Automatic Watch Running Fast? 6 Causes and How to Fix Each One
Your automatic watch is gaining time, maybe a few seconds a day or several minutes. Before you send it for service, it helps to know what is normal and what is not. In most cases the cause is simple, and in one very common case you can fix it yourself in seconds.
First: how accurate should your watch be?
Mechanical watches are never as accurate as quartz. Each manufacturer publishes an accuracy tolerance per day:
| Movement | Official tolerance (per day) |
|---|---|
| Seiko NH35 / NH36, 4R35 / 4R36 | -20 to +40 seconds |
| Seiko 7S26 | -20 to +40 seconds |
| Seiko 6R35 (Prospex, Presage) | -15 to +25 seconds |
| Miyota 8215 | -20 to +40 seconds |
| Miyota 9015 | -10 to +30 seconds |
| COSC-certified chronometer | -4 to +6 seconds (tested uncased, in set conditions) |
So if your Seiko 5 gains 15 seconds a day, it is working exactly as designed. A watch gaining more than its tolerance, or suddenly gaining minutes a day, has a real cause worth finding.
How to measure the error properly
- Fully wind the watch (see our winding guide).
- Set it exactly to a reference such as time.gov or time.is. Hacking movements make this easy.
- Wear it normally for 24 hours, then compare. Repeat for 2–3 days and average the result.
A single day is misleading, because the rate changes with how you wear the watch and how it rests at night.
Cause 1: Magnetization (the most common cause of big gains)
If your watch suddenly gains minutes per day, it is very likely magnetized. Phone speakers, laptop lids, tablet covers, magnetic bag clasps and speakers can magnetize the hairspring. Its coils then stick together, the effective length shortens, and the watch runs very fast.
How to check: place a basic compass on a table, then slowly move the watch near it. If the needle twitches as the watch passes, it is magnetized. Many phone compass apps can also give a rough reading.
How to fix: a watch demagnetizer (a small, inexpensive blue box sold online) removes magnetism in seconds. Place the watch on it, press the button, and slowly lift the watch away while holding the button. Any watch shop can also do it, usually for free or a small fee.
Prevention: keep the watch a few inches away from laptops, tablet covers, speakers and magnetic phone mounts.
Cause 2: Resting position overnight
Mechanical watches run at slightly different rates in different positions (dial up, crown down, crown up, and so on). You can use this to your advantage:
- Note your daily gain, then try different resting positions at night for a few days each.
- If the watch gains during the day, find the position where it loses slightly overnight. That cancels out part of the daytime gain.
Many owners get a 30-second-per-day watch to within a few seconds per day this way, without opening anything.
Cause 3: Low or very full power reserve
Rate changes with how wound the mainspring is. Some movements run slightly fast when fully wound and slower as they run down, or the reverse. If you only wear the watch a few hours a day, it may be running at a low wind state. Give it 20–30 turns each morning and measure again.
Cause 4: Shock
A drop or a hard knock (golf, tennis, hammering) can shift the hairspring or regulator slightly. If the gain started right after an impact, this is a likely cause. It needs a watchmaker to inspect and regulate.
Cause 5: Temperature
Extreme heat or cold changes the elasticity of the hairspring. Modern alloys reduce this, but a watch left in a hot car or worn in very cold weather may run differently. This is temporary.
Cause 6: Old lubrication or needed service
As oils age (typically after 5–10 years, depending on the movement), friction changes and accuracy drifts. Erratic timekeeping, reduced power reserve or a rotor that sounds noisy are signs a service is due.
Can you regulate it yourself?
Technically, yes. Most movements have a regulator arm under the balance that adjusts the rate. But it means opening the case, which can let in dust and moisture and can affect water resistance. Unless you have the right tools and some experience, a watchmaker can regulate an NH35 or Miyota in a few minutes, often at low cost.
Quick troubleshooting table
| Symptom | Most likely cause | What to do |
|---|---|---|
| Gains 5–40 s/day steadily | Normal for the movement | Try a different overnight resting position |
| Suddenly gains minutes per day | Magnetism | Demagnetize |
| Gain started after a knock | Shock | Watchmaker inspection |
| Gains on some days, loses on others | Wearing pattern / wind level | Wind daily, measure over 3 days |
| Erratic, short power reserve, noisy rotor | Service due | Full service |
FAQ
Is it normal for an automatic watch to gain time?
Yes. Most affordable automatic movements are specified within roughly -20 to +40 seconds per day, and many manufacturers set them to run slightly fast on purpose, since running slightly early is less of a problem than running late.
Can my phone magnetize my watch?
It can, especially phone speakers and magnetic accessories like MagSafe-style wallets and mounts. Short contact is usually fine, but resting the watch on them for long periods is a common cause.
How much does demagnetizing cost?
Many watch shops do it for free while you wait. A home demagnetizer usually costs less than a takeaway lunch.
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