Startup runway & yield calculator
Last updated 2026-10-17. Rates snapshot 2026-10-16 from rates.json; each provider's figure has its own as-of date on its provider page.
Enter your cash balance and monthly burn. The calculator shows months of runway, what your idle cash would earn at each provider's published yield for that balance, and how many extra days of runway that interest buys.
10.0 months
| Provider | Yield at your balance | Interest / year | Interest / month | Extra runway |
|---|---|---|---|---|
| Ramp Ramp Investment Account | 4.63% headline (up to) | $46,300 | $3,858 | +7 days |
| Meow Meow Commercial Paper Account / T-Bills | 3.96% headline (up to) | $39,600 | $3,300 | +6 days |
| Arc Arc Treasury | 3.94% headline (up to) | $39,400 | $3,283 | +6 days |
| Brex Brex Business Account – Treasury | 3.62% Total treasury return | $36,200 | $3,017 | +5 days |
| Mercury Mercury Treasury | 3.60% Ultra-short bonds (MCRYX) | $36,000 | $3,000 | +5 days |
| Rho Rho Treasury | 3.58% 13-week T-Bills | $35,800 | $2,983 | +5 days |
| SVB (First Citizens) Startup Money Market Account | 3.56% headline (up to) | $35,600 | $2,967 | +5 days |
| Grasshopper Bank Innovator / Accelerator Savings | 3.25% headline (up to) | $32,500 | $2,708 | +5 days |
| Relay Relay Savings | 3.21% headline (up to) | $32,100 | $2,675 | +5 days |
| Bluevine Business Checking | 3.00% headline (up to) | $30,000 | $2,500 | +4 days |
| Found Found Plus / Pro | 2.50% headline (up to) | $25,000 | $2,083 | +4 days |
| Ramp Ramp Business Checking | 2.00% headline (up to) | $20,000 | $1,667 | +3 days |
How it works
- Yield at your balance: for providers that publish balance tiers (Brex, Mercury, Rho), the calculator uses the tier your balance falls in and the highest-yield option in that tier. For other providers it uses the headline "up to" yield, which may need a higher balance or a specific product. See each provider page.
- Interest: balance × yield, before taxes and before any fund expenses not already netted out by the provider.
- Runway: cash ÷ monthly burn. Extra runway assumes the yield stays constant, interest is earned monthly at yield ÷ 12 on the remaining balance, and burn stays flat. In practice yields move with the Fed and your balance changes tiers as it falls.
Before chasing yield, read where to keep startup cash: safety and liquidity come first. Compare all providers in the rates table.
FAQ
How much interest does $1M earn in a startup treasury account?
At the published rates in our 2026-10-16 snapshot, $1,000,000 earns about $46,300 a year at 4.63% (Ramp, headline rate). Among providers with published balance tiers, Brex pays 3.62% at $1M, about $36,200 a year. Yields are variable and not guaranteed.
How do you calculate startup runway?
Runway in months = cash balance ÷ monthly net burn. With yield, interest earned each month offsets part of the burn, so cash lasts a little longer; this calculator compounds interest monthly at the yield ÷ 12.
Does treasury yield meaningfully extend runway?
Usually by days or a few weeks, not months. With $1M in cash and $100K monthly burn (10 months of runway), a 3.62% yield adds roughly 5 days.
Are these yields guaranteed or FDIC insured?
No. Yields are variable and quoted as each provider advertises them on the as-of date shown. Money market funds, T-Bills and bond funds are securities, not FDIC-insured deposits, and can lose value.
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We keep your email private and use it only for this newsletter. Every issue will have an unsubscribe link.Not financial advice. IdleCash is an independent, informational comparison. We are not a bank, broker or adviser. The comparison table is always sorted purely by the data; sponsorship never changes rank. Yields are variable, quoted as each provider advertises them, and may have changed. Securities products are not FDIC-insured and can lose value. Verify on the provider's site before acting.