What this calculator does
The player moving around a corner sees the defender before the defender sees them. This is not a bug and it is not lag in the usual sense. It is the unavoidable consequence of the defender's screen showing a version of the world that is a few dozen milliseconds old.
The window is small and it is decisive. At typical settings it is around 50 milliseconds, which is between seven and eight frames at 144 fps and about 29 centimetres of movement. That is enough for the peeker to be aiming while the defender is still looking at an empty corner.
The formula
Four delays add up. The peeker's movement takes half their round-trip ping to reach the server. The server holds it for up to one tick, half a tick on average. Sending it on takes half the defender's ping. Finally the defender's client deliberately buffers incoming data by the interpolation delay so that movement renders smoothly. The sum is peeker ping ÷ 2 + defender ping ÷ 2 + half a tick + interpolation. This is a model with each term as an input rather than a measurement of any one game.
| Term | Meaning |
|---|---|
| Round-trip ping | The full there-and-back time. Half of it is the one-way delay, which is what matters here. |
| Tick rate | How often the server updates. A 64 Hz server has 15.6 ms between ticks, so half a tick is 7.8. |
| Interpolation buffer | A deliberate delay on the client so movement between server updates renders smoothly. Often one or two ticks. |
| Advantage window | How long the peeker is visible to themselves before they are visible to the defender. |
The inputs explained
| Field | What to enter |
|---|---|
| Peeker ping (round trip) (ms) | The peeker's round-trip ping in milliseconds, as the scoreboard reports it. |
| Defender ping (round trip) (ms) | The defender's round-trip ping. Both matter, which is why a low ping does not protect you from a high-ping opponent. |
| Server tick rate (Hz) | Server updates per second. Competitive shooters run between 20 and 128. |
| Interpolation buffer (ms) | The client interpolation delay. If you do not know it, one or two tick intervals is a reasonable guess. |
| Defender frame rate (fps) | The defender's frame rate, used only to express the window in frames. |
| Peeker movement speed (m/s) | How fast the peeker moves, used to turn the window into distance. |
When to use it
Understanding why holding an angle feels unfair
It is unfair, in a precise and measurable sense. The defender is reacting to information that is already stale by the full window, and no amount of reaction speed recovers time that has not arrived yet.
Seeing what a higher tick rate actually buys
Going from 64 Hz to 128 Hz halves the tick contribution from 7.8 ms to 3.9. That is a real improvement and a small one against a 30 ms ping, which is why tick rate debates generate more heat than milliseconds.
Working out whether to hold or to peek
If the window is large, the player taking the duel first has the edge, and holding a static angle is the weaker play. Comparing the window against your own reaction time, usually 150 to 250 ms, puts it in proportion.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much does ping change the advantage?
Only the peeker's ping changes.
| Peeker ping | Advantage window | Frames behind | Metres cleared first |
|---|---|---|---|
| 0 ms | 37.8 ms | 5.4 | 0.21 m |
| 20 ms | 47.8 ms | 6.9 | 0.26 m |
| 40 ms | 57.8 ms | 8.3 | 0.32 m |
| 60 ms | 67.8 ms | 9.8 | 0.37 m |
| 100 ms | 87.8 ms | 12.6 | 0.48 m |
Is a higher tick rate worth it?
Only the server tick rate changes.
| Tick rate | Advantage window | Tick interval |
|---|---|---|
| 20 Hz | 70.0 ms | 50.00 ms |
| 30 Hz | 61.7 ms | 33.33 ms |
| 64 Hz | 52.8 ms | 15.63 ms |
| 128 Hz | 48.9 ms | 7.81 ms |
| 256 Hz | 47.0 ms | 3.91 ms |
Questions
Is peeker’s advantage the same as lag compensation?
No, though they interact. Lag compensation rewinds the server to decide whether a shot hit. Peeker's advantage is about who sees whom first, and it exists even when every shot registers correctly.
Can a game remove it?
Not entirely. Some of the window is the speed of light through cable, and the rest is a deliberate smoothing buffer that removes stutter. Games can shrink it with a higher tick rate and a smaller buffer, at the cost of bandwidth and smoothness.
Does my frame rate affect it?
Only slightly. Frame rate adds up to one frame of its own delay, which is 7 ms at 144 fps against a window of around 50. The frame time calculator puts that in the same units so you can compare.
Why does the defender’s ping matter if they are standing still?
Because the peeker's movement has to travel to the defender's machine. That leg takes half the defender's round trip regardless of whether the defender is moving.
Is this model exact for my game?
No. It is an additive model of four known delays, and real engines add their own buffering and prediction. Use it to compare settings against each other rather than as a measurement.
The other half of the latency chain is on FPS to frame time, and the piece on frame time explains why milliseconds are the only unit worth adding up. For aim consistency there is cm per 360.