one link changes the wheel position by half an inch. For a derailleur bike, cut to the calculated length. Don’t leave slack you don’t need.

How much does chain length change if I swap cassettes?

Going from an 11-32 to an 11-34 cassette adds one link to the exact total. Since chains round up to even, the recommended count sometimes stays the same and sometimes goes up by two. Recalculate every time you change cassette size.

What size chain for a full suspension mountain bike?

Use the same formula, then add two links. Full suspension frames lengthen the chain path as the rear triangle compresses through its travel. Without those two extra links, the chain can snap the derailleur hanger on a hard landing. The calculator adds the two links automatically when you select the full suspension option.

Chain Length Calculator

Relevant Tools

Cycling Heart Rate Zone Calculator

Bike Pace Calculator