Speed (SPD) in Honkai: Star Rail — Key Breakpoints Explained
Turn order in Star Rail is decided by Action Value (AV) = 10000 / SPD — the higher your SPD, the lower your AV, so you act sooner and more often. The community tracks three main-DPS breakpoints: 134 SPD (2 actions in Memory of Chaos's first 150-AV cycle), 142.9 SPD (5 actions across the first 3 cycles), and 160 SPD (4 actions in just the first 2 cycles). SPD% buffs always add together and get applied once to your base SPD — they never multiply on top of each other, so stacking more of them gives linear, not exponential, gains.
What AV Is and Why SPD Is the King Stat
Star Rail doesn't work like most turn-based games where turns just go in a fixed order. Every unit — allies and enemies alike — has its own countdown called Action Value (AV), calculated as AV = 10000 / SPD. Whoever hits the lowest AV acts next, then that unit's AV resets using the exact same formula and starts counting down again.
Think of it like a 10,000-meter race track. Higher SPD means you cover that distance faster, so you reach the finish line (AV hits 0) sooner — and over a long enough fight, you can effectively lap the slower units and squeeze in extra turns they never get.
That's why veteran players call SPD the "king stat." A single SPD buff or debuff doesn't just move you up the queue once — it can win you an entire bonus action while the enemy is still crawling toward its turn. Energy generation from extra Ultimates, early Toughness breaks, and delaying a boss's turn (Advance Forward / Action Delay effects) all ride on this same AV math.
The Real SPD Formula: How % Buffs Actually Stack
The SPD number on your final stat sheet comes from: SPD = Base SPD × (1 + total SPD%) + Flat SPD. Base SPD here includes the character's innate speed plus any fixed % from Traces or passive skills. The "total SPD%" part is everything that adds together — teammate skill/Ultimate speed-ups, Light Cone effects, and other percentage sources combined.
The one thing worth remembering: SPD% buffs always apply to your Base SPD, never to the current on-screen SPD number above your character's head. So three separate +10% SPD buffs add up to +30% on the base value — they don't multiply like 1.1 × 1.1 × 1.1. Stacking more SPD% sources gives you linear gains, not exponential ones.
Flat SPD (like a fixed amount from certain relics or kit effects that add a raw number) gets tacked on last, after all the percentage math is done — no multiplier involved there.
The Community Speed Breakpoints in Memory of Chaos
Memory of Chaos runs on an uneven AV structure: the first cycle is 150 AV long, but every cycle after that is only 100 AV. That asymmetry is exactly what creates these sharp "breakpoints" — a small amount of extra SPD can be the difference between squeezing in one more action and not.
Three DPS breakpoints get referenced constantly: 134 SPD is the lowest threshold that gets you 2 actions inside that first 150-AV cycle — it's the go-to sweet spot for most main DPS because you're not giving up much ATK/Crit to hit it. 142.9 SPD steps that up to 5 total actions across the first 3 cycles. And 160 SPD — territory for builds with room to spare — nets you 4 actions in just the first 2 cycles, nearly doubling your action frequency compared to a slower build.
There's also 120 SPD, which matters for more than turn count (it's good for roughly 3 actions across the first 2 cycles) — it's also the threshold that unlocks the bonus effect on certain Planar Ornaments like Space Sealing Station, Fleet of the Ageless, and Sprightly Vonwacq. Fall short of 120 and that bonus half of the effect simply doesn't trigger.
SPD Boots or ATK% Boots — Picking the Right One for the Role
Your Feet relic always forces a choice between +SPD or +HP%/DEF%/ATK%. General rule: main DPS — especially ones that live off extra actions and fast Energy regen — should lean toward SPD boots to reach 134 (or higher if the rest of the build allows), because one bonus action usually outweighs the damage you're giving up from ATK%. But if your build already sits at a good breakpoint from your Light Cone, Traces, or teammate buffs, switching to ATK% boots to hit harder per hit makes more sense.
Support and Sustain units (shielders/healers) play a totally different game: their job isn't maximizing their own damage, it's acting BEFORE the DPS to land buffs, debuffs, and heals in time — or to interrupt a dangerous boss attack. That's why supports usually get pushed well above the DPS's SPD (many comps deliberately keep support SPD a comfortable margin ahead), and SPD boots are basically the default pick for this role unless their Light Cone specifically wants %HP or %DEF on the feet slot.
Practical tip: don't obsess over the SPD number on your home-screen stat sheet — calculate your in-combat SPD instead, meaning your base SPD plus whatever team-wide SPD% buffs your comp regularly brings. A lot of teams need less base SPD than you'd think because external buffs carry them over the breakpoint anyway.
FAQ
Do SPD% buffs from different sources stack multiplicatively?
No. Every SPD% source (Light Cone, Traces, teammate buffs, etc.) adds together first, then gets applied once to your Base SPD: SPD = Base SPD × (1 + total %) + Flat SPD. Three separate +10% buffs give you +30%, not three separate 1.1x multiplications.
What if my relics can't hit the 134 breakpoint?
That's completely fine — breakpoints are optimization targets, not requirements to clear content. Falling a few SPD short of 134 just means one less bonus action compared to an optimized build; you can still clear Memory of Chaos or Pure Fiction just fine. Prioritize ATK/Crit and your 4-piece set bonus first, and let SPD fall wherever your remaining substats land.
Why do so many people care about 120 SPD specifically?
120 SPD is the threshold where certain Planar Ornaments (Space Sealing Station, Fleet of the Ageless, Sprightly Vonwacq, etc.) unlock the bonus half of their 2-piece set effect — below that, you only get the base part of the buff. On top of that, 120 SPD is already enough to squeeze out an extra action within Memory of Chaos's first two cycles.