Star Force cost is tapping. Replacement cost is expected booms × your spare-item price; leave it 0 to price tapping alone.
Average is the exact expected cost. Median is the 50th percentile: half of runs finish under it.
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Star Force calculator
Expected cost, booms, and per-star rates for any Star Force target.
Item
Options
Cost summary
31.30B
0
7.25
Total 31.30B · 17★ → 22★
Protection plans
| Star | Protect | Success | Boom | Cost |
|---|---|---|---|---|
| 17→18★ | — | 15.8% | 6.7% | 1.48B |
| 18→19★ | — | 15.8% | 6.7% | 3.33B |
| 19→20★ | — | 15.8% | 8.4% | 7.06B |
| 20→21★ | — | 31.5% | 10.3% | 4.55B |
| 21→22★ | — | 15.8% | 12.6% | 14.88B |
Starforce
Whisper of the Source
1718
Success Rate
Success15.75%
Failure (Keep)77.51%
Failure (Destroy)6.74%
Material Cost
130,688,600 Mesos
Attempts
0
Destroyed
0
Mesos Spent
0
About this tool & FAQ
This Star Force calculator prices an ordinary GMS Star Force upgrade from raw inputs: item level plus your current and target stars. It uses the same per-star success and destroy rates as the Upgrade Tracker planner, so the expected meso cost, expected boom count, and per-star breakdown match what the full planner would recommend.
It supports regular-server tapping with Safeguard, MVP discounts, and cost or boom-reduction events, and it reports both the exact average cost and a simulated median so streaky outcomes are visible.
Frequently asked questions
How is the expected Star Force cost calculated?
From the official per-star success, fail, and destroy rates: the calculator computes the expected attempts and booms to walk your star range, prices each attempt at that star’s meso cost for your item level, and adds expected booms times your spare-item price if you set one.
What happened to Star Catching?
The v.271 update removed the minigame and made its bonus permanent: every attempt’s success rate is 1.05 times the base rate (a 5% relative increase). The calculator applies it to every tap, so there is nothing to switch on.
When is Safeguard available and what does it do?
Safeguard can be used on the 15→16, 16→17, and 17→18 star attempts. It removes the destroy chance on those attempts and triples their meso cost. The "Optimal" setting picks per star whether paying for Safeguard is cheaper than eating the boom risk.
Which events does the calculator support?
The 30% off cost event, the −30% boom chance event, and Shining Star Force (both at once), plus MVP Silver, Gold, and Diamond cost discounts.
Does this cover Superior, Zero, and Reboot items?
No. This calculator prices ordinary Star Force on regular servers. Superior items, Zero weapons, and Reboot use different rate and cost tables, which the in-app planner handles.
What is the difference between the average and median cost?
Average is the exact expected cost from the rate tables. Median is the 50th percentile of a simulation of the same rates: half of runs finish under it. Boom streaks drag the average above the median, so the gap shows how spiky your target range is.