Bolt throw is the distance a deadbolt's bolt slides out of the door edge when you turn the key or thumb turn. With the door open you can watch it move out until it stops. That extension decides how much of the bolt can sit inside the frame once the door is closed. It only counts when the bolt lines up with the strike plate and the frame behind it is solid.
The bolt is only half of a pair
A deadbolt's bolt is the solid metal piece that slides out of the door edge and into the frame. The spring latch is the angled piece that clicks shut on its own. The bolt is different because it moves only when you turn the key or thumb turn. Throw is the part of that bolt that crosses from the door into the frame.
Two things on the frame side receive the bolt. The strike plate is the metal plate screwed to the jamb, with an opening for the bolt. Behind that opening is a hole bored into the frame, often called the bolt pocket. The bolt can travel only as far as the pocket allows, so a shallow or blocked hole stops it short even when the lock is fine.
How far a deadbolt should stick out is not a number to measure at home. The useful check is whether the bolt reaches its full stop and goes all the way into the pocket when the door is closed. A bolt that stops partway leaves less of itself in the frame than the lock was built to put there.
Does a longer bolt throw make a door more secure?
A longer throw puts more bolt inside the frame, which gives the door more to hold against. That is all throw does. Throw does not decide by itself how well the door stays shut.
Picture how a locked door is loaded. A push on the door travels through the bolt into the strike plate, then into the frame. The weakest point in that chain sets the limit. A strike held by short screws in thin trim, a jamb split around the pocket, or a frame that flexes away from the door can give way while the bolt stays straight.
Alignment matters the same way. A bolt that catches the edge of the strike opening and only partly enters has less engagement than its throw suggests. A generous throw on a door that sits crooked can hold less than a modest throw on a door that closes square.
A bolt that extends well with the door open shows what the lock can do. Only the closed door shows what the frame lets it do.
What you can check at your own door
- With the door open, turn the key or thumb turn all the way. The bolt should slide out smoothly and stop firmly. Sticking, grinding, or stopping short points to something inside the lock.
- Close and lock the door. The turn should feel about the same as it did with the door open. If you have to lift, push, or pull the door to finish the turn, the bolt is rubbing the strike.
- With the door locked, push and pull gently near the lock. A clear rattle or knock suggests a shifted strike, an oversized opening, or loose strike screws.
- Look at the strike plate. Scrape marks above or below the opening show where the bolt has been hitting.
Each result points somewhere different. Trouble with the door open means wear or damage in the lock. A bolt that works open but fights closed means alignment, usually because the door has sagged, the hinges have loosened, or the strike sits slightly off. Rattle points to the strike and the frame behind it.
A deadbolt that feels like it barely catches usually has an alignment problem. The bolt meets the strike at an angle or lands at the edge of the opening, so only part of its throw reaches the pocket.
Have the hardware looked at when the bolt locks only with the door held a certain way, when the strike or frame is cracked or loose, or when the lock no longer throws fully. Nostrand Locksmith handles door hardware repair, lock changes and rekeying, and high-security locks in Bedford-Stuyvesant, Crown Heights, Clinton Hill, and the rest of Brooklyn. You can call (516) 644-8976 to describe what you are seeing.
Frequently asked questions
Can a deadbolt be locked with the door open, and is that bad for it?
A deadbolt can be thrown with the door open, and that does no harm to the lock. It is the easiest way to see the full throw. The trouble starts if the door is swung shut with the bolt still out. The bolt hits the frame edge, and repeated hits can bend the bolt, chip the jamb, or loosen the lock in the door.
Why does my deadbolt only work if I lift or push the door?
A deadbolt that locks only when you lift or push the door is out of line with its strike plate. Lifting raises the bolt to an opening that sits too high. Pushing closes a gap so the bolt can reach the pocket. A sagging door, loose hinge screws, or a shifted strike are common causes, and forcing the turn wears the lock.
Does a heavier-feeling bolt mean the lock is better?
A heavier feel does not make a deadbolt better. How hard the bolt turns depends on the internal mechanism and on any friction against the strike plate. It does not tell you how well the door holds. A turn that is stiff only with the door closed usually means the bolt is dragging on the strike. Look for a smooth turn that stops firmly at full throw.
Can a deadbolt be adjusted if it isn't lining up with the frame?
A deadbolt that misses its strike can often be brought back into line without replacing the lock. Depending on the cause, that may mean correcting how the door hangs on its hinges, moving the strike plate, or deepening the bolt pocket. If the frame around the strike is split, or the lock itself no longer throws fully, repairing or replacing that hardware is the likelier route.