Per-second billing, same price, fairer math

TL;DR: Starting today, September 30, 2025, we bill per second at the exact same rate as before: $0.50 per minute, billed per second, which is $1/120 per second (about $0.008333). We round Half-Up to the nearest cent per call1 after the calculation, we never round your time. Two-week notice: starting October 14, 2025, calls under 10 seconds will be billed per second as well. Included credit dollars are unchanged, only the unit changes to seconds.

Why we changed it

Per-minute rounding punished short calls. Per-second billing is fair and predictable. Your total price is the same as before, the rounding is just less silly.

What exactly is changing

  • Effective date: As of September 30, 2025, any call lasting 10 seconds or longer is billed per second.

  • Rate: Still $0.50 per minute, now metered per second. That is $1/120 per second.

  • Rounding: We compute elapsed_seconds × $1/120, then round Half-Up to the nearest cent per call. We never round the time itself.

  • Credits are now in seconds: Same dollars, different unit so you do not see fractional credits.

    • Free: $10 monthly credit becomes 1205 seconds (about 20 minutes).2
    • Plus: $50 monthly credit becomes 6024 seconds (just over 100 minutes). This plan is a steal since it only costs $20/month.
    • Pro: still unlimited usage through Zoo Design Studio and Text-to-CAD generator.
    • Everything else: unchanged in dollars, unit is seconds.

  • Short calls policy: Historically, sub-10-second calls were not billed. Starting October 14, 2025, we will bill them per second with the same rate and rounding.

How the math works (so you can check us)

  • Rate: $0.50/min = 50 cents per 60 seconds = 5/6 cent per second.
  • Half-Up to cents: values ending in exactly half a cent round up.

If you like integer math, you can think in cents. For a call of s seconds:

cents = floor((5*s + 3) / 6)   # Half-Up for 5/6 cent per second

Examples

  • 32 s → ((5*32)+3)/6 = 163/6 = 27 cents → $0.27
  • 60 s → ((5*60)+3)/6 = 303/6 = 50 cents → $0.50
  • 95 s → ((5*95)+3)/6 = 478/6 = 79 cents → $0.79

Small calls behave as you expect:

  • 1 s → 0.833… cent → $0.01
  • 2 s → 1.666… cents → $0.02
  • 5 s → 4.166… cents → $0.04

Note: because we round each call to cents, many tiny calls can sum to a hair more than one long call with the same total seconds. This is standard for usage billing. If that ever meaningfully impacts you, tell us.

What you need to do

Most users do nothing. If you are not on a subscription plan, your invoice lines simply show per-second items with cent rounding.

FAQ

Will my bill go up? No, the rate is unchanged. Per-second metering just removes minute-rounding artifacts, so short calls are billed more precisely.

Why seconds instead of fractional credits? Seconds are concrete and easy to reason about. Fractional credits would just mirror the dollar amount, so why juggle two numbers that mean the same thing? Also nicer for client code than 13.37 credits.

When do short calls start getting billed? Per-second billing for calls 10 seconds and up started today, September 30, 2025. Starting October 14, 2025, sub-10-second calls are billed per second with the same rounding.

Fair pricing, cleaner counters, less grumpiness. If anything looks off, ping us and we will fix it.

Footnotes

  1. “Half-Up to the nearest cent” means anything under half a cent stays at the lower cent, and values landing exactly on the half round up to the next cent. ↩

  2. We surface price-per-second math off a single rounded constant set to $0.0083 so the numbers stay readable. That truncation slightly overstates the seconds you see in your favor (for example 1205 seconds ≈ $10 and 6024 seconds ≈ $50) compared with the exact $1/120 math. Invoices run off that same constant and Half-Up rounding, so the tiny bonus sticks with you. ↩

Jessie Frazelle

Jessie Frazelle