Fight Your Zombie Upgrade & Prestige Calculator Guide
Step formulas, ROI tables, and prestige timing math — no guesswork on zombie, tank, and Void spends.
Guides explain what to buy in Fight Your Zombie; this upgrade calculator guide teaches when a purchase pays for itself and when prestige beats one more hour of grinding. Simple Bricks Zombies hides exact constants behind UI, but incremental players still win with observable metrics: coins per minute (CPM), brains per hour (BPH), and Void multiplier gain (VMG). Use the formulas and tables below with a phone calculator during sessions — no custom JS required.
Pair this page with Upgrade Order, Prestige and Void, and Offline Planner. Patch changes land on Changelog — retest constants after Saturday updates.
Core symbols
| Symbol | Meaning |
|---|---|
| CPM | Coins per minute from plot fights after feeding |
| BPH | Brains per hour from all tanks (online + offline average) |
| UC | Upgrade cost in coins |
| ΔCPM | CPM after upgrade minus CPM before |
| VMG | Void multiplier gain from next prestige node |
| T | Time in minutes |
Measure CPM over three full fight cycles after feeding Shiny or Rainbow when possible — see Shiny Rainbow Brains.
Formula 1: upgrade payback time
Payback (minutes) ≈ UC ÷ ΔCPM
Example: Zombie upgrade costs 50,000 coins and raises CPM from 800 to 1,000.
- ΔCPM = 200
- Payback = 50,000 ÷ 200 = 250 minutes (~4.2 hours active fight time)
Buy if payback is shorter than your planned play window before the next prestige or 2x luck event. Skip if payback exceeds two sessions and a prestige node offers VMG above 15%.
Formula 2: brain starvation check
If fights wait on feeds:
Effective CPM = CPM × (feed uptime %)
Feed uptime = minutes with fed zombie ÷ total session minutes.
When uptime < 70%, prioritize brain tanks or machines before zombie upgrades — math on paper cannot fix empty feeds. Use Controls feed flow until uptime recovers.
Formula 3: tank ROI vs zombie ROI
Compare two paybacks:
- Tank upgrade that raises BPH and indirectly CPM via better feeds
- Zombie upgrade with direct ΔCPM
Whichever has lower payback minutes wins the next coin slot — ties go to tanks if offline growth is part of your routine.
Formula 4: prestige break-even
Prestige when:
VMG × projected next-run CPM > current-layer ΔCPM from one hour grind
Practical shortcut:
- Note current CPM and next Void node VMG from prestige UI.
- Estimate post-prestige CPM at same upgrade depth (historically 1.4×–2× first hour if you follow upgrade order).
- If VMG × projected CPM gain ≥ 120% of one hour current CPM, prestige is reasonable.
Cross-check Prestige and Void red/green lists. With seven or more prestige badge levels visible, reruns compress faster — log your personal multiplier after each reset.
Reference table: spend priority by stage
| Stage | First buy | Second buy | Third buy | Tool check |
|---|---|---|---|---|
| Hour 1 | Zombie tier 1–3 | Tank slots | — | Feed uptime |
| Day 1 | Zombie multipliers | Tank fill rate | Starter machine | Payback < 3h |
| Mid | S-tier farm | Synthesizer / Melter | Weapons | BPH vs CPM |
| Pre-Void | Tank capacity | VMG threshold | Hoard lucky keys | Prestige formula |
| Void rerun | Zombie breakpoint | S-tier machines | Passes optional | Changelog |
Full narrative: Upgrade Priority tier list.
Table: game pass break-even hours
Approximate hours saved — verify live prices on Game Passes:
| Pass | Cost | Assumed benefit | Break-even if… |
|---|---|---|---|
| OP Auto Clicker | 149 R$ | +25% effective fight clicks | You fight 2+ hrs/day |
| VIP | 599 R$ | +10% coins if perk live | Tooltip shows real % boost |
| Super Sword | 999 R$ | +30% fight DPS | Zombie stats maxed; uptime >85% |
| Super Machine | 999 R$ | +20% machine BPH | S-tier farm already placed |
Passes multiply working builds — they do not fix starvation.
Table: 2x luck upgrade shift
During Events 2x Luck, temporarily prioritize:
| Normal priority | Luck-week priority |
|---|---|
| Weapon tier | Tank capacity |
| B-tier machine | Proc-rate farms |
| Cosmetic | Lucky block openings |
Revert Monday per Events guide.
Step worksheet (copy to notes app)
- Feed Shiny/Rainbow → run 3 fights → record CPM₁
- Buy candidate upgrade → run 3 fights → record CPM₂
- ΔCPM = CPM₂ − CPM₁
- Payback = UC ÷ ΔCPM
- If prestige available: record VMG, compare Formula 4
- If payback loses to prestige, reset; else buy next zombie/tank tier
Repeat after each Saturday patch.
Machine-specific notes
Brain Melter and synthesizers need Normal overflow to justify cost — see Machines. Calculate Melter payback as:
Melter payback ≈ Melter UC ÷ (ΔRainbow value per hour × feed conversion rate)
If you cannot estimate Rainbow value, delay Melter until Shiny Rainbow procs stabilize.
What this guide is not
- Not a script or executor — Scripts Safety
- Not code redemption — Codes Hub has none
- Not a live auto-calculator page yet — run math manually or extend later
Accuracy disclaimer
Simple Bricks Zombies rebalances silently. If payback drift exceeds 15% vs your logs, report on official Discord and reread Changelog.
Related pages
- Upgrade Order — narrative priority
- Prestige and Void — reset timing
- Offline Planner — BPH estimation
- Tools Hub — tool index
- Brain Tanks — supply side math
Incremental games are spreadsheets with animations. Run the payback formula once per major purchase and prestige with evidence — not impatience.
Frequently Asked Questions
Quick answers to the most common questions.
What is the upgrade payback formula?
Payback minutes ≈ upgrade cost divided by coins-per-minute gain (ΔCPM). Buy when payback fits your session plan.
When should I prestige using math?
When Void multiplier gain times projected next-run CPM beats roughly one hour of current-layer grinding.
Does this page run calculations automatically?
No. It teaches formulas and tables you apply with a basic calculator during play.
What metric should I track first?
Coins per minute after feeding, measured over three fight cycles for stability.
How do 2x luck events change the calculator?
Temporarily prioritize tank capacity and proc upgrades over weapons. Revert after the event.