The math behind
the toll.

Every number in CurbToll traces back to minutes you actually focused — no abstract points, no fuzzy XP. Here's the whole system, formula by formula. Nothing hidden.

Net Focus Score Time Credits Diamonds Spend & convert Decay A worked day
01

Net Focus Score

One number summarises a day. It's what your squad sees and what your streak rides on — and it carries no multipliers, so it stays fair across free, premium and IAP users alike.

NFS = (Focus min × 2) − Doomscroll min
Raw minutes only · negative NFS tints the dashboard
Doomscroll rates
Every distracted minute deducts, no matter how you got in. Spending credits or converting diamonds: −1 NFS/min. Soft override: −2 NFS/min. Only "hold the line" protects the score.
Worked example
98 m focus × 2 = 196
− 12 m doomscroll = +184
A strong day: nearly two hours focused, twelve minutes lost.
02

Time Credits

The spendable currency — the one you trade to cross the toll. Credits are where every bonus lives: time of day, streak and chain all stack additively onto a flat base rate.

Credits = Base × (1 + Time + Streak + Chain)
Base = 0.2 credits / min  ·  5 credits per 25-min block
BonusConditionFreePremium
Early bird6–9 am+0.2×+0.2×
After Dark6–9 pm+0.5×+0.5×
Weekend / holidaySat–Sun + bank hol.+1.0×+1.5×
Streak ≥ 7 daysstreak held+0.2×+0.2×
Chain · session 2restart in window+0.3×+0.3×
Chain · session 3+unbroken chain+0.5×+0.5×
Maximum stackbest-case day3.2×3.7×
Bonuses are additive, not multiplicative, and the multiplier locks at session start — an 8:45 am session keeps its early-bird bonus even if it runs past 9. Credits round down to whole numbers.
Worked · 45-min weekend sessionChain 2 · streak 12d
Base · 45 m × 0.29
+ Weekend+1.0×
+ Streak ≥ 7 days+0.2×
+ Chain · session 2+0.3×
Credits earned · 2.5×9 × 2.5 = 22
03

Focus Diamonds

The cosmetic currency — flat, predictable, and deliberately boring. Diamonds take no multipliers, ever, and they never decay. They're for the shop and the emergency conversion, nothing that touches the leaderboard.

♦ = floor( Focus min ÷ 2 )
Always whole numbers · same rate whether earned or bought
25 min
12 ♦
50 min
25 ♦
90 min
45 ♦
New account
+100 ♦
Signup bonus, plus 20 starting credits.
04

Spending & conversion

Credits buy scroll time. Diamonds can be converted to credits when you're tapped out — but it's priced as a genuine last resort. Protected days (weekends & bank holidays) halve both rates.

Credit spend
1 credit = 1 minute of shielded-app time on a normal day. On protected days, 0.5 credit / min — apps cost half.
Diamond → credit
50 ♦ = 1 credit on a normal day; 25 ♦ = 1 credit on protected days. At ½♦ per focus-minute, 50♦ is ~100 focus-minutes traded for one scroll minute.
Why so punishing? The conversion is the safety valve, not a shortcut. Painful-by-design keeps diamonds from quietly becoming a way to buy your way past focus.
05

Credit decay

Credits are soft currency — go idle and they fade, so a balance can't sit hoarded forever. But it's gentle: a streak-scaled grace period, then a flat loss, floored at zero, with a warning long before.

Grace = clamp( 1 + floor(streak ÷ 7), 1, 7 ) idle days
Then −10 credits / idle day · floor 0 · one session freezes the day
StreakGrace days
0–6 days1
7–13 days2
14–20 days3
21–27 days4
28–34 days5
35–41 days6
42+ days7 (cap)
Idle projection · 120 credits · 1-day grace
A flat −10 a day after grace — a full week idle costs about 60 credits, not the whole balance. You're warned the morning the drain starts, and the dashboard flags it as critical while you still have two days' worth of credits left.
06

A worked day

One Saturday, end to end — how a couple of sessions and one slip resolve into the three numbers.

Sat · 23 May · free tierWeekend · streak 12d
Net Focus Score
Focus · 98 m × 2+196
Doomscroll · 12 m × 1−12
NFS today+184
Time Credits (carry the 2.5× weekend stack)
Earned · three sessions+48
Spent · 12 m × ½ (weekend)−6
Credit balance42
Diamonds (flat · floor(min ÷ 2))
Earned today+49 ♦

Numbers you can trust.

Every formula above runs the same for everyone. No pay-to-win, no hidden multipliers.

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