Do you have to loosen the bar nuts to tension a chainsaw chain?

On a saw with a traditional side cover and bar nuts, yes — the bar has to be free to slide forward or the tensioner is just fighting clamped metal, and forcing it strips the adjuster pin. Loosen the nuts about half a turn so the bar can move but is not flopping. Tool-free systems on many modern saws combine the clamping knob and the tensioning dial, and there you loosen the outer knob first, then turn the dial.

Why do you lift the nose of the bar when tensioning?

Lifting the bar nose seats the bar against the top of its adjustment slot and takes the sag out of the top run of the chain, so the tension you set is the tension you get. If you tighten the bar nuts with the nose hanging down, the bar drops as you cut and the chain effectively goes slack. Hold the nose up with your free hand or rest it on a block, tension the chain, then tighten the nuts while the nose is still raised.

Which way do you turn a chainsaw tensioning screw?

Clockwise tightens and counter-clockwise loosens on virtually every saw. The screw sits either on the side of the saw behind the bar or on the front edge of the housing near the bar mount. Turn it in small increments — a quarter turn moves the chain more than most people expect — and check the tension after each adjustment rather than winding it in and hoping.

How do you tension a chainsaw chain that keeps coming loose?

First check whether the chain has simply worn out: if the tensioner has run to the end of its travel and the chain still sags, the chain has stretched past its service life and needs replacing. If there is travel left, the usual causes are bar nuts not fully tightened after adjustment, a worn adjuster pin that is slipping in the bar slot, or a bar with elongated mounting slots. Inspect the bar rails for uneven wear at the same time.

Should you tension a chainsaw chain hot or cold?

Set it cold and re-check it warm. A chain expands as it heats, so a chain tensioned on a hot saw will contract as it cools and can bind hard enough to seize on the bar. If you have been cutting and the chain feels loose, stop the saw, let the chain cool enough to touch safely, then adjust. Never leave a saw in storage with a chain tensioned while hot.

How to Tension a Chainsaw Chain (Step by Step)

Written & researched by Priya Anand DIY & Tools Editor

Updated October 2026

Over-the-shoulder view of a person trimming a green hedge with shears, cut leaves falling, in warm late-afternoon light

Affiliate Disclosure

Some links on this page are affiliate links. As an Amazon Associate, we earn from qualifying purchases — at no extra cost to you. We do not buy, test, or physically handle the products we cover; our rankings come from aggregated owner reviews, ratings and expert consensus. Commissions never change our verdicts. How we rank · full disclosure.

To tension a chainsaw chain: stop the saw and let the chain cool, loosen the bar nuts or side-cover knob about half a turn, lift the bar nose so it seats at the top of its slot, turn the tensioning screw clockwise in small steps until the chain sits flush against the underside of the bar with no sag, then tighten the bar nuts while still holding the nose up. Check by pulling the chain away at the bar midpoint — the drive links must stay in the groove — and by rotating the chain by hand, which should take steady effort. Two minutes, and it is the maintenance job that most affects how a saw cuts.

What you need

The scrench supplied with the saw — a combined screwdriver and socket wrench — or a screwdriver plus the correct nut size.
Cut-resistant gloves. You will be handling a sharp chain directly.
A stable surface — a bench, a tailgate or a flat stump. Not your knee.
Nothing at all if the saw has a tool-free tensioner, which is now common on battery saws.

Three-quarter view of a person trimming a green hedge with shears, cut leaves falling, in soft early-morning light

Tensioning a chain with bar nuts

Make the saw safe. Stop the engine, remove the battery, or unplug the cord. On a gas saw, let the chain cool until you can rest a gloved hand on it comfortably — a hot chain gives a false tension reading.
Release the chain brake. With the brake engaged the chain cannot rotate, and you need to be able to turn it by hand to check the result. Pull the front hand guard back toward the front handle until it clicks.
Loosen the bar nuts about half a turn. Enough that the bar can slide in its slot, not so much that the side cover is loose. On a tool-free system, loosen the outer clamping knob instead.
Lift the bar nose. Hold the tip up with your free hand, or rest it on a block, so the bar seats at the top of its adjustment slot. Keep it up for the rest of the procedure — this is the step people skip and the reason chains go slack after adjustment.
Turn the tensioning screw clockwise in quarter turns. The screw is on the side of the saw behind the bar, or on the front face of the housing near the bar mount, depending on the model. Watch the sag on the underside of the bar disappear.
Stop when the chain sits flush. Correct tension is snug against the underside of the bar with no visible sag, while the chain can still be pulled slightly away with the drive links staying seated in the groove.
Tighten the bar nuts fully while the nose is still lifted. Snug, not overtightened — you are clamping a bar, not torquing a wheel.
Check your work. Pull the chain down at the midpoint of the bar underside: the drive links must not come clear of the groove. Then rotate the chain around the bar by hand with a gloved hand — it should move smoothly with steady effort, not spin freely and not jerk or bind.
Oil the chain and re-check after a few cuts. A new chain will need adjusting again within the first hour, sometimes two or three times. That is normal bedding-in, not a fault.

Close-up detail of the material being worked in a pruning, trimming & hedges project, in soft early-morning light

Tool-free tensioners

Most modern battery saws and many corded ones use a combined system: an outer knob clamps the side cover, and an inner dial adjusts tension. The sequence is the same in principle.

Power down and let the chain cool. Release the chain brake.
Loosen the outer clamping knob one to two turns — do not remove it.
Turn the inner tensioning dial clockwise while lifting the bar nose.
Stop when the sag is gone and the drive links stay seated on a pull test.
Tighten the outer knob firmly by hand, nose still lifted.

The common failure with these systems is under-tightening the outer knob, which lets the bar creep forward under load and the chain go slack within a few cuts. Hand-tight means genuinely firm, not fingertip snug.

When tensioning does not fix it

Symptom	Likely cause	Fix
Adjuster at the end of its travel, chain still sags	Chain stretched past service life	Replace the chain; inspect the bar rails
Chain goes slack again after a few cuts	Bar nuts or knob not fully tightened	Retension and tighten properly with the nose lifted
Tensioning screw turns with no effect	Adjuster pin stripped or out of the bar hole	Remove the side cover, reseat the pin, replace if damaged
Chain tight one side, loose the other	Bent bar or unevenly worn rails	Dress or replace the bar — see why a saw cuts crooked
Chain binds after cooling	Tensioned while hot	Slacken slightly; always set tension cold
Chain jumps off the nose in a cut	Too loose, or a worn nose sprocket	Retension; inspect the bar tip sprocket for play

If the saw is running hot, smoking or the bar is discolored, the tension may be the cause rather than the symptom — see why is my chainsaw smoking. If the cut wanders off line, tension is rarely the culprit and sharpening or bar wear usually is: why does my chainsaw cut crooked.

Wide view of a person trimming a green hedge with shears, cut leaves falling, in bright midday sun

How often to check

Before every session, after the first few cuts with a new chain, and at every refuel or battery change. New chains stretch most in their first hour of use because the rivets and link plates are bedding in. All chains loosen when hot and tighten again as they cool, so the tension you set cold is not the tension you have mid-job — build the check into the natural pauses in the work rather than treating it as a separate chore. The target figures and the three verification tests are in how tight should a chainsaw chain be.

Safety

Stop the engine, remove the battery or unplug the saw before any adjustment. Wear cut-resistant gloves: chainsaw cutters open skin at a touch, and you will be rotating the chain by hand. Let a hot chain and bar cool before handling — both retain enough heat to burn.

Correct tension is a safety setting. A loose chain can derail and whip off the bar at full speed; a tight chain heats, robs power and can part. Both make the chain more likely to grab, and grabbing is what provokes kickback — the mechanism behind most serious chainsaw injuries, in which contact between the upper quadrant of the bar nose and any object drives the saw back and up toward the operator's head and shoulder faster than anyone can react. Keep the nose out of the cut, wrap your thumb fully under the front handle, and confirm the chain brake stops the chain before every session. OSHA lists a hard hat, safety glasses, hearing protection, heavy gloves, cut-resistant chaps and ankle-covering boots as standard chainsaw kit — see best chainsaw chaps. Never cut from a ladder or above shoulder height, and hand any leaning, split, hollow or power-line-adjacent tree to a certified arborist.

We never buy, test or physically handle the products we rank. Recommendations come from aggregated owner reviews, star ratings, review volume and expert consensus — see how we rank.

How to Tension a Chainsaw Chain